Graph-based vertical federated learning (GVFL) enables multiple parties to collaboratively train and infer over aligned nodes, where each party contributes its own local embedding derived from different attributes and adjacency relations. Adversarial inputs injected by an attacker can skew the joint prediction toward its desired outcomes while diminishing the influence of benign parties and undermining contribution. However, most attacks typically have pre-set assumptions, such as access to the server architecture, model queries, or in-domain auxiliary graphs. In this paper, we propose SGAC, an attack framework that enables domination of joint inference without relying on above assumptions. SGAC learns label-indicative embeddings and class-transferable probabilities to generate a surrogate that closely mimics the server-side classification behavior by exploiting auxiliary graphs from non-training domains. SGAC then leverages saliency over node attributes and edges on the auxiliary graphs to construct a diverse set of shadow inputs resembling highly influential test instances. With the surrogate fidelity and input diversity, SGAC crafts transferable contribution-monopoly adversarial inputs that hijack GVFL incentives. Extensive experiments across diverse model architectures validate SGAC's effectiveness.

While retrieval-augmented generation systems partially address the hallucination issues in large language models, it also introduces new vulnerabilities to knowledge corruption attacks. Adversaries exploit these vulnerabilities by poisoning documents provided by RAG system to manipulate LLM outputs. To counter this threat, we propose SecureCollaRAG, a Byzantine-tolerant collaborative RAG framework leveraging Multi-source Knowledge Validation Mechanism. Our approach enables agent system to securely verify document provenance through dynamic GNN-based credibility scoring, effectively preventing stealthy knowledge corruption attacks while preserving essential domain knowledge integrity. Through extensive evaluations and formal analysis, we demonstrate that SecureCollaRAG maintains robustness against attackers under non-IID data distributions.

The proliferation of AI-Generated Content (AIGC) within cloud-edge IoT ecosystems necessitates robust provenance mechanisms to ensure copyright protection and forensic traceability. However, the open distribution mechanism of AIGC exposes proprietary assets to risks of unauthorized replication and misuse. While watermarking offers a solution, existing schemes face a critical dilemma in IoT environments: they are either computationally expensive for edge deployment or structurally fragile against the dual threats of unpredictable IoT transmission failures and post-distribution image manipulations. To overcome these limitations, we propose Holo-Code, a robust and statistically lossless watermarking architecture based on a decoupled channel-coding paradigm. We introduce a holographic topological transformation to globally disperse watermark information across the latent representation. This mechanism mathematically converts structural data loss into uniform random erasures, which are robustly recovered via concatenated error correction coding. Furthermore, Holo-Code incorporates a distribution whitening mechanism that ensures the embedded signal is statistically indistinguishable from the standard Gaussian prior, thereby preserving the high fidelity of generated images. Extensive experiments validate that Holo-Code achieves a superior trade-off between robustness, quality, and efficiency. The framework guarantees reliable traceability across multiple generative models even under extreme composite degradations, seamlessly surviving heavy quantization from edge fallback mechanisms combined with severe structural occlusion. Moreover, as a training-free intervention, Holo-Code executes the complete forensic extraction on standard CPUs and achieves highly efficient identity retrieval against a database of one million users, establishing it as a practical solution for real-time AIGC provenance in large-scale IoT networks.

The rapid growth of blockchain technology and the increasing number of network nodes have heightened the risk of sophisticated attacks. Among these, Eclipse attacks present a serious threat to decentralized networks by exploiting their peer-to-peer structures. While previous research has explored artificial intelligence techniques to defend against Eclipse attacks, evolving attack patterns continue to challenge existing defenses. In this paper, we propose a novel defense framework that integrates a clustering approach based on self-attention encoders within a multi-kernel neural network clustering model. Our method utilizes parallel subnetworks to extract category-specific features from multiple perspectives, generating discriminative cluster centroids that are combined with raw transaction data to train a robust classifier for detecting Eclipse attacks in Ethereum networks. To evaluate our approach, we simulate Eclipse attacks on the Ethereum testnet and conduct extensive experiments. The results demonstrate that our method achieves a detection accuracy of 98.5% and improves classification performance by 5% compared to models trained without cluster-enhanced features, confirming the effectiveness of the proposed defense.

In low-altitude economy (LAE) networks, Artificial General Intelligence (AGI) models play a critical role in tasks such as path planning, object recognition, and task allocation. Support Vector Machine (SVM) models serve as fundamental components in AGI frameworks due to their robust capabilities in classification and regression tasks, which are essential for decision-making in LAE networks. However, distributed deployment and real-time inference of SVM models face significant challenges in security and privacy protection, including leakage of model parameters, exposure to data privacy, and reliability of prediction results. To address these issues, we propose a privacy-preserving and verifiable SVM prediction scheme (pvSVM) that can achieve the desirable properties of model privacy, data privacy, and private/public prediction verifiability. To be specific, we employ homomorphic encryption in conjunction with secret sharing to realize efficient and privacy-preserving model prediction in the edge. Then, we design two secure verification strategies to allow UAVs and any third party to check the correctness of predictions. To further support the verification of large-scale predictions, our scheme uses batch verification to reduce computational and communication overheads. Detailed analysis and extensive experiments prove the security and efficiency of our scheme.

To address the challenges of dynamic jamming and resource optimization in Unmanned Aerial Vehicle (UAV) confrontation communication networks, this paper proposes a hierarchical game framework for joint trajectory design and power allocation. These elements are inherently coupled: jamming degrades channel quality, prompting UAVs to adapt both their trajectories to improve spatial positioning and reduce jamming exposure, and their power allocation to maintain communication effectiveness under interference. The framework captures this interplay through a differential game for trajectory optimization and a Stackelberg game for power allocation, with the Nash equilibrium (NE) rigorously defined and its existence proved. To overcome the complexity of solving the Hamilton-Jacobi-Bellman equation, an adaptive dynamic programming algorithm is employed to approximate the value functions for both trajectory and power optimization. Simulations validate the effectiveness of the proposed framework, demonstrating that it accurately captures the strategic interactions between UAVs and provides robust decision support for resource optimization in dynamic adversarial environments.

With the rapid advancement of ubiquitous connectivity, the Internet of Unmanned Agents (IUA) has emerged as a promising paradigm for distributed intelligent perception and decision-making. In such systems, numerous unmanned agents collaboratively collect environmental data to support coordinated tasks. To preserve data privacy, Federated Learning (FL), as a decentralized machine learning framework, enables collaborative training of a global model across agents without directly exchanging raw data. However, FL faces several critical challenges in IUA environments, including high communication overhead under constrained wireless bandwidth, potential privacy leakage from shared model parameters, and agent dropouts caused by unstable connectivity. To address these challenges, we propose PPE-FL, a privacy-preserving and communication-efficient federated learning scheme designed for IUA scenarios. PPE-FL replaces conventional high-dimensional gradient uploads with lightweight ranking-based votes, substantially reducing communication overhead. Then, we design an obfuscation mechanism to protect the privacy of locally generated ranking-based votes, safeguarding both raw data and intermediate parameters. Furthermore, PPE-FL supports mask reconstruction through partial interactions among online unmanned agents, enabling robust aggregation under dynamic network conditions. Experimental results demonstrate that the proposed PPE-FL reduces communication costs by 89.5% compared to VCD-FL and by 87.7% compared to PPML, while maintaining model accuracy and privacy protection.

The rapid proliferation of Internet of Things (IoT) devices, coupled with their inherent security vulnerabilities, has significantly expanded the attack surface, intensifying threats such as man-in-the-middle attacks, traffic hijacking, and distributed denial-of-service (DDoS) attacks, thereby posing serious risks to the security and reliability of the entire ecosystem. The network traffic associated with IoT devices is diverse and dynamic, often exhibiting complex structural features such as periodic fluctuations, varying packet sizes, and time-varying patterns that make detection challenging. Although deep learning has demonstrated strong capabilities in efficiently identifying complex and dynamic malicious traffic through powerful feature extraction and adaptive learning abilities, its high model complexity, substantial computational demands, and large parameter sizes hinder direct deployment on resource-constrained IoT devices. In order to tackle this issue, this paper proposes a malicious traffic detection framework for the Internet of Things (IoT) based on multi-teacher knowledge distillation. The proposed model, termed the Lightweight Multi-Teacher Spatiotemporal Distillation Neural Network (LMT-SDNN), employs two high-performance teacher models: Residual Inception and a One-Dimension Convolution Netural Network (1D-CNN) integrated with idirectional Long Short-Term Memory (BiLSTM), to effectively capture the complex structural features of network traffic. Furthermore, a novel Time-Related Window Loss (TRW) function is design to enhance the student’s ability to capture temporal features, thereby improving its overall performance. The effectiveness of LMT-SDNN is validated through comparisons with five baseline models on two publicly available datasets, ToN_IoT and BoT_IoT. Experimental results show that LMT-SDNN achieves a compression rate of over 99% in both model complexity and parameter count, while maintaining an accuracy exceeding 99%, indicating its strong potential for multiclass malicious traffic detection in IoT environments.

Video analytics (VA) has become essential in applications, yet it poses significant challenges related to privacy preservation, network bandwidth, and computational resources. With the increasing deployment of high-definition cameras, privacy concerns and resource constraints are becoming critical barriers to the widespread adoption of VA systems. Existing privacy-preserving techniques are often static, inefficient, and fail to adapt to dynamic, real-time scenarios. In this paper, we propose Parachute, a dynamic, resource-aware and privacy-preserving video analytics system that adaptively switches between a local mode and a collaborative mode in response to traffic conditions. The system uses local reinforcement learning to enable each individual camera to operate independently, and switches to multi-agent reinforcement learning for coordinated optimization when local resources become limited. Experiments on real-world datasets demonstrate that Parachute effectively balances detection accuracy and privacy protection, outperforming baseline methods under bandwidth constraints.

Distributed Machine Learning (DML) enables parallel training but creates conflicts regarding model ownership determination, as verifying the specific contributions of individual clients during weight updates remains a challenge. To resolve ownership disputes and prevent malicious clients from forging data, verifying the integrity and effectiveness of each client's unique training history can fairly establish their partial ownership of the final DML model. In this paper, for the first time we propose a novel Matrix Commitment-based DML Ownership Verification (MAMMON) scheme that adopts a concise proof to ensure computational integrity and correctness within a limited computing cost. In contrast to computationally intensive SNARK-based approaches, MAMMON constructs a multi-linear tree structure to reduce proof update costs and avoids complex arithmetic circuit computations by standardizing the training process. Additionally, we watermark the weight proofs using client identity private keys to safeguard the commitments against tampering or unauthorized acquisition. Extensive experiments demonstrate MAMMON's superior performance in preserving computational integrity of DML training, covering both theoretical analysis and comparisons with other existing baselines.

Although federated learning prevents direct exposure of user data during training, numerous studies have demonstrated its vulnerability to security threats. Federated learning faces even greater risks due to its wide distribution, large number of users, and uncontrollable local data. Attackers can launch inference attacks to deduce users’ information from local model gradients. Furthermore, some malicious participants may launch poisoning attacks by tampering with local data or model updates. How to identify poisoning attacks while preserving user privacy in federated learning remains a major challenge, especially when the proportion of Byzantine clients is greater than or equal to 50%, which makes defense strategies harder to design. To address these challenges, we propose a robust federated learning aggregation scheme TCFL based on two-trapdoor homomorphic encryption. TCFL can preserve update privacy and prevent key leakage, and it can identify encrypted malicious gradients using a maximum clique filtering mechanism based on Euclidean distance. We provide convergence and security analyses of the scheme, and conduct extensive experiments on three benchmark image-classification datasets under multiple data and model poisoning attacks with attacker ratios ranging from 0% to 90%. The results show that, under these evaluated settings, TCFL maintains higher test accuracy and robustness than existing aggregation rules while retaining acceptable computational overhead.

The application of large language models(LLMs) in affective computing-ranging from empathetic chatbots to creative writing-has intensified the demand for distinguishing and authenticating AI-generated emotional content. Watermarking, by embedding detectable signals into the outputs of language models, offers a promising solution. However, a critical challenge persists: emotional texts often exhibit low entropy or complex spiky entropy distributions, which severely undermine the performance of existing watermarking methods. Unlike prior works that primarily treated spiky entropy as an external metric, we focus specifically on its role within the text generation process itself. To address the challenges of watermarking under low-entropy and complex entropy distributions, we propose DBW (Dynamic Bias Watermarking)-an entropy-aware watermarking algorithm for LLMs. DBW dynamically adjusts the watermarking bias in real time based on the entropy of each token. This innovation ensures a stronger watermark signal (increased green token count) in high-entropy contexts, while minimizing interference and quality degradation in fragile low-entropy emotional segments. Experimental results demonstrate that the proposed DBW algorithm outperforms the KGW watermarking method in both complex entropy distribution and low-entropy text generation scenarios. DBW achieves higher detection accuracy without sacrificing text quality. Furthermore, comparative experiments show that our proposed DBW algorithm demonstrates superior robustness under different attacks. Our work provides a reliable and adaptive tool for safeguarding emotion-AI generated content, contributing to the secure and trustworthy deployment of large-scale pre-trained models in affective computing.

Multi-view clustering aims to fully discover consistent clustering structures across different views, thereby improving the clustering performance. However, they usually lose structural information between different views during multi-view feature integration. Additionally, the misalignment of clustering centers from different views may lead to performance degradation. To tackle these challenges, in this paper, we propose a novel approach, called proxy-based dynamic view alignment with cross-view structure preservation (PDVA-CSP), for multi-view clustering. First, we design a graph aggregation module to explore the structure information between views through graph-based aggregation. Then we propose a proxy-based dynamic alignment strategy based on attention mechanisms to address the misalignment of proxies across views. Finally, we integrate them into an end-to-end learning framework, and then optimize it via a joint reconstruction loss and contrastive learning framework, seamlessly integrating feature extraction, view alignment, and clustering. The experimental results on several multi-view datasets demonstrate that the proposed PDVA-CSP method significantly outperforms other state-of-the-art methods in multi-view clustering tasks. The source code for this work will be available later.

Distributed Ledger Technology (DLT) has emerged as a promising solution for constructing decentralized and trustworthy platforms in recent years. Although blockchain, as a form of distributed ledger technology known for its tamper resistance and trustworthiness, seems to be an ideal solution for addressing trust issues, common blockchain systems face limitations due to the ever-growing volume of data. In this paper, we propose a dynamic storage scheme calledEfficiency-awareLow-storageScalability (ELS), which allocates variable data storage for the distributed ledgers. Our approach is designed to provide load balancing and security, allowing dynamic nodes to join or exit the network seamlessly. We utilize graph theory to group storage nodes in the blockchain by determining their network distances. These groups are then mapped into points in a two-dimensional virtual plane, meaning that block storage depends on the coordinates within the virtual plane. To balance storage performance with the evolving block allocation strategy, we develop a Voronoi diagram-based method to achieve near real-time adoptions that meet dynamic allocation requirements in blockchain systems. Experimental evaluations have demonstrated that our approach can reduce storage requirements by approximately 93% at each node, compared to full replication in 10000 block chains.

Asynchronous Byzantine fault-tolerant (BFT) protocols assuming no timing assumptions are inherently more robust than their partially synchronous counterparts, but typically have much weaker security guarantees.We design new and efficient asynchronous BFT protocols matching all security guarantees of partially synchronous protocols. To achieve the goal, we have developed the local coin based BFT approach–one long deemed as being inefficient–and designed more efficient asynchronous binary agreement (ABA) protocols and their reproposable ABA (RABA) versions from local coins. Notably, our techniques on ABA and RABA allow us to build more efficient ABA protocols from common coins.We implemented four BFT protocols in a new Golang library, including BEAT, two WaterBear protocols, and FlatWorm. The WaterBear protocols use the conventional BFT workflow, while FlatWorm leverages the framework separating message transmission from consensus and significantly improves the system throughput.Via extensive evaluation, we show that our WaterBear protocols and FlatWorm are efficient under both failure-free and failure scenarios. Notably, WaterBear-QS consistently outperforms BEAT across all metrics and FlatWorm significantly outpaces WaterBear-QS. For example, with 16 replicas, FlatWorm achieves a throughput of 213.04ktx/sec—5.63× that of BEAT and 3.43× that of WaterBear-QS.

Cluster-based side-channel analysis (SCA) is a commonly used side-channel analysis method for public key cryptography systems. This paper focuses on assessment metrics to improve the efficiency and accuracy of key recovery in cluster-based SCA processes. We introduce a novel metric called adjacent distance coefficient (AD coefficient). Different from traditional metrics like silhouette coefficient, membership degree, and information entropy, the AD coefficient, by considering local density and avoiding the computation of cluster centers, is less influenced by the shape and size of data, thereby overcoming limitations of traditional metrics. Experiments on RSA, SM2, and ECC demonstrate that the AD coefficient exhibits higher accuracy compared to traditional metrics, especially under conditions with noise and random delays, where it shows significant robustness. Incorporating the AD coefficient, we propose an assessment method to detect whether cryptographic devices are resistant to cluster-based SCA attacks, offering a convenient quantitative measure for the security evaluation of cryptographic devices.

The application of machine learning techniques in side-channel analysis has recently received increased attention. Finding the best hyperparameters to achieve optimal performance for machine learning models in side-channel analysis is still a challenging endeavor. In order to solve the problem, we present an efficient ensemble framework designed to support profiled side-channel analysis for attacking cryptographic devices with countermeasures. Our proposed framework can partially mitigate the impact of traditional countermeasures employed in cryptographic devices. Additionally, we introduce a novel voting method called elite voting, which leverages candidate keys with higher probabilities to recover the secret key and adjusts the voting weights for better candidate keys. Experimental results illustrate that our proposed framework can effectively recover the right key from cryptographic devices with countermeasures through multiple experiments. It enhances the signal-to-noise ratio of traces and successfully recovers the right key across various datasets. Furthermore, when compared to traditional methods, our elite voting method further enhances the performance of ensemble learning by reducing the number of traces needed to recover the secret key. It exhibits superior performance compared to other ensemble methods, as it can reduce the minimum required number of traces significantly.

Modular multiplication is one of the key operations in modern public-key cryptography. Montgomery Modular Multiplication (MMM) is a mainstream method to avoid modulo operations, which contains one variable multiplication and two constant multiplications. In this paper, for high performance, a novel Hybrid Truncated Montgomery Modular Multiplication (HTMMM) algorithm and its hardware architecture are proposed, which achieves state-of-the-art Area-Time-Product (ATP) and throughput. We propose an error-free high-part truncated multiplication for the first time, which solves the problem that conventional methods cannot be applied to MMM due to the introduced error, and reduces the complexity to the same level as low-part truncated multiplication. Besides, a hybrid multiplication based on Toom-Cook and Karatsuba is proposed to optimize variable multiplication, Non-Adjacent Form (NAF) encoding is adopted with truncated multiplication to optimize constant multiplications. The quantitative analysis of complexity for the integer multipliers with different schemes are illustrated to find the optimal multiplier under various cases. Based on these, we took the bit widthN= 1024 as an example to introduce the hardware architecture in detail and gave the implementation results ofN= 256 andN= 1024 in different processes. The experimental results demonstrate that compared with the best existing design, the throughput and ATP of our proposed design are improved by 1.25× and 2.22×, respectively.

Horizontal analysis is a widely adopted method in side-channel analysis, particularly for public-key cryptosystems, where attackers aim to recover the key from a single trace. Current methods rely on trace segmentation, dimensionality reduction, and classification, but high noise and poor feature preservation hinder accuracy. Noise blurs cryptographic operation segment boundaries, and existing dimensionality reduction techniques fail to maintain the inherent distribution of trace points in a high-dimensional space. As a result, secret information recovery based on clustering remains inaccurate. This paper proposes an automated horizontal analysis framework named UMAP-HC to improve secret information recovery accuracy. The framework employs a sliding segmentation method to locate cryptographic operations in noisy traces with blurred segment boundaries. It leverages uniform manifold approximation and projection (UMAP) for feature preservation and hierarchical clustering for secret information recovery. Experimental results on four open access public-key algorithm power trace datasets, an SM2 power trace collected from a smart card, and an ECC power trace with dummy operation countermeasures demonstrate that UMAP-HC effectively classifies cryptographic operations, accurately locates operation segments, and recovers secret key. It achieves up to 100% recovery accuracy, surpassing previous methods by 40%-70%, with normalized mutual information reaching 1, an improvement of 0.02-0.99 over existing approaches.

Multi-scalar multiplication (MSM) is the primary computational bottleneck in zero-knowledge proof protocols. To address this, we introduce FAMA, an FPGA-oriented MSM accelerator developed through algorithm-hardware co-optimization. By integrating a 3D-Pippenger optimization algorithm, FAMA minimizes computational complexity, while its compact dual-mode point addition (PADD) unit significantly reduces hardware overhead. Compared to the best CPU-based design, FAMA achieves over 184.20× speedup. It also outperforms state-of-the-art FPGA-based MSM accelerators, reducing resource overhead by more than 64% and boosting area-time product (ATP) by up to 37.09×.

We study feature selection (FS) for flow-based intrusion detection and propose a deterministic hybrid-FS that fuses Mutual Information, Random-Forest, and XGBoost importances under a simplex search with a single threshold. Using CIC-IDS-2017, CSE-CIC-IDS2018, and NF-UNSW-NB15, we evaluate ten FS techniques paired with six ensembles under a leakage-safe protocol. The hybrid-FS consistently matches or exceeds the best single selectors while reducing feature count (e.g.,$78 \rightarrow 31$) and improving runtime. Throughput rises by$\sim$9–10% and per-flow latency drops from$0.44 \rightarrow 0.40$ms (p50) and$1.40 \rightarrow 1.20$ms (p99), with mean$\pm$95% CIs and paired tests. False-positive rate (FPR) decreases by 15–19% ($\approx$22 fewer false alarms per hour at 100k flows/h). Against representative PSO/GA hybrids, our fusion attains small but consistent macro-F1 gains and 15–25% FPR reductions at comparable latency. We clarify adversarial robustness with an explicit FGSM feature-space threat model and DeepPackGen configuration, and we diagnose cross-dataset shift with lightweight mitigations. A 24-hour SOC replay links FPR to analyst time savings (2.5–3.7 hours/day) without sacrificing macro-F1 or AUROC. The results position deterministic, compact FS as a practical choice for inline IDS where tail latency and alert volume matter.

Blockchain-based steganography enables data hiding via encoding the covert data into a specific blockchain transaction field. However, previous works focus on the specific field-embedding methods while lacking a consideration on required field-generation embedding. In this paper, we propose a generic blockchain-based steganography framework (GBSF). The sender generates the required fields such as amount and fees, where the additional covert data is embedded to enhance the channel capacity. Based on GBSF, we design a reversible generative adversarial network (R-GAN) that utilizes the generative adversarial network with a reversible generator to generate the required fields and encode additional covert data into the input noise of the reversible generator. We then explore the performance flaw of R-GAN. To further improve the performance, we propose R-GAN withCounter-intuitive data preprocessing andCustom activation functions, namelyCCR-GAN. The counter-intuitive data preprocessing (CIDP) mechanism is used to reduce decoding errors in covert data, while it incurs gradient explosion for model convergence. The custom activation function named ClipSigmoid is devised to overcome the problem. Theoretical justification for CIDP and ClipSigmoid is also provided. We also develop a mechanism named T2C, which balances capacity and concealment. We conduct experiments using the transaction amount of the Bitcoin mainnet as the required field to verify the feasibility. We then apply the proposed schemes to other transaction fields and blockchains to demonstrate the scalability. Finally, we evaluate capacity and concealment for various blockchains and transaction fields and explore the trade-off between capacity and concealment. Experimental results demonstrate that R-GAN and CCR-GAN are able to enhance the channel capacity effectively and outperform state-of-the-art works.

Federated learning (FL) offers a decentralized, privacy-preserving framework for encrypted traffic classification (ETC), enabling network management and security. However, real-world deployment of federated ETC faces compound client specific feature, concept, and label drift, which degrades model performance. Existing ETC methods under FL settings typically address these drift types in isolation or partial combinations, overlooking their entanglement. Moreover, multiple-global model and personalized FL approaches are computational and communication expensive. To fill this gap, we propose DAIR FedMoE, a Drift-Adaptive, Imbalance-Aware, RL-Managed Federated Mixture-of-Experts framework to simultaneously handle the drift triad with single-global model while minimizing the computational and communication overhead. DAIR-FedMoE in tegrates a GShard Transformer with a hierarchical Mixture of-Experts (MoE) layer that routes encrypsted flows to either stable or drift-specialist experts based on per-client drift scores. Within each expert, entropy-guided loss reweighting empha sizes low-confidence classes to address dynamic label imbalance. Additionally, a reinforcement learning-based policy dynamically manages the expert pool by spawning, pruning, and merging experts, enabling efficient adaptation to evolving traffic patterns. Experiments on federated splits of ISCX-VPN, ISCX-Tor, VNAT, and USTC-TFC2016 show that DAIR-FedMoE achieves superior macro-F1, minority-class recall, and drift-recovery speed compared to state-of-the-art baselines, while preserving privacy and communication efficiency. The source code is available at https://github.com/dairfedmoe/DairFM.

This paper presents Hydra, a dynamic BFT protocol that allows replicas to join and leave the system dynamically. It addresses the limitations of traditional static BFTs in managing membership changes and can be used to simplify the implementation of many features in modern blockchain applications. Hydra relies on weaker assumptions to achieve standard properties compared to the existing solution Dyno and introduces a configuration auto-transition protocol to ensure liveness. Through temporary configurations and explicitly defined replica responsibilities for request handling, Hydra pipelines membership requests alongside regular requests and realizes clarity, achieving a more efficient and smoother configuration transitions. It also employs a non-blocking configuration discovery mechanism, enabling new replicas to participate in consensus quickly. We formally prove Hydra's correctness under the dynamic BFT model. Experimental results demonstrate Hydra's ability to maintain throughput fluctuations within 5% during various replica join and leave scenarios, outperforming Dyno and existing BFT system supporting reconfiguration in both stability and efficiency. Hydra effectively manages scenarios that Dyno circumvents with stronger assumptions and quickly restores throughput to normal levels.

Graph Neural Networks (GNNs) have been widely used in various domains, such as social networks and transportation networks. Previous research has shown that GNNs are vulnerable to inference attacks. Node Membership Inference Attacks (NMIA) on GNNs infer whether a set of graph data records belongs to the training graph data of a target model. Link Status Inference Attacks (LSIA) against GNNs aim to infer whether there exists a link between a pair of nodes in the graph used to train the target GNN model. Specifically, given black-box access to a GNN model, NMIAs and LSIAs are conducted by analyzing the outputs (e.g., confidence score vectors) from GNN models. The defense methods against these two score-based inference attacks face the challenges of achieving effective defense performance and maintaining the utility of GNN models. In this paper, we propose PriGraph, a defense mechanism to protect the node privacy and link privacy of training graph data, while maintaining the high accuracy of the target GNN models. PriGraph adds crafted adversarial perturbations to outputs of the target GNN model by deploying two key components, i.e., defense auxiliary classifier and adversarial perturbation generator, which are used to find the minimal adversarial perturbations that can reduce the attack accuracy while maintaining task performance of node classification. We evaluate PriGraph with different GNN models and multiple benchmark datasets. The results show that PriGraph can dramatically reduce the attack accuracy of NMIA and LSIA on GNNs, providing a superior trade-off between the model utility and privacy.

Buy Now Pay Later (BNPL) is a rapidly proliferating e-commerce model, offering consumers to get the product immediately and defer payments. Meanwhile, emerging blockchain technologies endow BNPL platforms with digital currency transactions, allowing BNPL platforms to integrate with digital wallets. However, the transparency of transactions causes critical privacy concerns because malicious participants may derive consumers' financial statuses from on-chain asynchronous payments. Furthermore, the newly created transactions for deferred payments introduce additional time overhead, which weakens the scalability of BNPL services. To address these issues, we propose an efficient and privacy-preserving blockchain-based asynchronous payment scheme (Epass), which has promising scalability while protecting the privacy of on-chain consumer transactions. Specifically, Epass leverages locally verifiable signatures to guarantee the privacy of consumer transactions against malicious acts. Then, a privacy-preserving asynchronous payment protocol is further constructed by leveraging time-release encryption to control trapdoors of the redactable blockchain, reducing time overhead by modifying transactions for deferred payment. We give formal definitions and security models, generic structures, and formal proofs for Epass. Extensive comparisons and experimental analysis show that Epass achieves KB-level communication costs, and reduces time overhead by more than four times in comparisons with locally verifiable signatures and Go-Ethereum private test networks.

Cross-domain authentication is essential for se curing communication between different management domains in Vehicular Ad Hoc Networks (VANETs). However, existing blockchain-based cross-domain authentication schemes, which rely on centralized entities or smart contracts for distributed identity management, face challenges in terms of latency, trust assumptions, security guarantees, and deployment flexibility. Furthermore, many of these schemes do not fully meet the stringent regulatory requirements of real-world VANET sce narios and provide limited protection of vehicle privacy. In this paper, we introduce BCADS, a Blockchain-assisted Cross domain Authentication with Decentralized identity for VANETs under Strict oversight. BCADS enables vehicles to autonomously generate and manage their identifiers, eliminating reliance on a single centralized authority and mitigating single points of failure by jointly maintaining identity records on a consortium blockchain infrastructure. In addition, BCADS is designed to accommodate regulatory mandates while protecting user privacy and data confidentiality. The scheme addresses key limitations of prior designs by supporting flexible identity management and strong privacy protection within a practical architecture. Security analysis shows that BCADS withstands a broad range of attacks and achieves the desired security properties. Performance measurements and simulation experiments indicate that BCADS reduces computational costs by up to 36.6% and communication costs by up to 87.1%, demonstrating its practicality for deployment in real-world VANETs.

Vision Transformers (ViTs) have emerged as a dominant backbone architecture for a variety of visual tasks; however, their vulnerability to adversarial examples continues to pose a significant challenge. Unlike Convolutional Neural Networks (CNNs), ViTs fundamentally rely on self-attention mechanisms, leading to a distinct architectural design. The limited transferability of existing adversarial attacks on ViTs can be attributed to the neglect of these unique features. To address this, we introduce a novel self-attention-oriented Adversarial Block Skip (ABS) method specifically designed to generate transferable adversarial examples. ABS aims to create a diverse range of structures by applying skip connections to blocks within the transformer encoder, thereby activating the uncertainty of the attention mechanism. This disrupts the global interaction between different features captured by ViTs, thereby confounding the model's decision-making process. The results unequivocally demonstrate that the ABS not only establishes a versatile and efficacious attack mechanism but also supports transfer attacks across a diverse array of ViTs and CNNs. This finding emphasizes the significant generalization capabilities of ViTs within the adversarial landscape, suggesting that their resilience and adaptability under such conditions may surpass previous assumptions. Comprehensive empirical evaluations involving various prominent transformer models on the ImageNet dataset substantiate that ABS markedly surpasses existing baseline methods in terms of effectiveness. Furthermore, ABS is highly compatible with prevailing adversarial attack frameworks, augmenting their efficacy upon integration. Such versatility renders ABS an indispensable component of the toolkit for executing advanced and effective adversarial attacks in the realm of machine learning security.

As cryptocurrency prices continue to recover, crypto crimes such as money laundering are becoming increasingly rampant. Mixing services such as Tornado Cash have become the primary tools for obfuscating illegal financial transactions due to their inherent anonymity mechanisms. Tornado Cash is a non-custodial, smart contract-based mixing service (SC-CMS) that breaks the direct mapping between deposit and withdrawal accounts, hindering regulators from tracking illicit fund flows. Existing deanonymization methods for Tornado Cash suffer from several challenges, including vague theoretical concepts, evolving mixing mechanisms, and insufficient labeled samples. To address these concerns, this paper proposes the first formal concept of SC-CMS to facilitate and evaluate the deanonymization efforts systematically. We design a novel linkability attack, LASC, based on enhanced graph structure learning, to associate mixing accounts on Tornado Cash and mathematically prove its feasibility. Comprehensive experiments on real Ethereum transactions demonstrate that LASC outperforms state-of-the-art works in both performance and efficiency.

Blockchain transaction verification is fundamental to decentralized financial applications, ensuring both transaction authorization and integrity. Most existing verification schemes utilize an equal weight model that grants identical rights to all participants. However, these schemes fail to capture real-world scenarios like Proof-of-Stake blockchains, where participants have right discrepancies. Additionally, many schemes depend on trusted third parties for key generation, introducing single points of failure and compromising security. To address these limitations, we propose WBlock that is a weighted and decentralized verification scheme. WBlock involves a distributed key generation protocol that embeds each entity's weight into its secret share, eliminating the need for trusted third parties. It further employs a Schnorr-type weighted threshold signing protocol, enabling distributed transaction authorization while reflecting participant weight in signature shares. Security analysis shows that WBlock achieves both correctness and unforgeability. Comparative theoretical analysis shows that our key generation and signing protocols outperform existing methods in terms of round complexity, communication overhead and data size. Experimental results confirm that WBlock achieves a balance between security and efficiency, with acceptable overhead for real-world blockchain deployment.

Recent booming development of Generative Artificial Intelligence (GenAI) has facilitated model commercialization to reinforce the model performance, including licensing or trading Deep Neural Network (DNN) models. However, DNN model trading may violate the benefit of the model owner due to unauthorized replications or misuse of the model. Model identity auditing is a challenging issue in protecting DNN model ownership, and verifying the integrity and ownership of models is one of the critical obstacles. In this paper, we focus on the above issue and propose anAccumulator-enabledAuditing forDecentralizedIdentity of DNNModel (A2-DIDM) that utilizes blockchain and zero-knowledge techniques to protect data and function privacy while ensuring the lightweight on-chain ownership verification. The proposed model presents a scheme of identity records via configuring model weight checkpoints with zero-knowledge proofs, which incorporates predicates to capture incremental state changes in model weight checkpoints. Our scheme ensures both computational integrity and programmability in DNN training process so that the uniqueness of the weight checkpoint sequence in a DNN model is preserved. A2-DIDM also addresses privacy protections in decentralized identity. We systematically analyze the security and robustness of our proposed model and further evaluate the effectiveness and usability of auditing DNN model identities. The code is available athttps://github.com/xtx123456/A2-DIDM.git.

Covert communication over public blockchains has emerged as a promising approach for secret data transmission. However, existing methods often suffer from high communication costs, low communication efficiency, and the risk of permanent data exposure. To overcome the above challenges, we propose FastBOC, a hybrid covert communication framework that integrates blockchain and onion networks. In FastBOC, the blockchain is employed as a covert signal channel to transmit lightweight signals, while the onion network handles high-capacity secret data transmission. This decoupling significantly reduces communication costs and avoids permanent data exposure on the blockchain. We further design an address-based encoding scheme and a dynamic port activation mechanism to enhance concealment. We implement FastBOC on the Ethereum testnet and conduct experiments to evaluate its concealment, efficiency, and cost. The results demonstrate that FastBOC (1) achieves strong concealment and (2) can transmit 1-Megabyte (MB) data within 20.11 seconds and reduce communication cost by 5–7 orders of magnitude compared to prior blockchain-based covert communication schemes.

Smart contracts play a pivotal role in blockchain ecosystems, and fuzzing remains a critical approach to securing them. However, existing smart contract fuzzers often optimize either seed generation or mutation scheduling in isolation and rely on narrow, fragmented feedback signals, leaving multi-transaction reasoning and stagnation recovery under-explored. In this work, we propose aLarge Language Models(LLMs)-based Multi-feedback Smart Contract Fuzzing framework (LLAMA). Key components of the proposed LLAMA include: (i) a hierarchical prompting strategy that guides LLMs to generate structurally valid, context-aware multi-transaction initial seeds, together with a lightweight pre-fuzzing phase that validates and prioritizes high-potential LLM-generated candidates; (ii) a multi-feedback-guided evolutionary optimization module that jointly optimizes seed selection and mutation scheduling by a group of constraints for driving an LLM-bootstrapped bandit scheduler. (iii) an LLM-guided hybrid fuzzing module that integrates evolutionary fuzzing with a dual-channel recovery mechanism, which concurrently employs asynchronous coverage-stagnation- based LLM reseeding and selective symbolic execution to resolve complex path constraints. Our extensive experiments demonstrate that LLAMA outperforms state-of-the-art fuzzers in both coverage and vulnerability detection. Specifically, it achieves 92% instruction coverage on small contracts and 81% on large contracts, while detecting 132 out of 148 known vulnerabilities across diverse categories. Ablation studies further evidence that the proposed multi-feedback and hybrid recovery strategies have strong impact on LLAMA’s performance. The results explain LLAMA’s effectiveness, adaptability, and practicality in complex smart contract scenarios.

Recommendation systems based on graph neural networks (GNNs) have emerged as a promising paradigm due to their ability to capture high-order interactions between users and items. However, in federated scenarios, this advantage is compromised, as each user can access only a first-order subgraph composed of its directly interacted items. To address this issue, most existing solutions introduce a trusted server to assist users in expanding their local subgraphs. However, the server in reality is often untrusted and may deviate from the protocol for its own improper benefit. Furthermore, these solutions primarily focus on the privacy of items while neglecting the privacy of potential relationships between users. To this end, we propose Garland, a GNN-based federated recommendation scheme with malicious security. Garland departs from existing work by ensuring both item and relationship privacy while supporting integrity checks to defend against malicious servers. Specifically, we employ a trending cryptographic primitive of secret-shared shuffle to expand subgraphs in a privacy-preserving and verifiable manner. We also design a pre-shuffle triple-salt encryption mechanism and a post-shuffle user-governed expansion mechanism to reduce communication costs and achieve secure distribution of neighbor information, respectively. Moreover, we develop a secret-shared aggregation mechanism to enable privacy-preserving and verifiable federated training. Theoretical analysis demonstrates the privacy and integrity of Garland. Extensive experimental evaluations on four datasets show that Garland outperforms state-of-the-art solutions.

Malware widely adopts network traffic encryption techniques to conceal malicious activities. Recent research has demonstrated the effectiveness of machine learning (ML)-, deep learning (DL)-, and pre-training-based malware traffic detection methods. However, a vast majority of these methods rely on the collected complete traffic during the malware attack. While certain methods can operate on partial traffic, their detection accuracy often significantly decreases when the available data is restricted to the extreme early stage, where information is most sparse. In this paper, we proposeDawnGuard, an effective early-stage encrypted malware traffic detection framework through multi-flow temporal graph learning. Specifically, based on the temporal packet density distribution analysis,DawnGuardinnovatively proposes a self-adjusting data augmentation strategy for early-stage malware traffic, which can force the model to focus on the early-stage interaction phase with more distinguishable properties. Meanwhile, considering that temporal-topological correlations among multiple flows can provide more distinguishable properties in a malware attack, we further develop a temporal graph learning framework to extract features, which can formMulti-Flow Graph Features (MGF). By utilizingMGF,Dawn-Guardimplements a Vision Transformer-based detection mechanism, enabling accurate and precise encrypted malware traffic detection with early-stage traffic by capturing both local and global contextual relationships. Extensive experiments with two real-world datasets demonstrate thatDawnGuardoutperforms the state-of-the-art (SOTA) methods in three typical scenarios: varying early-stage time windows, imbalanced data, and unseen malware detection. Particularly,DawnGuardachieves an average F1 of 95.11%, 8.7% higher than the SOTA method, by only utilizing the first 20% loading ratio of complete traffic.

Blockchain-based electronic voting systems can achieve voter identity anonymity via cryptographic techniques such as ring signatures and blind signatures. However, fully hiding of voter information mitigates the capability of traceability. Previous mechanisms provide limited traceability, typically by preventing double-voting attacks while compromising the anonymity. From the cryptographic point, threshold signature with private accountability seems to offer a balanced solution between privacy and accountability. If directly applying it into blockchain-based electronic voting systems, it needs to fix all voters and each verification has to pre-store all voters’ public keys, incurring at least linear-size storage overhead and poor scalability. How to optimize the storage and scalability while guaranteeing both anonymity and traceability remains to be challenging. In this paper, we propose BAVote, an efficient and scalable blockchain-based electronic voting system with anonymity and traceability. It is built on top of a new threshold signature scheme named ConsATS that features a constant-size verification key. ConsATS compress all voters’ public keys into a single verification key, allowing an aggregated ballot to be verified without storing or processing per-voter public keys, thereby reducing on-chain storage overhead and improving scalability in BAVote. The aggregated signature serving as the ballot is encrypted in ConsATS, while BAVote further combines one-time addresses and a commit–reveal mechanism to protect intermediate on-chain data during voting. The corresponding tracing key enables authorized tracer to identify malicious voters during authorized audits. We implement a prototype of BAVote in both a local blockchain environment and the Ethereum Sepolia testnet. The experimental results show that the storage cost of verification keys in our system is reduced by more than 90% and the verification time is 7x faster compared to existing schemes.

Graph-based vertical federated learning (GVFL) enables an active party who owns a labeled graph to collaborate with passive parties who possess additional node features and edges to improve model performance. GVFL shares representations and gradients, allowing passive parties to retain their optimized bottom models, which makes previous GVFL algorithms unable to resist label inference attacks. However, most attacks assume that the attacker has access to the training data’s exact class space, the top model, or labeled auxiliary datasets from the training domain. These strong assumptions are not practical for real-world GVFL applications. In this paper, we propose Knowledge Transfer Attack (KTA), which leverages only auxiliary graphs from non-training domains to infer private labels. To address domain shift and ensure effective supervision transfer, KTA adapts a surrogate classifier in an aligned representation space while mitigating the negative influence of irrelevant outlier-class supervision. Specifically, KTA exploits the global consistency of cross-domain graphs and incorporates adaptive shift parameters into graph encoding. KTA then aligns cross-domain distributions within the shared class space and mitigates negative transfer by filtering outlier source classes. Experiments confirm the effectiveness of KTA in inferring the active party’s private labels and superiority over state-of-the-art attacks.

Vertical Split Federated Learning (VSFL) allows participants to collaboratively train a better model with different features vertically partitioned in the same sample space, where the model is divided into bottom model and top model by the cut layer, trained by passive and active participants respectively. However, in the process, the labels owned by the active participant will still be inferred or stolen by curious or malicious passive participants. In this paper, we propose Casper, a causality-inspired defense mechanism with a confounder against label inference attacks in VSFL. Casper first analyzes the feasibility of optimizing the training process in VSFL at the intervention level from a causal perspective. It then introduces a confounder consisting of cut layer output reconstruction and label obfuscation to disrupt the direct causality between cut layer outputs and labels. Additionally, we integrate selective discrepancy training to further ensure model utility by strategically balancing training between active and passive participants. Extensive experiments conducted on four datasets across different tasks demonstrate that Casper effectively preserves label privacy while maintaining model performance, significantly outperforming current advanced defending methods in VSFL.

Asynchronous federated learning (AFL) accelerates collaborative training across heterogeneous devices compared to synchronous federated learning, but increases vulnerability to Byzantine attacks due to its asynchronous aggregation. Existing defenses rely on parametric similarity between models and temporal consistency of updates, which are compromised by data and device heterogeneity, leading to ineffective robustness. To address this limitation, we propose Belisa, a Byzantine-robust AFL framework that enhances fidelity, robustness, and efficiency under heterogeneous scenarios. Belisa introduces novel discrepancies between feature representations of local models to distinguish malicious models from benign ones. By leveraging a reference model trained on publicly available data, Belisa quantifies these discrepancies, referred to as feature fingerprints, and filters out malicious models through clustering. Extensive experiments on six datasets from three types of tasks under five advanced Byzantine attacks demonstrate Belisa’s superiority. Notably, Belisa consistently outperforms existing approaches across both attack and non-attack settings. Under attack scenarios, it lowers the average test error rate to 0.42× that of baseline methods. Furthermore, Belisa accelerates the aggregation process by an average of 12.3× compared to other methods. To the best of our knowledge, Belisa is the first Byzantine-robust AFL framework, which provides a broadly applicable countermeasure in heterogeneous scenarios which are more prevalent in real-world settings.

Simple Power Analysis is a commonly used method in Side-Channel Analysis on cryptosystems, which requires a significant amount of labor costs for segmentation. General Pulse Tailor for Simple Power Analysis (SPA-GPT) proposed in CHES 2024 utilizes reinforcement learning to achieve automated segmentation. However, its low efficiency and only targeting public-key algorithms limit its practical applications. In this paper, we propose a practical method, which utilize long short-term memory network and attention mechanism, coupled with a new deep Q-network policy using Simulated Annealing strategy, to solve the contradiction between reinforcement learning and high efficiency in trace segmentation. Moreover, the novel agent proposed in this paper also demonstrates transferability, enabling direct segmentation of a trace under varying lengths and signal-to-noise ratio conditions once the agent has been fully trained. In addition, our new approach is applicable for locating each execution of block ciphers in various encryption modes. Comparative experiments are conducted on 14 datasets, which are collected from software or hardware implementations of RSA, ECC, ML-KEM, AES, PRESENT, and SIMON, running on microcontrollers, FPGAs, or smart cards. Experimental results show that the new method enhances time efficiency by 50.34% to 94.24% while reducing network parameters by 87.84% compared to SPA-GPT.

Local Differential Privacy (LDP) enables privacy-preserving data analytics without requiring a trusted aggregator and has attracted significant attention from both academia and industry. For key–value data, PrivKV has been proposed to support frequency and mean estimation under LDP. In PrivKV, the user first samples a key uniformly at random and applies a randomization mechanism to perturb the corresponding value. However, since both Sample and Perturb steps are conducted locally, PrivKV is susceptible to output poisoning attacks, where malicious users bypass these steps and submit crafted data, making the aggregation result biased. To address this vulnerability, we propose VPrivKV, a verifiable LDP protocol designed to defend against output poisoning attacks. VPrivKV enables users and the aggregator to jointly perform the sampling step using a coin-flipping protocol, while the perturbation is enforced through an interactive and verifiable mechanism. Furthermore, we propose an enhanced version of VPrivKV that integrates zero-knowledge proofs to prevent the adversary from forging the discretized value to suppress non-target keys, thereby further enhancing robustness. We theoretically analyze the privacy and robustness of the proposed protocols and conduct numerical simulations to demonstrate their effectiveness in defending against output poisoning attacks.

To meet personalized user demands, customized and personalized production (CPP) has become an effective manufacturing paradigm. However, wired network connections inhibit flexible production line reconfiguration and current DRL methods cannot converge and obtain eligible scheduling results for CPP due to the high-dimensional solution space and the negligence of significant machine reconfiguration time. To address this challenge, we first propose a wireless manufacturing system framework to support ultra-flexible reconfiguration and resource scheduling. Next, we build a reconfiguration oriented scheduling model to reflect the significant impact of reconfiguration time. Then, we design a knowledge guided deep reinforcement learning algorithm to effectively solve the CPP scheduling problem facing the dimension explosion problem. The knowledge guidance incorporates reconfiguration time and machine workload to significantly reduce the feasible action space, enabling the rapid convergence of KGDRL. The experiment results show that our approach provides a robust and scalable solution and obtains shorter total makespan of whole production during scheduling.

As terrestrial resources become increasingly saturated, the developing attention is gradually shifting from the ground to the low-altitude airspace, which supports many emerging applications such as urban air taxis and aerial inspection. For these applications, low-altitude wireless networks (LAWNs) are the foundation, with integrated sensing, communications, and computing (ISCC) being one of the core parts. However, the openness of low-altitude airspace poses a serious threat to communications, degrading ISCC performance and ultimately compromising the reliability of applications supported by LAWNs. To address these challenges, this paper studies joint performance optimization of ISCC while considering security of the communications. Specifically, we derive beampattern error, secrecy rate, and age of information (AoI) as performance metrics for sensing, secure communication, and computing. Building on these metrics, we formulate a multi-objective optimization problem, which aims to balance sensing and computing performance while enhancing the secrecy rate of communications. We then propose a deep Q-network (DQN)-based multi-objective evolutionary algorithm, which adaptively selects evolutionary operators according to the evolving optimization objectives, thereby leading to more effective solutions. Extensive simulations show that the proposed method brings an average performance gain of about 14% compared to existing methods, thereby ensuring ISCC performance for applications supported by LAWNs.

Nowadays, mobile cloud storage has become increasingly prevalent for processing mobile data due to its convenience and resources. Towards the right to restriction of processing in current data regulations, some solutions have been proposed to empower data owners with identity-based hierarchical control for equality, comparison, and plaintext analytics operations. However, existing solutions either rely on specific hardware environments (i.e., trusted execution environments) or face two significant issues: identity privacy breaches, where attackers can identify targeted users, and excessive overhead in multi-user scenarios, as each user requires a distinct ciphertext. In this paper, we leverage multiple cryptographic primitives to introduce PODS, an efficient and secure hierarchical data processing control scheme for multi-user mobile cloud storage. PODS allows the data owner to generate a single ciphertext for multiple users without hardware reliance. Technically, we reconstruct identity-based encryption by leveraging well-designed common and private parameters, thereby shifting the focus from data itself to data processing operations. Then, we encode multiple targeted identities as polynomial coefficients and integrate these coefficients into identity-based data processing control. We achieve threefold benefits, effectively reducing overhead, hierarchically processing users' rights, and concealing the identities of targeted users to protect privacy. Security analysis proves the security of PODS. Experiments demonstrate that PODS achieves around$8\times$and$37\times$improvement in computation and communication compared to existing related works.

The unprecedented advancements in quantum technology have opened new prospects for the widespread adoption of quantum applications, placing new demands on the information transmission capabilities of large-scale quantum networks. Long-distance and stable entanglements are deemed as the lifeline in quantum network communication. However, some weaknesses, e.g., quantum decoherence, scarce quantum memory, and uneven-quality entanglement, of the quantum entanglement hinder the development. In this paper, we proposeSophon, an online transmission framework for quantum networks, which utilizes high-dimensional entanglements to concurrently transmit multi-qubit data to satisfy the transmission requirements of the real-time request set. We first model the quantum network with multi-qubit entanglement represented by$W$quantum state and then formulate the Entanglement Routing and Qubit Provisioning (ERQP) problem as a global-local optimization process. To solve theERQPproblem, we distributedly regard each network node as an RL agent for resource provisioning and extend the step-updating of the Markov Decision Process by introducing a centralized controller for entanglement route selection to optimize local and global objectives, respectively. Extensive simulations demonstrate, on the self-made simulation platform,Sophonachieves a$21.89\%-66.52\%$decrease in the communication cost, and is more robust on different scales of the network topology and the request set than the baselines.

In recent years, volumetric videos have gradually prospered as an intriguing video paradigm, offering users a fully immersive viewing experience with six Degrees of Freedom (DoF). However, most current live volumetric video streaming methods struggle to facilitate the real-time performance requirements due to the nature of frequent user interactions and the complexity of network environments during video playback. Inspired by the correlation between the human visual effects and adjacent frame motion features, we proposeCetus, a context-aware cross-layer coordination system for live volumetric videos. First, we present an application-layer Neural Radiance Fields (NeRF)-based codec framework that leverages spatio-temporal semantic information for optimizing the compression quality of each video frame. Second, we exploit a flexible cross-layer coordination framework that seamlessly integrates frame drop strategy with partially reliable transmission, orchestrating transport protocols and application-informed rates to enhance the Quality of Experience (QoE) for multiple users. Furthermore, we develop a lightweight branching decision tree algorithm that adaptively makes fine-grained frame drop decisions. Experimental evaluations of our implemented system prototype demonstrate that Cetus significantly outperforms existing baseline approaches. Compared to the state-of-the-art baselines, Cetus effectively improves video frame rate by at least 24.7% and video quality by an average of 32.6%.

Byzantine fault-tolerant (BFT) consensus protocols are the core components of blockchain. In the process of improving the performance of BFT protocols, existing work faces the following three problems: 1) the binary dilemma between the leader’s performance bottleneck in star-based linear communication and compromised resilience in tree-based sublinear communication; 2) two- or three-round protocols restrict the phase number of one proposal, thereby limiting the number of concurrent proposals and causing high latency. 3) The fixed timeout makes the protocol sensitive to varying network delays. Therefore, this paper proposesCrackle, the first sector-based pipelined BFT protocol with a sublinear communication complexity, for a throughput improvement of consensus protocol with max resilience of$(\mathcal {N}\textrm {-} 1)/3$. We propose a sector-based communication mode to disseminate messages from the leader to a subset of replicas in each phase to accelerate consensus and split the traditional two-round protocol into$2\mathsf {\kappa }$phases to increase the basic pipeline scale. We refine the timer strategy so that the timeout$\Delta $is adjusted with the proposal submission to cope with the changing network environment. We then address two technical challenges: 1) to ensure Quorum Certificate (QC) validation, we design a$\mathit {voteMap} s$field within each block, and verify QC by the signature aggregation of$\mathit {voteMap} s$in continuous$\mathsf {\kappa }$phases; and 2) to achieve pipeline decoupling among shorter phases, we propose a vote-appending mechanism that relaxes the conditions for the leader to send new proposals. We provide comprehensive theoretical proof of the correctness ofCrackle, including safety and$\mathit{liveness}$. Moreover, we implementCracklebased on a public BFT framework and deploy it on 64 cloud servers. Real experimental results reveal that ourCrackleprotocol achieves up to 10.36x higher throughput and can dynamically adapt to network delay compared with state-of-the-art BFT protocols such as Kauri and Hotstuff.

Serverless computing promises fine-grained resource elasticity and billing, making it an attractive way to build complex applications as multi-stage workflows. Nonetheless, existing workflow orchestration ignores the heterogeneous demands of the computation and communication parts within a stage, potentially resulting in resource inefficiency on either side. In this paper, we advocate forcomputation-communication-separated orchestrationto unleash hybrid resource (i.e., compute and network) elasticity. We present HyFaaS, a serverless workflow orchestrator that improves performance while ensuring cost efficiency. It seamlessly decouples computation and communication as a series of hybrid stages re-expressed within HyDAG, a novel workflow abstraction. HyFaaS uses a gray-box profiling model to identify their Pareto-optimal saturated configurations, and then deploys the saturated workflow to juggle communication and scaling overheads through two-level HyDAG partitioning. Along with event-driven runtime fine-tuning, HyFaaS further scales down the non-critical stages to reduce cost via branch-aware coordination. Experimental results show that HyFaaS surpasses existing solutions by 32.7%–50.4% on end-to-end latency, while lowering cost by up to 1.37×.

Dynamic Searchable Symmetric Encryption (DSSE) plays a crucial role in secure cloud-based database systems, as it enables efficient keyword search and dynamic updates over encrypted data. However, practical deployment of DSSE schemes faces two significant challenges. First, clients may inadvertently perform faulty updates—such as re-adding an existing keyword-identifier pair or attempting to delete a non-existent one—which can compromise the correctness of subsequent search results. Second, even with correctly issued updates, malicious servers may return incorrect or incomplete search results, undermining data integrity. To address these challenges, we propose FVDSSE, the first fault-tolerant DSSE scheme that tolerates client-side operational faults and provides result verifiability against malicious servers. Moreover, it simultaneously ensures strong privacy by guaranteeing forward and backward privacy—two essential properties for any practical DSSE. To further optimize performance, we present FVDSSE-C, an enhanced variant that leverages caching techniques. Experimental evaluations on a real-world dataset show that FVDSSE-C achieves up to 130× improvement in search efficiency and 3× reduction in communication overhead compared to the state-of-the-art scheme (YCR22-C).

Multi-modal Federated Learning (MFL) is a distributed machine learning paradigm that enables multiple participants with multi-modal data to collaboratively train a global model for multi-modal tasks without sharing their local data. MFL typically deploys the trained global model as an Embedding-as-a-Service (EaaS), allowing participants to obtain embeddings for downstream tasks. However, it increases the risk of unauthorized copying and leakage of the model. Protecting the ownership of the MFL model while maintaining model performance is challenging. In this paper, we propose the first general model ownership protection framework for MFL, named MFL-Owner. MFL-Owner decouples the watermarking process from the model training process and addresses both ownership verification and traceability, effectively safeguarding the interests of the MFL collective. MFL-Owner leverages the concept of orthogonal transformations by incorporating a linear transformation matrix with orthogonal constraints into the model, achieving high-quality ownership verification and traceability with minimal impact on model performance. To enhance the practicality of the watermark and prevent conflicts among multiple clients during tracing, we propose a trigger dataset selection method based on out-of-distribution data combined with Gaussian noise perturbation. Our experiments on multiple datasets demonstrate that MFL-Owner is effective for model ownership verification and traceability for MFL.

The vast, complex, and dynamic nature of social message data has posed challenges to social event detection (SED). Despite considerable effort, these challenges persist, often resulting in inadequately expressive message representations (ineffective) and prolonged learning durations (inefficient). In response to the challenges, this work introduces an unsupervised framework, HyperSED (Hyperbolic SED). Specifically, the proposed framework first models social messages into semantic-based message anchors, and then leverages the structure of the anchor graph and the expressiveness of the hyperbolic space to acquire structure- and geometry-aware anchor representations. Finally, HyperSED builds the partitioning tree of the anchor message graph by incorporating differentiable structural information as the reflection of the detected events. Extensive experiments on public datasets demonstrate HyperSED's competitive performance, along with a substantial improvement in efficiency compared to the current state-of-the-art unsupervised paradigm. Statistically, HyperSED boosts incremental SED by an average of 2%, 2%, and 25% in NMI, AMI, and ARI, respectively; enhancing efficiency by up to 37.41 times and at least 12.10 times, illustrating the advancement of the proposed framework.

Website fingerprinting (WF) attacks on Tor networks can analyze traffic patterns to identify the websites Tor users are visiting, and thus pose a significant threat to user privacy. In a real-world environment, Tor users face diverse network conditions and can also employ WF defenses, raising new challenges to launch WF attacks. The state-of-the-art (SOTA) WF attacks either rely on a strong assumption that WF classifiers are trained and deployed under the same network condition, or suffer from significant performance degradation against WF defenses. In this paper, we propose Swallow, a transfer-robust WF attack that can quickly transfer to new network conditions while maintaining robustness against various WF defenses. Specifically, we propose a novel trace representation named Consistent Interaction Feature (CIF), which aligns traffic distributions across different network conditions to capture consistent features. Then we design three data augmentation algorithms to simulate potential variations under various network conditions. We extensively evaluate Swallow using ten datasets, including both self-collected and public datasets. The closed- and open-world evaluation results demonstrate that Swallow significantly outperforms the SOTA attacks. In particular, with only 5 labeled instances per website for model fine-tuning, Swallow achieves an average improvement in accuracy of 17.50% over the SOTA WF attacks.

The advancement of large language models (LLMs) has made generative AI services an indispensable component of modern web applications, offering powerful capabilities through API-based interactions. However, the black-box nature of these services, where users lack access to internal mechanisms such as training or fine-tuning processes, poses significant challenges for adversarial attack research. Traditional attack methods typically require access to model parameters or gradients, which is impractical in real-world scenarios. In this paper, we introduce ChainAttack, a black-box adversarial method that exploits LLMs' incontext learning by crafting Chain-of-Thought (CoT) adversarial prompts. This method manipulates intermediate reasoning steps to elicit harmful outputs without requiring access to model internals. Our evaluation across six benchmarks demonstrates that ChainAttack achieves a 34.4% success rate, particularly excelling in logic-intensive tasks such as mathematical problem solving. This work exposes critical vulnerabilities in CoT prompting and underscores the need for future research on building more robust and trustworthy generative AI systems.

Latent diffusion models have exhibited considerable potential in generative tasks. Watermarking is considered to be an alternative to safeguard the copyright of generative models and prevent their misuse. However, in the context of model distribution scenarios, the accessibility of models to large scale of model users brings new challenges to the security, efficiency and robustness of existing watermark solutions. To address these issues, we propose a secure and efficient watermarking solution. A new security mechanism is designed to prevent watermark leakage and watermark escape, which considers watermark randomness and watermark-model association as two constraints for mandatory watermark injection. To reduce the time cost of training the security module, watermark injection and the security mechanism are decoupled, ensuring that fine-tuning VAE only accomplishes the security mechanism without the burden of learning watermark patterns. A watermark distribution-based verification strategy is proposed to enhance the robustness against diverse attacks in the model distribution scenarios. Experimental results prove that our watermarking consistently outperforms existing six baselines on effectiveness and robustness against ten image processing attacks and adversarial attacks, while enhancing security in the distribution scenarios. The code is available at https://anonymous.4open.science/r/DistriMark-F11F/.

In wireless communication, data is typically encrypted before transmission to ensure confidentiality, which complicates the implementation of access control.Predicate encryption based (PE-based) access control enables fine-grained and secure control over encrypted data. The previous PE-based access control systems only guarantee the access of the authorized receivers but not control illegal senders, and have to execute re-authorization due to its static setting. In this paper, we propose a verifiable predicate-based access control encryption supporting dynamic revocation scheme (dvPACE), which is a dynamic access control mechanism on both senders and receivers. In contrast to existing access control, dvPACE controls not only "who can access" but also "who can send". It involves an additional sanitizer to handle the cipher data and embraces multi-verification against illegal entities. To achieve efficiency and scalability, dvPACE embeds inner-product predicate encryption and borrows the idea of identity-based revocation systems. dvPACE achieves about 19ms computational cost of data access, a comparable performance over conventional mechanisms with improvements of functionalities.

Nowadays, checkpoints have been proven to be an effective solution to ensure slashability in proof-of-stake (PoS) consensus, and Tas et al.'s cutting-edge solution in S&P 2023 is a typical example. Unfortunately, despite progress, hour-level transaction delays and annually around 10 K dollar checkpoint costs make existing related solutions still unacceptable in realworld PoS applications. In this paper, we propose SecPoS, a slashable PoS consensus with second-level transaction delays and one-time checkpoint costs. To achieve these design goals, we draw inspiration from Pixel+ signatures and chameleon hash functions to design a novel bilateral blockchain structure, achieving twoblock transaction finalization via only uploading the first block of our chain as checkpoints. Next, considering practical application requirements, we address a series of following challenges, such as bilateral immutability, blockchain forks, determination of the main chain, and malicious attacks from PoS members. In detail, we propose two constructions of SecPoS, i.e., SecPoS – A and SecPoS – B. SecPoS – A and SecPoS – B have a tradeoff between transaction delays and block numbers packed in an epoch. Compatible with most existing one-way blockchains, we implement and outsource a prototype SecPoS to facilitate research11https://github.com/Academic-Paper-Codes/SecPoS-Consensus, and prove the security of SecPoS. Experiments on this prototype show that SecPoS – A and SecPoS – B require around 5s and 100s transaction delays, respectively, and both require 2 dollars one-time checkpoint costs.

Visual-audio Deepfake has become increasingly prevalent in today's online environment. Passive detection methods, lacking preventive measures, struggle with detecting unknown forgery techniques, limiting their effectiveness. While proactive detection methods offer greater robustness, unimodal watermarking approaches remain vulnerable in visual-audio Deepfake scenarios, posing challenges to reliable forensics. To address these challenges, we propose a novel Separable Visual-Audio waterMark framework, called SepVAMark, for proactive Deepfake detection. SepVAMark incorporates a multi-layer perceptron-based mixer layer to fuse intra-modality and inter-modality features from both audio and visual data. We introduce the concept of separable visual-audio watermark, along with a bimodal robust extractor for traceability and two unimodal semi-robust extractors for Deepfake detection. This design ensures reliable copyright protection for source audio-video content while enabling authenticity verification for redistributed content. Experimental results on the FakeAVCeleb dataset demonstrate that SepVAMark effectively detects a wide range of advanced Deepfake manipulations, outperforming existing single-modal and multi-modal watermarking methods with superior robustness.

Artificial intelligence (AI) revolutionizes the productivity model and efficiency of the Industrial Internet of Things (IIoT). As a derivative of the AI era, AI-enabled IIoT drives frequent data access and intelligent industrial productivity. However, the rise of intelligence brings more sophisticated and hard-to-defend attacks against IIoT systems, such as deep identity forgery and malicious access, posing a major threat to intelligent development. Password-based Authenticated Key Agreement (AKA) is an effective cryptographic method for access security in IIoT, but current AKA schemes cannot address balancing between security, functionality and efficiency in the smart setting. To fill this gap, we propose a new password-based AKA scheme, where oblivious pseudorandom function, hash function and encryption are utilized to realize anonymous identity authentication. Considering malicious data access, we design a new token-tag mechanism with identity information to realize malicious identity tracing. In addition, our scheme supports a fast login function, helping the authorized party access data without repeating key agreements. Furthermore, formal security proofs and heuristic analyses demonstrate that our scheme is secure under multiple attacks. Finally, we compare the proposed scheme with the related schemes, and the results show that our scheme achieves the balance between safety, function and efficiency.

Blockchain-based covert communication (BCC) provides high reliability and anonymity by embedding secret data into blockchain transactions. However, existing BCC approaches still face three fundamental limitations: (i) data mining risk, since transactions containing the secret data are permanently recorded on-chain and may be detected perpetually; (ii) limited efficiency, as only small payloads (e.g., 256 bits) can be carried per transaction; and (iii) private key leakage, where receivers often need access to the sender’s private key and may incur private key exposure. To address these issues, we propose a novel covert communication model with transaction withdrawal (BCC-TW) and a multisig-based data embedding scheme (MUL-DE). BCC-TW prevents covert transactions from being confirmed by constructing higher-fee double-spend transactions, thereby ensuring that secret data only exists temporarily in the mempool. MUL-DE encodes data into redundant public keys of Bitcoin multisig addresses, thus enabling higher efficiency and avoiding private key exposure. We implement a prototype on Bitcoin testnet and evaluate its concealment and efficiency. Experimental results demonstrate that the proposed approach achieves strong indistinguishability against statistical and deep-learning-based detectors, improves communication efficiency up to 251 bits per public key, and significantly reduces cost compared with state-of-the-art baselines.

Graph neural networks (GNNs) with differential privacy (DP) offer a reliable solution for safeguarding sensitive information within graph data. Nonetheless, existing DP-based privacy-preserving GNN learning frameworks generally overlook the local topological heterogeneity of graph nodes and tailor the same privacy budget for all nodes, which may lead to either overprotection or underprotection of some nodes, potentially diminishing model utility or posing privacy leakage risks. To address this issue, we propose a Topology-aware Differential Privacy Graph Neural Network learning framework, termed TDP-GNN, which can achieve personalized privacy protection for each node with improved privacy-utility guarantees. Specifically, TDP-GNN first identifies the topological importance of each node via an adjacency information entropy method. Then, the personalized topology-aware privacy budget is designed to quantify the privacy sensitivity of each node and adaptively allocate the privacy protection strength. Besides, a weighted neighborhood aggregation mechanism is proposed during the message-passing process of GNN training, which can eliminate the impact of the introduced differentiated DP noise on the utility of the GNN model. Since TDP-GNN is based on node-level local DP, it can be seamlessly integrated into any GNN architecture in a plug-and-play manner while ensuring formal privacy guarantees. Theoretical analysis indicates that TDP-GNN achieves ε-differential privacy over the entire graph nodes while providing personalized privacy protection. Extensive experiments demonstrate that TDP-GNN consistently yields better utilities when applied to various GNN architectures (e.g., GCN and GraphSAGE) across a diverse set of benchmarks.

Clustering is pivotal in deciphering cellular heterogeneity in single-cell RNA sequencing (scRNA-seq) data. However, it suffers from several challenges in handling the high dimensionality and complexity of scRNA-seq data. Especially when employing graph neural networks (GNNs) for cell clustering, the dependencies between cells expand exponentially with the number of layers. This results in high computational complexity, negatively impacting the model's training efficiency. To address these challenges, we propose a novel approach, called decoupled GNNs, based on multi-view contrastive learning (scDeGNN), for scRNA-seq data clustering. Firstly, this method constructs two adjacency matrices to generate distinct views, and trains them using decoupled GNNs to derive the initial cell feature representations. These representations are then refined through a multilayer perceptron and a contrastive learning layer, ensuring the consistency and discriminability of the learned features. Finally, the learned representations are fused and applied to the cell clustering task. Extensive experimental results on nine real scRNA-seq datasets from various organisms and tissues show that the proposed scDeGNN method significantly outperforms other state-of-the-art scRNA-seq data clustering algorithms across multiple evaluation metrics.

Blockchain-based decentralized identity (DID) typically employs identity aggregation techniques to support efficient and trustworthy identity authentication in order to meet the requirements of the high volume of service requests in Internet of Things (IoT). Due to the lack of effective mechanisms for heterogeneous DID (H-DID) aggregation, a complete aggregated identity authentication often requires multiple rounds of signature verification for different identity attributes. However, this setting brings trust and privacy issues, and one notable threat is the potential disclosure of secret identity information through the linkage of heterogeneous identity attributes when enormous IoT devices/accesses are involved. In this article, we focus on trustworthy authentication of DID and propose a novel anonymous verifiable credential-based aggregation for h-DID (AVCA-hDID). Our AVCA-hDID model supports anonymous ownership verification of DIDs through label randomization, thereby effectively safeguarding identity privacy in IoT. AVCA-hDID involves identifier aggregation and attribute aggregation for H-DIDs, ensuring both authentication efficiency and balancing trustworthiness and adoptability. We analyze the security and unlinkablility of our proposed model and further experiment evaluation demonstrates the efficiency and effectiveness of AVCA-hDID.

Point multiplication is the core operation in elliptic curve cryptography. Koblitz curves are a special class of curves that can utilize the Frobenius mapping to accelerate the implementation of point multiplication operations. For point multiplication on Koblitz curves, this paper first proposes an optimized tNAF scalar conversion algorithm along with its corresponding hardware architecture. Additionally, for the computation of point multiplication, this paper proposes two optimal computational architectures: an area-efficient architecture and a low-latency architecture, both of which achieve the highest pipeline efficiency. The area-efficient architecture adopts a compact four-stage pipeline with a single multiplier, ensuring high circuit area utilization efficiency while achieving relatively low computation latency. The low-latency architecture implements two-stage and three-stage pipeline designs respectively in different binary fields, using two multipliers to reduce the clock cycles for point addition and further decrease the computation latency. The proposed architectures were implemented on Virtex-7 FPGA. For the GF(2163), GF(2283), and GF(2571) fields, the latency for the area-efficient architecture are 1.683μs, 3.455μs and 7.511μs, with slices usage of 3631, 7867 and 20612, and the point multiplication latency for the low-latency architecture are 1.347μs, 3.279μs and 7.071μs, with slices usage of 6026, 14246 and 38515. A comparison with state-of-the-art designs shows that the proposed point multiplication architectures offer significant advantages in terms of performance. In the GF(2163) field, the computation latency of the area-efficient architecture and the low-latency architecture is reduced by at least 21.158% and 43.952%, respectively. And in the GF(2283) field, the reduction in latency is 38.985% and 42.459%, while in the GF(2571) field, the reduction in latency is 58.111% and 59.720%.

The Internet of Things (IoT) system gathers data through diverse smart devices and sensors to make thorough decisions tailored to specific needs. Yet, in intricate IoT setups, privacy infringement occurs through various means like data collection, initial data handling, and data sharing. Therefore, the concealment of data during transmission should receive sufficient attention. The communication approach that merges blockchain technology with covert communication has shown progress in addressing the aforementioned issues. However, this integration has also led to challenges, such as low-data embedding rates and distinctive features in blockchain transactions containing covert data. To seek a solution with high-embedding rates that do not make generated transactions stand out distinctly, this article analyzes the Ethereum transaction field formats, identifies the input data field with high concealment and large capacity as the embedding target, then proposes a data covert transmission scheme based on hybrid embedding in contract fields. This scheme utilizes LSB steganography to embed high-capacity covert data in images, and embeds the URL of the image into the input data field of the Ethereum smart contract transaction, thereby increasing the embedding rates. Subsequently, to further enhance the concealment of this scheme, a data embedding method based on contract relationships is proposed. Through this technique, for the first time, covert data transmission is achieved solely through the invocation relationships of smart contracts within the blockchain covert communication environment, instead of directly embedding covert data into transactions. This method results in transactions that are theoretically indistinguishable from regular transactions, greatly enhancing the security of the scheme. Finally, an evaluation of undetectability, embedding rate, and scalability was conducted for the proposed schemes, concluding that the schemes presented in this article have significant advantages in all three areas.

Hierarchical Federated Learning (HFL) has emerged as a popular federated learning method by introducing additional aggregation levels using intermediate edge servers. The performance of HFL approaches is contingent upon the aggregation frequency and the number of intermediate aggregation rounds. Existing approaches mainly focus on optimizing the aggregation frequency only, neglecting the impact of intermediate aggregation rounds on training performance. On the other hand, these methods also fail to consider the multidimensional effects of aggregation frequency, consequently focusing only on the performance accuracy while overlooking the detrimental effects on both the communication costs and training latency. This paper introduces HFL-PBRL, a novel HFL framework that employs a bi-level reinforcement learning (RL)-based algorithm to jointly optimize aggregation frequencies and rounds across edge servers. This algorithm is accompanied by a Pareto-efficient multi-objective optimization approach to strike an optimal trade-off among model accuracy, communication cost and convergence time. The varied aggregation frequencies and rounds might introduce inconsistencies; therefore, we employ a hierarchical pullback mechanism that iteratively pulls the client models toward a synchronized anchor model, ensuring effective divergence control. Furthermore, we devise a harmonic weight assignment strategy that dynamically adjusts the aggregation weights of each model based on their current, historical, and anticipated divergence, addressing the model fluctuations and asynchrony. Extensive evaluations demonstrate that HFL-PBRL consistently achieves high model accuracy and faster convergence with minimal communication costs compared to baselines and SOTA.

Classical cluster-based side-channel analysis (SCA) uses clustering algorithms to analyze power traces and often, principal component analysis to reduce the dimension of data, resulting in that clustering may not deal well with high-dimensional traces, such as cryptographic algorithm implementations with countermeasures. In this article, we propose an intelligent framework for cluster-based SCA, which includes three steps of clustering, classification and correction, for processing large high-dimensional data. By combining unsupervised clustering and supervised deep learning techniques, the framework succeeds in mining the data for additional in-depth information. In addition, unlike traditional cluster-based SCA, our approach focuses on deep learning and deliberately avoids over-reliance on cluster labels during classification. And metrics for correction are adopted to achieve a high level of reliability in key recovery. Experiments on the RSA smart card based on Montgomery ladder implementation and FPGA-based ECC with random delay demonstrate that our framework can significantly improve the success rate with strong robustness.

The rapid development of the Internet of Things has increased the importance of IoT data privacy. Traditional encryption and access control mechanisms are insufficient for ensuring privacy. Blockchain-based covert communication offers enhanced concealment, anonymity, and immutability for secure information exchange over open networks. However, existing blockchain-based schemes face limitations in point-to-point communication and low screening efficiency and concealment, as well as challenges when extended to group scenarios, such as the existence of leakers. To address these issues, we propose a Blockchain-based Group Covert Communication (BGCC) scheme. BGCC leverages broadcast encryption to revoke leakers and introduces an efficient covert filtering mechanism based on the decisional ℓ-BDHE assumption. We prove its concealment through security reduction, statistical tests, and machine learning test. Experimental results demonstrate that BGCC outperforms existing schemes.

The rapid development of Internet of Things (IoT) technology has transformed people’s way of life and has a profound impact on both production and daily activities. However, with the rapid advancement of IoT technology, the security of IoT devices has become an unavoidable issue in both research and applications. Although some efforts have been made to detect or mitigate IoT security vulnerabilities, they often struggle to adapt to the complexity of IoT environments, especially when dealing with dynamic security scenarios. How to automatically, efficiently, and accurately understand these vulnerabilities remains a challenge. To address this, we propose an IoT security assistant driven by a Large Language Model (LLM), which, through the ICoT process, enhances the LLM’s understanding of IoT security vulnerabilities and related threats. The ICoT method we propose aims to enable the LLM to understand security issues by breaking down the various dimensions of security vulnerabilities and generating responses tailored to the user’s specific needs and expertise level. By incorporating ICoT, LLM can gradually analyze and reason through complex security scenarios, resulting in more accurate, in-depth, and personalized security recommendations and solutions. Experimental results show that, compared to methods relying solely on LLMs, our proposed LLM-driven IoT security assistant significantly improves the understanding of IoT security issues and provides personalized solutions based on user identity through the ICoT approach. From the evaluator’s perspective, it performs better across five dimensions.

Based on emerging artificial intelligence (AI) tasks, cloud-edge–terminal architecture can provide powerful computing, intelligent interconnection, and real-time response, which can also be regarded as AI-driven network. Unfortunately, multiple network layers in the AI-driven network usually face various types of network threats, such as malicious network reconnaissance, side-channel attacks, and distributed denial of service (DDoS). Traditional security solutions respond to network threats after the occurrence of attacks. To solve this problem, the concept of moving target defense (MTD) has been proposed as a proactive defense mechanism that aims to defend against cyber attacks before they occur. In this article, we first provide a thorough analysis of the threats in the cloud-edge–terminal network. Then, we conduct a comprehensive survey to discuss the concept, design principles, and main classifications of MTD. Next, we further introduce the development potential in terms of AI-powered MTD on each network layer. Meanwhile, we also explore how MTD improves the security of AI algorithms. Lastly, we describe the existing challenges and research directions of MTD. The aim of this article is to provide an in-depth understanding for the readers on how to realize the integration between MTD and AI-driven network.

With the deepening militarization of global cyberspace, cyber threats have evolved into advanced persistent threats (APTs), characterized by high targeting, persistence, and destructiveness, rendering traditional perimeter-based defenses ineffective. In response, researchers have proposed the zero-trust architecture, which enforces strict identity verification for all access requests, whether external or internal, to reduce the attack surface and mitigate APTs lateral movement. However, zero-trust remains largely a conceptual framework rather than a standardized technical solution, with existing approaches primarily integrating conventional security mechanisms under zero-trust principles without systematically deconstructing threats from an APT countermeasure perspective. Consequently, these methods struggle to identify APTs at the tactical and technical level or accurately assess and mitigate APT risks. To address the above problems, this article proposes a access control method within zero-trust network for APT mitigation. First, this article identifies APT tactics, techniques, and procedure that threaten zero-trust by leveraging MITRE ATT&CK mitigations and zero trust maturity model. Next, this article designs an attack detection algorithm using Sigma rules, correlating historical entity behavior with security alerts to uncover APT indicators. Finally, this article establishes a risk assessment framework for network entities based on APT behavioral patterns, devises a trust computation model tailored to APTs, and implements dynamic access control policies weighted by entity trust levels. The experimental results demonstrate the method’s feasibility and effectiveness, achieving 93.1% APT attack detection rate, offering a new approach for mitigating APT attacks.

Personalized federated recommendation systems can not only extract common prior knowledge from extensive decentralized data but also provide personalized models for different users to achieve independent and customized services. Incorporating user relationship graphs to enhance personalized modeling is highly promising in federated recommendation. However, it is challenging to construct such graphs and further capture personalized user information while guaranteeing multi-level (i.e., data-level and edge-level) privacy in reality. To this end, in this paper, we propose P 2 FedRec, a relationship-aware P rivacy-preserving and P ersonalized Fed erated Rec ommendation scheme, which can achieve multi-level privacy protection with personalized modeling guarantees. Specifically, we first develop a user-server collaborative mechanism for relationship graph generation and user-specific preferences capture in a privacy-preserving manner. Then, we design an embedding-shared local graph construction module and a noisy global graph-guided aggregation module to safeguard the data-level and edge-level privacy, respectively. Moreover, we introduce a personalized model training module that enables users to learn tailored local models. Theoretical analysis demonstrates that P 2 FedRec achieves both data-level and edge-level privacy preservation on the user and server sides. Extensive experiments conducted on five real-world datasets highlight the outstanding performance of P 2 FedRec.

Recent developments in the field of Dynamic Searchable Symmetric Encryption (DSSE) with forward and backward privacy have attracted much attention from both research and industrial communities. However, most DSSE schemes with forward and backward privacy schemes only support single keyword queries, which impedes its prevalence in practice. Although some forward and backward private DSSE schemes with expressive queries (e.g., conjunctive queries) have been introduced, their backward privacy either essentially corresponds to single keyword queries or forward privacy is not comprehensive. In addition, the deletion of many DSSE schemes is achieved by addition paired with a deletion mark (i.e., lazy deletion). To address these problems, we present two novel DSSE schemes with conjunctive queries (termed SDSSE-CQ and SDSSE-CQ-S), which achieve both forward and backward privacy. To analyze their security, we present two new levels of backward privacy (named Type-O and Type-O-, more and more secure), which give a more comprehensive understanding of the leakages of conjunctive queries in the OXT framework. Eventually, the security analysis and experimental evaluations show that the proposed schemes achieve better security with reasonable computation and communication increase.

Depending on large-scale devices, the Internet of Things (IoT) provides massive data support for resource sharing and intelligent decision, but privacy risks also increase. As a popular distributed learning framework, Federated Learning (FL) is widely used because it does not need to share raw data while only parameters to collaboratively train models. However, Federated Learning is not spared by some emerging attacks, e.g., membership inference attack. Therefore, for IoT devices with limited resources, it is challenging to design a defense scheme against the membership inference attack ensuring high model utility, strong membership privacy and acceptable time efficiency. In this paper, we propose MemDefense, a lightweight defense mechanism to prevent membership inference attack from local models and global models in IoT-based FL, while maintaining high model utility. MemDefense adds crafted pruning perturbations to local models at each round of FL by deploying two key components, i.e., parameter filter and noise generator. Specifically, the parameter filter selects the apposite model parameters which have little impact on the model test accuracy and contribute more to member inference attacks. Then, the noise generator is used to find the pruning noise that can reduce the attack accuracy while keeping high model accuracy, protecting each participant's membership privacy. We comprehensively evaluate MemDefense with different deep learning models and multiple benchmark datasets. The experimental results show that lowcost MemDefense drastically reduces the attack accuracy within limited drop of classification accuracy, meeting the requirements for model utility, membership privacy and time efficiency.

With the rapid development of cloud computing, online health monitoring systems are becoming increasingly prevalent. To protect medical data privacy while supporting search operations, Dynamic Searchable Symmetric Encryption (DSSE) technology has been widely used in health monitoring systems. For better monitoring of patient status, keyword range query is also a necessary requirement for the DSSE scheme. Furthermore, in the multi-user setting, user revocation usually leads the owner to download and re-encrypt all indexes, resulting in significant computational overhead. In this paper, we propose a lightweight revocable DSSE scheme with range query support. First, we propose a novel and privacy-preserving range query algorithm that defends plaintext inference attacks. Second, we design a singly linked list structure based on delegatable pseudorandom functions and key-updatable pseudorandom functions, which support lightweight user revocation. Rigorous security analysis proves the security of our proposed range query scheme and demonstrates that our scheme can achieve forward and backward privacy. Experimental evaluations show that our scheme is highly efficient.

Cross-chain technology facilitates the interoperability among isolated blockchains, where users can transfer and exchange coins. While the heterogeneity between Turing-complete (TC) blockchains like Ethereum and non-Turing-complete (NTC) blockchains like Bitcoin presents a significant challenge for cross-chain transactions. Payment Channel Hubs (PCHs) offer a promising solution for enabling TC-NTC cross-chain payments with high throughput and low confirmation delays. However, existing schemes still face two key challenges: (i) significant computation and communication overhead for variable-amount payment, and (ii) limited unlinkability, i.e., vulnerable to the abort attack. This paper proposes EC2P, the first TC-NTC cross-chain PCH that achieves variable-amount payment unlinkability while resisting the abort attack and minimizing reliance on non-interactive zero-knowledge (NIZK) proofs. EC2P introduces two protocols: the NTC-to-TC and TC-to-NTC payment protocols. The NTC-to-TC payment protocol replaces the traditional puzzle-promise and puzzle-solve paradigm with a semi-blind approach, where only one side is blinded and the blinded side’s interactions are eliminated. This achieves unlinkability and resists the abort attack without NIZK. The TC-to-NTC payment protocol enhances the paradigm by utilizing Turing-complete functionality to constrain the inability to carry out an abort attack. Through rigorous security analysis, we show that EC2P is secure and variable-amount payment unlinkable while resisting the abort attack. We implement EC2P on Ethereum and Bitcoin test networks. Our evaluation demonstrates that EC2P outperforms both in terms of communication and computation overhead and reduces communication costs by 3 orders of magnitude compared to existing variable-amount methods.

Timing analysis presents a significant threat to cryptographic modules. However, traditional timing leakage analysis has notable limitations, especially when precise execution times cannot be obtained. In this article, we propose a novel timing leakage analysis method that leverages horizontal leakage in the power/electromagnetic channel by detecting the trace length of encryption processes under varying inputs. To demonstrate the effectiveness of our approach, we conducted systematic experimental evaluations across a range of cryptographic devices. In comparison to timing leakage analysis based on plaintext-ciphertext correlation, our method offers higher accuracy at lower testing costs and exhibits improved resistance to vertical noise.

The use of a single image restoration framework to achieve multi-task image restoration has garnered significant attention from researchers. However, several practical challenges remain, including meeting the specific and simultaneous demands of different tasks, balancing relationships between tasks, and effectively utilizing task correlations in model design. To address these challenges, this paper explores a multi-expert adaptive selection mechanism. We begin by designing a feature representation method that accounts for both the pixel channel level and the global level, encompassing low-frequency and high-frequency components of the image. Based on this method, we construct a multi-expert selection and ensemble scheme. This scheme adaptively selects the most suitable expert from the expert library according to the content of the input image and the prompts of the current task. It not only meets the individualized needs of different tasks but also achieves balance and optimization across tasks. By sharing experts, our design promotes interconnections between different tasks, thereby enhancing overall performance and resource utilization. Additionally, the multi-expert mechanism effectively eliminates irrelevant experts, reducing interference from them and further improving the effectiveness and accuracy of image restoration. Experimental results demonstrate that our proposed method is both effective and superior to existing approaches, highlighting its potential for practical applications in multi-task image restoration. The source code of the proposed method is available athttps://github.com/zhoushen1/MEASNet.

Ensuring scalability in cryptocurrency systems is significant in guaranteeing real-world utility along with the remarkable increment of cryptographic currency. As an alternative in solving scalability issue, payment channel allows users to deliver extensive offline transactions without uploading massive transaction details to the blockchain, such that increasing efficiency can be achieved. However, the implementation of payment channel still encounters privacy concerns when considering the publicly available transaction amounts and the potentials in mining associations between transaction parties. In this paper, we propose a novel payment channel scheme, entitledCommitment-basedAnonymousPayment ChannEl (CAPE), to facilitate unlimited off-chain bidirectional payments while guaranteeing participants’ privacy. The proposed scheme adopts zero-knowledge proof (zk-SNARKs) and verifiable timed (VTD) commitments to ensure the anonymity of the relationship between on-chain and off-chain transactions, privacy of transaction amounts, and security of balances. We comprehensively formalize security definitions and present rigorous proofs for each security attribute. Experiment results further demonstrate the practical viability of CAPE.

Multi-Party Computation (MPC), as a distributed computing paradigm, is considered to be a potential solution for providing privacy-preserving for applications following the client-server model. However, traditional MPC solutions cannot satisfy the publicly verifiable requirement of the client-server model. In this paper, we propose a blockchain-based verifiable MPC solution using Pedersen's threshold secret sharing and Lifted ElGamal encryption. We first build a data distribution method using Pedersen's threshold secret sharing and symmetric encryption to protect the privacy of inputs while ensuring robustness. Then, we propose a result processing algorithm using Lifted ElGamal encryption to safeguard the privacy of the outputs. Finally, we employ non-interactive zero-knowledge proof and Pedersen commitment to publicly verify the correctness of the encrypted outputs in the smart contract, enabling the detection of malicious parties. Theoretical analysis indicates that the proposed method can publicly verify the correctness of outputs without revealing plain-text inputs and outputs, which satisfy the privacy-preserving requirements of the client-server model. Experimental evaluations have demonstrated that our proposed approach is efficient regarding computation overhead, communication overhead, and response time in the output verification phase while achieving stronger privacy and robustness.

Although consortium blockchain has an identification mechanism, the captured internal clients are potentially threatening internal blockchain nodes. Internal Distributed Denial-of-Service (DDoS) attacks threaten the specific nodes in consortium blockchain, e.g., the executor, consensus, and committer nodes. Typical attack methods may include SYN Flooding and ACK Flooding and deny normal transaction service by sending many invalid transactions and blocks. In this work, we have proposed an organization collaboration-based DDoS defense approach and a Deep Q-learning (DQN)-based Moving Target Defense (MTD) for changing attack surface of victims in consortium blockchain. On one hand, contracts are used to synchronize attack information obtained from organizations, e.g., bots’ IP addresses and public keys. On the other hand, we have developed a DQN-based MTD defense mechanism for organizations to change the attack surface of victims in order to mitigate the malicious traffic, in the case of missing detections of bots. Our approach applies a multi-stage game to reflect interactions between attackers and defenders. The evaluation results have demonstrated that our approach could effectively mitigate DDoS attacks in consortium blockchain.

As blockchain technology matures and its adoption grows across multiple industries, there is a growing need to make the data stored on blockchains adaptable to prevent misuse. However, such modifications can lead to inconsistency when interacting with other blockchains, necessitating the preservation of dynamic data consistency during these cross-chain interactions. While ensuring consistency for static data is relatively straightforward, doing so for dynamic data with efficiency remains a significant challenge. In response, we propose an efficient dynamic cross-chain data consistency auditing model (EDCA), which artfully integrates an advanced gamma multi-signature approach (AGMS) with the designed dynamic Merkle hash tree (D-MHT) to facilitate effective auditing of the consistency for dynamic data in cross-chain interaction. EDCA can produce relatively small auditor states while maintaining the storage proof. Moreover, EDCA is proven to satisfy strong security and privacy guarantees, tag unforgeability, and proof unforgeability. Experimental evaluations confirm that EDCA has high computational and communicational efficiency and can retain a small and relatively constant auditing overhead.

Navigation services enable users to find the shortest path from a starting point$S$to a destination$D$, reducing time, gas, and traffic congestion. Still, navigation users risk the exposure of their sensitive location data. Our motivation arises from how users can accurately, securely, and efficiently navigate from$S$to$D$while passing through$k$unordered stops, i.e., midway locations with a non-fixed visiting order. In this work, we formally define Semi-Constrained Navigation (SCN) and present a novel scheme Hermes to achieve accurate, secure, and efficient SCN. Specifically, we propose a divide-and-conquer approach to strike a good balance between accuracy and efficiency. It recursively depth-first-searches the whole area (a navigation tree) and invokes five carefully-crafted strategies stop-by-stop to compute three subpaths in three sequential subareas. We construct a path-distance oracle to encrypt the road graph and securely implement the strategies by using homomorphic encryption and garble circuits. We formally prove the security in the random oracle model and analyze the search complexity to be less than$O(k^{2})$. We experiment over a real-world city map and compare with six baselines. Results show that path search with$k=4$among$N=1000$intersections requires 5.58 seconds with a 3.2% distance deviation rate and an 82.5% path similarity.

This paper seeks to enhance the performance of large-scale leader-based Byzantine Fault Tolerant (BFT) systems by proposing a novel Group BFT scheme. The scheme utilizes a two-round message transmission process to distribute the load from a single leader across multiple replicas by dividing the entire consensus network into groups, each with an equal number of replicas. Each group has a leader to process the group's voting messages into a single aggregated voting message during the first round, which is then transmitted to the consensus leader in the second round (similar process for proposing). We establish a formal system framework for Group BFT protocols with a versatile set of base components and explicit definitions, addressing the challenges inherent in designing such a system. We further design and implement two highly efficient Group BFT protocols: one that supports inter-group member exchange and the other one that does not. We theoretically prove the safety, liveness, and responsiveness of the Group BFT protocols. We conduct a formal analysis of Group BFTs' tolerance and complexity. Experimental results show that the two Group BFT protocols significantly alleviate the processing bottlenecks of the leader and highly improve throughput in large-scale systems.

With the development of information and communication technology, the Internet of Things (IoT) has gained significant popularity across various applications. As the number of devices surges and data generation accelerates, robust data security and accurate data retrieval have become increasingly important. Fuzzy keyword search provides an elegant way to allow retrieval over encrypted data. Privacy and accuracy are two important factors when applying fuzzy keyword search into cloud storage systems. State-of-the-art mechanisms cannot effectively balance privacy and accuracy, and they even compromise the access pattern. In this paper, we propose SeaPA, a fuzzy keyword search scheme with strong privacy and high accuracy. SeaPA is built on top of two non-colluding servers and integrated with secure multi-party computation. To construct SeaPA, we introduce a top-k document retrieval algorithm that conceals the similarity of search results from identical queries, preventing access pattern leakage. We implement a prototype system and conduct extensive experiments on the 20NewsGroups dataset. The results show that SeaPA achieves higher accuracy, with over$16\times$speedups in index encryption efficiency and over$9.3\times$speedups in search efficiency, compared to previous schemes.

Data integrity auditing technology serves as an essential tool to ensure the data's integrity with the popularity of remote storage. However, existing data integrity auditing models are unsuitable for a large number of files with interrelationships and heavily depend on a centralized Third-Party Auditor (TPA). To address these issues, in this paper we propose a blockchain-assisted searchable integrity auditing scheme for large-scale similarity data. To broaden the scope of the auditing model and enhance its ability to handle interconnected files, we utilize the keyword to design a search index and a trapdoor to achieve authenticator searchability for the interconnected files. The integrity of the searching result from the cloud side can be guaranteed at the same time. To reduce reliance on centralized TPA and enhance the credibility and transparency of auditing, we integrate blockchain technology along with smart contracts to replace TPA and achieve multitask auditing. We adopt a certificateless cryptosystem to generate the authenticator, while considering the cost reduction. Moreover, an arbitrator is proposed to achieve fairness judge. Theoretical and security analysis demonstrate that the proposed scheme is efficient and secure, making it a promising solution for data auditing in a wide range of applications.

As decentralized storage becomes more prevalent, ensuring data integrity within these systems has gained increasing importance. However, the introduction of a centralized and trustedCloud Combiner(CO) to manage auditing across distributedCloud Servers(CSs) presents several challenges, which not only increases communication costs with independent CSs but also diminishes the credibility of the auditing results. Additionally, traditional approaches often require either certificate and key management or the establishment of secure transmission channels, which incur substantial overhead. Furthermore, the computational cost for index generation to support searchable auditing is often high. To address these challenges, we propose a collaborative and searchable integrity auditing scheme for multi-replica data that eliminates the need for a CO. Specifically, we design a certificate-based authenticator for multi-copy data blocks, which simplifies certificate and key management while removing the need for secure channels. To enable efficient searchable auditing, we introduce a novel index tag that matches authenticators, thereby reducing the computational overhead. Moreover, we leverage blockchain technology to enhance the credibility of the auditing process and ensure the integrity of the search results. Both security and performance analyses demonstrate that the proposed scheme is secure and efficient.

Blockchain technology, known for its decentralization and immutability, has been widely applied across various domains. However, this immutability reveals limitations in adapting to rapidly changing legal environments and preventing malicious misuse. To introduce a degree of flexibility, various transaction-level redactable blockchain solutions have been proposed. Yet, current schemes grant modifiers redaction privileges by providing access to the trapdoor, potentially posing risks of malicious dissemination and abuse of the trapdoor. In this paper, we first propose an RSA-based threshold chameleon hash (TCH) construction, allowing the distribution of the trapdoor among a group of authorities. Building on TCH, we develop a threshold policy-based chameleon hash (TPCH). Compared to the Policy-Based Chameleon Hash (PCH) proposed by Derler at NDSS'19, our TPCH supports authorization without exposing the trapdoor. Furthermore, leveraging TPCH, we introduce a novel transaction-level redactable blockchain (TPRB). TPRB supports decentralized authorization without trapdoor exposure and fine-grained rewriting control. Finally, through implementation and evaluation, we demonstrate the practicality and efficiency of our TCH and TPCH schemes.

Federated Learning (FL) realizes distributed machine learning training via sharing model updates rather than raw data, thus ensuring data privacy. However, an attacker may infer the client's local original data from the model parameter so that original data leakage can be caused. While Differential Privacy (DP) is designed to address data leakage issues in FL, injecting noises during training reduces model accuracy. To minimize the negative impact caused by noises on model accuracy while considering privacy protections, in this article we propose an adaptive FL model, entitledRDP-basedAdaptiveFederatedLearning inShuffle model (RAFLS). To ensure the dataset privacy of clients, we inject adaptive noises into the client's local model by leveraging the adaptive layer-wise adaptive sensitivity of the local model. Our approach shuffles all local model parameters in order to address privacy explosion concerns caused by high-dimensional aggregation and multiple iterations. We further propose a fine-grained model weight aggregation scheme to aggregate all local models and obtain a global model. Our experiment evaluations demonstrate the proposed RAFLS has a better performance than the state-of-the-art methods in reducing noise's impact on model accuracy while protecting data, i.e., showing that the accuracy of RAFLS increases by 1.54% than that of the baseline scheme when$\epsilon = 2.0$and FashionMNIST under IID setting.

With the rapid evolution of Web3.0, cryptocurrency has become a cornerstone of decentralized finance. While these digital assets enable efficient and borderless financial transactions, their pseudonymous nature has also attracted malicious activities such as money laundering, fraud, and other financial crimes. Effective detection of malicious accounts is crucial to maintaining the security and integrity of the Web 3.0 ecosystem. Existing malicious account detection methods rely on large amounts of labeled data and suffer from low generalization. Label-efficient and generalizable malicious account detection remains a challenging task. In this paper, we propose ShadowEyes, a framework for detecting malicious accounts by leveraging interaction feature learning with only a small labeled dataset. Specifically, We first propose a generalized account representation named TxGraph, which captures the universal interaction features of Ethereum and Bitcoin. Then we carefully design an account representation augmentation method tailored to simulate the evolution of malicious accounts to generate positive pairs. We conduct extensive experiments using public datasets to evaluate the performance of ShadowEyes. The results demonstrate that it outperforms state-of-the-art (SOTA) methods in four typical scenarios. Specifically, in the scenario of acrossplatform malicious account detection, ShadowEyes maintains an F1 score of around 90%, which is 10% higher than the SOTA method. In the zero-shot learning scenario, it can achieve an F1 score of 79.56% for detecting gambling accounts, surpassing the SOTA method by 10.44%.

Ethereum serves as the cornerstone for value transfer in Web 3.0, providing a decentralized and efficient trust mechanism for global connectivity. However, the anonymity of Ethereum undermines market regulatory capabilities, leading to frequent malicious behaviors such as Ponzi Scheme, Money Laundering, and Phishing. Therefore, in the face of the diverse and continuously emerging malicious behaviors, implementing fine-grained detection is crucial for maintaining the prosperous development of the blockchain ecosystem. In this paper, we propose FiMAD, a fine-grained and class-incremental malicious account detection framework based on dynamic graph learning. Specifically, we first propose a general graph structure calledDynamic Account Relation Graph (DARG), which dynamically models Ethereum accounts from a continuous-time perspective. Then, we design a cascade graph feature extraction method to capture deep temporal evolution patterns and neighbor interaction features in DARG. Next, we construct a pre-training universal encoder to transform account features into high-dimensional embeddings, followed by fine-tuning the model classifier with a few labeled samples, enabling accurate fine-grained detection and rapid updates for incremental classes. We conduct extensive experiments using real Ethereum data. The results demonstrate that FiMAD outperforms state-of-the-art (SOTA) methods in fine-grained detection across five typical scenarios: class-incremental, full data, new malicious accounts, imbalanced data, and binary classification. In the class-incremental scenario, FiMAD improves the Macro-F1 by up to 26.4% compared to SOTA methods.

Ring Confidential Transactions (RingCT) is a classic cryptographic protocol for anonymous transactions on blockchains, currently used in the popular anonymous cryptocurrency Monero. The proof size of RingCT transactions is linearly related to the ring size, which limits the use of larger ring sizes due to the significant communication overhead it incurs. However, reducing the ring size also leads to decreased anonymity. Therefore, in recent years, many studies have focused on optimizing the proof sizes for RingCT, with the latest known solutions reducing the proof size to be logarithmic with the ring size. In this paper, we propose a new compact RingCT protocol (CRCT) for smaller proof sizes. To this end, we first design three extended schemes of the Sum Argument (CRYPTO’21), which are used to generate logarithmic-sized proofs for three distinct zero-knowledge arguments, respectively. We then introduce a new zero-knowledge proof scheme called the Difference Argument. It is used to prove that one has the knowledge of two secret values, with their difference being public. Based on these schemes, we construct our CRCT protocol, whose proof size is independent of the ring size and logarithmic with the number of source accounts. We provide concrete constructions and security proofs for the proposed cryptographic schemes. The experimental results demonstrate that CRCT exhibits significant advantages in computational efficiency and proof size over existing solutions when dealing with large ring sizes and moderate numbers of source accounts.

Vertical Federated Learning(VFL) has gained widespread attention due to its ability of enabling collaborative model training among participants with diverse data features.Differential Privacy(DP) offers provable privacy guarantees for VFL, but existing DP-based methods typically compromise accuracy for privacy protection. To address this issue, we propose a novel scheme, called Adaptive Differential Privacy-based Vertical Federated Learning (Ada-VFed), that enhances privacy of data features and labels by adding Gaussian noise separately to the transmitted intermediate results and gradients. To improve model accuracy, we incorporate adaptive constraints through regularization terms in the objective function to mitigate the impact of clipping operations. In addition, we propose a dynamic noise injection mechanism that adjusts noise according to the importance of each dimension, thereby balancing privacy protection and model accuracy. Our theoretical analysis provides privacy guarantees and convergence insights. Extensive experiments demonstrated that our scheme significantly outperforms state-of-the-art DP-based VFL methods in terms of accuracy. Even with a small privacy budget (e.g.,ϵ = 0.5), our method improves the accuracy on MNIST, FashionMNIST, and CIFAR-10 by 13.01%, 10.08%, and 3.40%, respectively, compared to traditional DP-based VFL methods.

Federated Learning (FL) is an alternative approach that facilitates training machine learning models on distributed users’ data while preserving privacy. However, clients have different local model structures and most local data are non-independent and identically distributed, so that FL encounters heterogeneity and catastrophic forgetting issues when clients continuously accumulate new knowledge. In this work, we propose a scheme called MUFTI (Multi-Domain Distillation-based Heterogeneous Federated ConTInuous Learning). On one hand, we have extended domain adaptation to FL via extracting features to obtain feature representations on unlabeled public datasets for collaborative training, narrowing the distance between feature outputs of different models under the same sample. On the other hand, we propose a combining knowledge distillation method to solve the catastrophic forgetting issue. Within a single task, dual-domain distillation is used to avoid data forgetting between different domains; for cross task learning in task flow, the logits output of the previous model is used as the teacher to avoid forgetting old tasks. The experiment results showed that MUFTI had a better performance in accuracy and robustness comparing to state-of-the-art methods. The evaluation also demonstrated that MUFTI could perform well in handling task increment issues, reducing catastrophic forgetting, and achieving trade-offs between multiple objectives.

As a collaborative framework designed to safeguard privacy,Federated Learning(FL) seeks to protect participants’ data throughout the training process. However, the framework still faces security risks from poisoning attacks, arising from the unmonitored process of client-side model updates. Most existing solutions address scenarios where less than half of clients are malicious, i.e., which leaves a significant challenge to defend against attacks when more than half of participants are malicious. In this paper, we propose a FL scheme, named FedAMM, that resists backdoor attacks across various data distributions and malicious client ratios. We develop a novel backdoor defense mechanism to filter out malicious models, aiming to reduce the performance degradation of the model. The proposed scheme addresses the challenge of distance measurement in high-dimensional spaces by applyingPrincipal Component Analysis(PCA) to improve clustering effectiveness. We borrow the idea of critical parameter analysis to enhance discriminative ability in non-iid data scenarios, via assessing the benign or malicious nature of models by comparing the similarity of critical parameters across different models. Finally, our scheme employs a hierarchical noise perturbation to improve the backdoor mitigation rate, effectively eliminating the backdoor and reducing the adverse effects of noise on task accuracy. Through evaluations conducted on multiple datasets, we demonstrate that the proposed scheme achieves superior backdoor defense across diverse client data distributions and different ratios of malicious participants. With 80% malicious clients, FedAMM achieves low backdoor attack success rates of 1.14%, 0.28%, and 5.53% on MNIST, FMNIST, and CIFAR-10, respectively, demonstrating enhanced robustness of FL against backdoor attacks.

Blockchain technology autonomously executes smart contracts that require external data to facilitate specific applications, underscoring the necessity for Authenticated Data Feeds (ADF). Existing solutions fall short in providing genuine authentication of data, lack private and verifiable computations across multiple data sources, and overlook data traceability, rendering current systems inadequate for complex applications. We present WuKong (WK), a data governance system that offers authenticated, privately verifiable, and traceable data feeds. WK enables a server to collect faithful data through an oracle committee and to prove computation correctness in zero-knowledge proofs, and empowers legal entities to trace a leakage source conditionally. We formally define and prove the security of WK in the universal composability framework. We implement three applications that seamlessly integrate with WK. Experimental results indicate that WK effectively liberates sensitive data from distributed, untrusted, and anonymous providers, making it accessible to various services and establishing trust in a decentralized world.

Side-channel analysis (SCA) based on machine learning, particularly neural networks, has gained considerable attention in recent years. However, previous works predominantly focus on establishing connections between labels and related profiled traces. These approaches primarily capture label-related features and often overlook the connections between traces of the same label, resulting in the loss of some valuable information. Besides, the attack traces also contain valuable information that can be used in the training process to assist model learning. In this paper, we propose a profiled SCA approach based on contrastive learning named CL-SCA to address these issues. This approach extracts features by emphasizing the similarities among traces, thereby improving the effectiveness of key recovery while maintaining the advantages of the original SCA approach. Through experiments of different datasets from different platforms, we demonstrate that CL-SCA significantly outperforms other approaches. Moreover, by incorporating attack traces into the training process using our approach, we can further enhance its performance. This extension can improve the effectiveness of key recovery, which is fully verified through experiments on different datasets.

The module-lattice-based digital signature standard, formerly known as CRYSTALS-DILITHIUM, is a lattice-based post-quantum cryptographic scheme. In August 2024, the National Institute of Standards and Technology officially standardized ML-DSA under FIPS 204. ML-DSA generates one valid signature and multiple rejected signatures during a single signing process. Most side-channel attacks targeting ML-DSA have focused solely on the valid signature, while largely neglecting the hints contained in rejected signatures. Building on prior SASCA frameworks originally proposed for ML-DSA, in this paper we present an efficient and fully practical instantiation of a private-key recovery attack on ML-DSA that jointly exploits side-channel leakages from both valid and rejected signatures within a unified factor graph. This concrete instantiation maximizes the information extracted from a single signing attempt and minimizes the number of required traces for full key recovery. We conducted a proof-of-concept experiment with both reference and ASM-optimized implementations on a Cortex-M4 core chip, where the results demonstrate that incorporating rejected signatures reduces the required number of traces by at least 50.0% for full key recovery. Moreover, we show that using only rejected signatures suffices to recover the key with fewer than 30 traces under our setup. Our findings highlight that protecting rejected signatures is crucial, as their leakage provides valuable side-channel information. We strongly recommend implementing countermeasures for rejected signatures during the signing process to mitigate potential threats.

This paper introduces the Deferred Byzantine Generals Problem, a variant of the Byzantine Generals Problem which focuses on ensuring replicas maintain consistency over timed-release secret operations (operations that can only be known after a specified time or event). The solution to the problem is called the Deferred Byzantine Fault Tolerant (DBFT) consensus. DBFT can operate exclusive or be interleave with BFTs to handle specific tasks at designated sequence numbers or views, thereby facilitating the implementation of certain system-desirable features or supporting novel applications. It does not rely on existing timed-release primitives, but instead ensures its timed-release property through voting interactions. We presents the system model of DBFT SMR under partial synchronization using Threshold Public Key Encryption (TPKE) as the cryptographic primitives, highlighting the core issues. Then we design and implement the DBFT protocol using PBFT notations, focusing on the unique parts to facilitate expansions to other paradigms. Through experimental results, we show the impact of different executing modes and parameter choices on performance and discuss potential optimizations.

Provable Data Possession (PDP) is an alternative technique that guarantees the integrity of remote data. However, most current PDP schemes are inapplicable to similarity-like data checking with the same attribute, i.e., when there are numerous similar files to be checked by Data Owners (DOs). Some traditional models cannot resist the corrupt auditors who always generate biased challenge information. Besides, a copy-summation attack exists in some schemes, which means the Cloud Server (CS) can bypass the verification by storing the median value instead of initial data via summation operation. To address the issues above, in this work, we propose a keyword searchable PDP scheme for large similar data checking. To achieve searchability, we introduce the notion of a keyword in PDP and design a specific index structure to match the authenticator. The scheme enables all matched files to be auditable and verifiable, while guaranteeing privacy protections. Unlike existing methods, our Third Party Auditor (TPA) checks all similar data containing the same keyword simultaneously. We utilize unpredictable yet verifiable public information on the blockchain to generate challenge information, rather than relying on a centralized TPA. The proposed scheme can resist copy-summation attacks. Theoretical analysis demonstrates that the proposed scheme satisfies the security requirements, and our evaluations demonstrate its efficiency.

To boost the encoder stealing attack under the perturbation-based defense that hinders the attack performance, we propose a boosting encoder stealing attack with perturbation recovery named BESA. It aims to overcome perturbation-based defenses. The core of BESA consists of two modules: perturbation detection and perturbation recovery, which can be combined with canonical encoder stealing attacks. The perturbation detection module utilizes the feature vectors obtained from the target encoder to infer the defense mechanism employed by the service provider. Once the defense mechanism is detected, the perturbation recovery module leverages the well-designed generative model to restore a clean feature vector from the perturbed one. Through extensive evaluations based on various datasets, we demonstrate that BESA significantly enhances the surrogate encoder accuracy of existing encoder stealing attacks by up to 24.63% when facing state-of-the-art defenses and combinations of multiple defenses.

Traffic encryption is widely used to protect communication privacy but is increasingly exploited by attackers to conceal malicious activities. Existing malicious encrypted traffic detection methods rely on large amounts of labeled samples for training, limiting their ability to quickly respond to new attacks. These methods also are vulnerable to traffic obfuscation strategies, such as injecting dummy packets. In this paper, we proposeSmartDetector, a robust malicious encrypted traffic detection method via contrastive learning. We first propose a novel traffic representation named Semantic Attribute Matrix (SAM), which can effectively distinguish between malicious and benign traffic. We also design a data augmentation method to generate diverse traffic samples, which makes the detection model more robust against different traffic obfuscation strategies. We propose a malicious encrypted traffic classifier that first pre-trains a model via contrastive learning to learn deep representations from unlabeled data, then fine-tunes the model with a supervised classifier to achieve accurate detection even with only a few labeled samples. We conduct extensive experiments with five public datasets to evaluate the performance of SmartDetector. The results demonstrate that it outperforms the state-of-the-art (SOTA) methods in three typical scenarios. Specifically, in the evasion attack detection scenario, SmartDetector achieves an F1 score and AUC above 93%, with average improvements of 19.84% and 18.17% over the SOTA method, respectively.

Federated Learning (FL) allows multiple data owners to jointly train machine learning models by sharing local models instead of raw private data, alleviating data privacy concerns. However, as the local computation of data owners is unpredictable, it increases its vulnerability to Byzantine attacks, where compromised data owners submit abnormal local models that can severely degrade global model accuracy. Existing Byzantine-robust FL methods depend on a semi-honest server executing predefined Byzantine-robust aggregation rules (ByRules) to filter out abnormal local models, but these methods fail when the server is compromised. Although recent serverless Byzantine-robust FL approaches mitigate the risk of a compromised server, they suffer from challenges in achieving consensus on ByRules and impose a heavy burden on privacy protection. In this paper, we propose ROBY, a novel serverless FL framework that extends existing ByRules to a decentralized setting, effectively defending against Byzantine attacks and ensuring privacy protection for local models. ROBY introduces a shared, dynamically updated consensus dataset that serves as a reliable benchmark for applying ByRules and enabling efficient consensus on ByRules among decentralized data owners. Moreover, we design a dual-layer privacy shielding strategy in ROBY to protect local model privacy without sacrificing global model accuracy or incurring extra computational and communication overhead. Extensive evaluations demonstrate that ROBY substantially enhances both Byzantine robustness and privacy protection compared to server-based FL methods.

Privacy-preserving Federated Learning (FL) based on Differential Privacy (DP) protects clients’ data by adding DP noise to samples’ gradients and has emerged as a de facto standard for data privacy in FL. However, the accuracy of global models in DP-based FL may be reduced significantly when rogue clients occur who deviate from the preset DP-based FL approaches and selfishly inject excessive DP noise beyond expectations, thereby applying a smaller privacy budget in the DP mechanism to ensure a higher level of security. Existing DP-based FL fails to prevent such attacks as they are imperceptible. Under the DP-based FL system and random Gaussian noise, the local model parameters of the rogue clients and the honest clients have identical distributions. In particular, the rogue local models show a low performance, but directly filtering out lower-performance local models compromises the generalizability of global models, as local models trained on scarce data also behave with low performance in the early epoch. In this paper, we propose ReFL, a novel privacy-preserving FL system that enforces DP and avoids the accuracy reduction of global models caused by excessive DP noise of rogue clients. Based on the observation that rogue local models with excessive DP noise and honest local models trained on scarce data have different performance patterns in long-term training epochs, we propose a long-term contribution incentives scheme to evaluate clients’ reputations and identify rogue clients. Furthermore, we design a reputation-based aggregation to avoid the damage of rogue clients’ models on the global model accuracy, based on the incentive reputation. Extensive experiments demonstrate ReFL guarantees the global model accuracy performance 0.77% - 81.71% higher than existing DP-based FL methods in the presence of rogue clients.

Vertical federated learning (VFL) provides a privacy-preserving method for machine learning, enabling collaborative training across multiple institutions with vertically distributed data. Existing VFL methods assume that participants passively gain local models of the same structure and communicate with active pary during each training batch. However, due to the heterogeneity of participating institutions, VFL with heterogeneous models for efficient communication is indispensable in real-life scenarios. To address this challenge, we propose a new VFL method called Practical Heterogeneous Vertical Federated Learning via Representation Learning (PraVFed) to support the training of parties with heterogeneous local models and reduce communication costs. Specifically, PraVFed employs weighted aggregation of local embedding values from the passive party to mitigate the influence of heterogeneous local model information on the global model. Furthermore, to safeguard the passive party’s local sample features, we utilize blinding factors to protect its local embedding values. To reduce communication costs, the passive party performs multiple rounds of local pre-model training while preserving label privacy. We conducted a comprehensive theoretical analysis and extensive experimentation to demonstrate that PraVFed reduces communication overhead under heterogeneous models and outperforms other approaches. For example, when the target accuracy is set at 60% under the CINIC10 dataset, the communication cost of PraVFed is reduced by 70.57% compared to the baseline method. Our code is available athttps://github.com/wangshuo105/PraVFed_main.

Differential privacy (DP) has been proven to be an effective universal solution for privacy protection in language models. Nevertheless, the introduction of DP incurs significant computational overhead. One promising approach to this challenge is to integrate Parameter Efficient Fine-Tuning (PEFT) with DP, leveraging the memory-efficient characteristics of PEFT to reduce the substantial memory consumption of DP. Given that fine-tuning aims to quickly adapt pretrained models to downstream tasks, it is crucial to balance privacy protection with model utility to avoid excessive performance compromise. In this paper, we propose a Relevance-based Adaptive Private Fine-Tuning (Rap-FT) framework, the first approach designed to mitigate model utility loss caused by DP perturbations in the PEFT context, and to achieve a balance between differential privacy and model utility. Specifically, we introduce an enhanced layer-wise relevance propagation process to analyze the relevance of trainable parameters, which can be adapted to the three major categories of PEFT methods. Based on the relevance map generated, we partition the parameter space dimensionally, and develop an adaptive gradient perturbation strategy that adjusts the noise addition to mitigate the adverse impacts of perturbations. Extensive experimental evaluations are conducted to demonstrate that our Rap-FT framework can improve the utility of the fine-tuned model compared to the baseline differentially private fine-tuning methods, while maintaining a comparable level of privacy protection.

Subsequently, by executing various attacks on benchmark datasets such as MNIST, we construct Federated Learning Malicious Parameter Identification (FLMPID) dataset to enable malicious client detection. Building on this dataset, we propose FORTRESS (Federated POisoning-Resistance Defense via Dual-Domain Distance and TRust AssESSment), a framework designed to detect and mitigate malicious updates from clients. FORTRESS employs a unique encoder-decoder architecture. The encoder utilizes dual-domain distance metrics on weights and gradients to extract hidden representations, while the decoder leverages Actor-Critic (AC) reinforcement learning for trust assessment. We evaluated FORTRESS under multiple attack scenarios and demonstrated its defense effectiveness, making it a promising solution for enhancing the security of FL systems.

Neural network inference in cloud service offers tangible benefits to users, from individuals and small institutions to large companies. However, two crucial concerns must be addressed. The first arises in satisfying the privacy of the model, the input data, and the inference results throughout the inference process. The second pertains to verifying that the inferences are derived from the designated neural network model. Although Secure Multi-Party Computation (MPC) and Zero-Knowledge Proof (ZKP) are typically adopted to mitigate such issues, the major challenge lies in achieving privacy preservation and verifiability simultaneously. In this study, we address both issues by proposing VSecNN, a verifiable and privacy-preserving neural network inference scheme. Specifically, we integrate MPC with the Zero-Knowledge Succinct Non-Interactive Argument of Knowledge (zk-SNARK) protocol to achieve zero-knowledge proof generation for multiple parties. Subsequently, we perform adaptive optimizations on the multi-party proof generation approach to align with the neural network, thereby achieving both privacy-preserving capabilities and verifiability. Experimental results demonstrate an improvement in the efficiency. For example, the computation time for completing our multi-party proof generation could be as low as 1.7 times that of the single-party proof generation, while the verification requires only 169ms on the MNIST dataset.

As the leading privacy coin, Monero is widely recognized for its high level of anonymity. Monero utilizes linkable ring signature to hide the sender of a transaction. Although the anonymity is preferred by users, it poses challenges for authorities seeking to regulate financial activities. Researchers are actively engaged in studying methods to de-anonymize Monero. Previous methods usually relied on a specific type of ring called zero-mixin ring. However, these methods have become ineffective after Monero enforced the minimum ringsize. In this paper, we propose a novel approach based on maximum weighted matching to de-anonymize Monero. The proposed approach does not rely on the existence of zero-mixin rings. Specifically, we construct a weighted bipartite graph to represent the relationship between rings and transaction outputs. Based on the empirical probability distribution derived from users’ spending patterns, three weighting methods are proposed. Accordingly, we transform the de-anonymization problem into a maximum weight matching (MWM) problem. Due to the scale of the graph, traditional algorithms for solving the MWM problem are not applicable. Instead, we propose a deep reinforcement learning-based algorithm that achieves near-optimal results. Experimental results on both real-world dataset and synthetic dataset demonstrate the effectiveness of the proposed approach.

Cross-modal semantic retrieval systems face significant privacy risks due to storing plaintext data on cloud servers. We propose PCSR, a privacy-preserving framework enabling semantic search directly on encrypted high-dimensional data. It consists of three essential modules: a cross-modal encoder, an approximate nearest neighbor (ANN) search algorithm, and an encryption algorithm. Specifically, we utilize CLIP, a deep neural network model, to extract features of images and texts. We design two ANN search methods for high-dimensional feature vectors by utilizing the space partitioning technique and Singular Value Decomposition algorithms, respectively. Furthermore, we employ adapted Random Matrix Multiplication (RMM) for efficient and secure vector similarity computations. Our rigorous security analysis demonstrates that our proposed schemes are secure. We conduct experiments on four datasets and systematically compare the performance of different encrypted retrieval methods. The superior performance validates the feasibility and efficiency of our proposed schemes.

Smart grid, through networked smart meters employing the non-intrusive load monitoring (NILM) technique, can considerably discern the usage patterns of residential appliances. However, this technique also incurs privacy leakage. To address this issue, we propose an innovative scheme based on adversarial attack in this paper. The scheme effectively prevents NILM models from violating appliance-level privacy, while also ensuring accurate billing calculation for users. To achieve this objective, we overcome two primary challenges. First, as NILM models fall under the category of time-series regression models, direct application of traditional adversarial attacks designed for classification tasks is not feasible. To tackle this issue, we formulate a novel adversarial attack problem tailored specifically for NILM and providing a theoretical foundation for utilizing the Jacobian of the NILM model to generate imperceptible perturbations. Leveraging the Jacobian, our scheme can produce perturbations, which effectively misleads the signal prediction of NILM models to safeguard users' appliance-level privacy. The second challenge pertains to fundamental utility requirements, where existing adversarial attack schemes struggle to achieve accurate billing calculation for users. To handle this problem, we introduce an additional constraint, mandating that the sum of added perturbations within a billing period must be precisely zero. Experimental validation on real-world power datasets REDD and U.K.-DALE demonstrates the efficacy of our proposed solutions, which can significantly amplify the discrepancy between the output of the targeted NILM model and the actual power signal of appliances, and enable accurate billing at the same time. Additionally, our solutions exhibit transferability, making the generated perturbation signal from one target model applicable to other diverse NILM models.

In the era of the Internet of Things (IoT), managing the deluge of data generated by distributed devices presents unique challenges, particularly concerning privacy and the efficient use of computational resources. Vertical Federated Learning (VFL) offers a promising avenue for collaborative machine learning without centralizing data, thereby addressing privacy concerns inherent in traditional approaches. However, as data privacy laws and personal data deletion requests become more prevalent, the necessity for effective machine unlearning strategies within VFL frameworks grows increasingly important. To this end, this paper introduces a novel approach to feature-based machine unlearning tailored specifically for VFL systems in IoT networks. Our methodology enables the selective removal of data influence from trained models without the need for full retraining, thus preserving model utility while ensuring compliance with privacy requirements. By integrating a combination of feature relevance measuring techniques and efficient communication protocols, our solution minimizes the data footprint on network nodes, reduces bandwidth consumption, and maintains the integrity and performance of the learning models. To the best of our knowledge, our proposed framework represents the first practical approach to enable machine unlearning within vertical federated learning environments. We demonstrate the effectiveness of our approach through rigorous evaluation using several IoT datasets, highlighting significant improvements in unlearning efficiency and model robustness compared to existing techniques. Our work not only furthers the development of sustainable and compliant machine learning models in IoT but also sets a foundational framework for future research in secure and efficient data management within federated environments.

Vertical Federated Learning (VFL) allows collaborative machine learning without sharing local data. However, existing VFL methods face challenges when dealing with heterogeneous local models among participants, which affects optimization convergence and generalization of participants' local knowledge aggregation. To address this challenge, this paper proposes a novel approach calledEmbeddingAggregation-based HeterogeneousModelsTraining in Vertical Federated Learning(EASTER). EASTER focuses on aggregating the local embeddings of each participant's knowledge during forward propagation. We propose an embedding protection method based on lightweight blinding factors, which injects the blinding factors into the local embedding of the passive party. However, the passive party does not own the sample labels, so the local model's gradient cannot be calculated locally. To overcome this limitation, we propose a new method in which the active party assists the passive party in computing its local heterogeneous model gradients. Theoretical analysis and extensive experiments demonstrate that EASTER can simultaneously train multiple heterogeneous models and outperform some recent methods in model performance. For example, compared with the state-of-the-art method, the model accuracy of EASTER was improved by 7.22% under the CIFAR-10 dataset.

Visible-infrared person re-identification (VIReID) primarily deals with matching identities across person images from different modalities. Due to the modality gap between visible and infrared images, cross-modality identity matching poses significant challenges. Recognizing that high-level semantics of pedestrian appearance, such as gender, shape, and clothing style, remain consistent across modalities, this paper intends to bridge the modality gap by infusing visual features with high-level semantics. Given the capability of Contrastive Language-Image Pre-training (CLIP) to sense high-level semantic information corresponding to visual representations, we explore the application of CLIP within the domain of VIReID. Consequently, we propose a CLIP-Driven Semantic Discovery Network (CSDN) that consists of Modality-specific Prompt Learner, Semantic Information Integration (SII), and High-level Semantic Embedding (HSE). Specifically, considering the diversity stemming from modality discrepancies in language descriptions, we devise bimodal learnable text tokens to capture modality-private semantic information for visible and infrared images, respectively. Additionally, acknowledging the complementary nature of semantic details across different modalities, we integrate text features from the bimodal language descriptions to achieve comprehensive semantics. Finally, we establish a connection between the integrated text features and the visual features across modalities. This process embed rich high-level semantic information into visual representations, thereby promoting the modality invariance of visual representations. The effectiveness and superiority of our proposed CSDN over existing methods have been substantiated through experimental evaluations on multiple widely used benchmarks.

Preserving the privacy of transactions and ensuring the regulatory compliance of transactions are two important requirements for blockchain-based financial applications. However, these two requirements are somewhat contradictory. Techniques for protecting transaction privacy, such as data encryption and zero-knowledge proof, generally make it difficult to regulate and audit the transactions. In this paper, we propose a system named zkFabLedger which enhances both the privacy and the auditability of the classic permissioned blockchain platform Hyperledger Fabric. The proposed system utilizes commitments and non-interactive zero-knowledge proofs to hide the detailed information of transactions while enabling the endorsing peer nodes to verify the regulatory compliance of transactions. Transactions are recorded on table-structured ledgers, so that the regulator can perform complex auditing of transactions. Moreover, we utilize the ring signature scheme and the secret handshake protocol to ensure the anonymity of the transaction sender while enabling the regulator to trace the sender’s identity. Simulation results demonstrate that the proposed system can balance well between privacy, regulation and efficiency.

With the flourishing of global services, low-latency analytics on large-volume geo-distributed data has been a regular requirement for application decision-making. Serverless computing, with its rapid function start-up and lightweight deployment, provides a compelling way for geo-distributed analytics. However, existing research focuses on elastic resource scaling at the stage granularity, struggling to heterogeneous resource demands across component functions in wide-area settings. The neglect potentially results in the cost inefficiency and Service Level Objective (SLO) violations. In this paper, we advocate for fine-grained function orchestration to exploit wide-area resource elasticity. We thereby present Demeter, a fine-grained function orchestrator that saves job execution costs for geo-distributed serverless analytics while ensuring SLO compliance. By learning from volatile and bursty environments, Demeter jointly makes per-function placement and resource allocation decisions using a well-optimized multi-agent reinforcement learning algorithm with a pruning mechanism. It prevent the irreparable performance loss by function congestion control. Ultimately, we implement Demeter and evaluate it with the realistic workloads. Experimental results reveal that Demeter outperforms the baselines by up to 46.6% on cost, while reducing SLO violation by over 23.7% and bringing it to below 15%.

Leader-based BFT systems face potential disruption and performance degradation from malicious leaders, with current solutions often lacking scalability or greatly increasing complexity. In this paper, we introduce ABSE, an Adaptive Baseline Score-based Election approach to mitigate the negative impact of malicious leaders on leader-based BFT systems. ABSE is fully localized and proposes to accumulate scores for processes based on their contribution to consensus advancement, aiming to bypass less reliable participants when electing leaders. We present a formal treatment of ABSE, addressing the primary design and implementation challenges, defining its generic components and rules for adherence to ensure global consistency. We also apply ABSE to two different BFT protocols, demonstrating its scalability and negligible impact on protocol complexity. Finally, by building a system prototype and conducting experiments on it, we demonstrate that ABSE-enhanced protocols can effectively minimize the disruptions caused by malicious leaders, whilst incurring minimal additional resource overhead and maintaining base performance.

A key management service (KMS) is vital to modern mission-critical systems. At the core of KMS are the key generation process and the key refresh process. In this paper, we design and implement a purely asynchronous system for completely distributed KMS supporting traditional applications such as threshold cryptosystems and multiparty computation (MPC) as well as emerging blockchains and Web3 applications. In this system, we have built a number of new asynchronous distributed key generation (ADKG) protocols and their corresponding asynchronous distributed key refresh (ADKR) protocols. We have demonstrated that our ADKG and ADKR protocols in the standard model outperform existing ones of the same kind, while our protocols in the random oracle model (ROM) are more efficient than other protocols with small and medium-sized networks.

Blockchain’s inherent immutability, while transformative, creates critical security risks in smart contracts, where undetected vulnerabilities can result in irreversible financial losses. Current auditing tools and approaches often address specific vulnerability types, yet there is a need for a comprehensive solution that can detect a wide range of vulnerabilities with high accuracy. We propose LLM-SmartAudit, a novel framework that leverages Large Language Models (LLMs) to automate smart contract vulnerability detection and analysis. Using a multi-agent conversational architecture with a buffer-of-thought mechanism, LLM-SmartAudit maintains a dynamic record of insights generated throughout the audit process. This enables a collaborative system of specialized agents to iteratively refine their assessments, enhancing the accuracy and depth of vulnerability detection. To evaluate its effectiveness, LLM-SmartAudit was tested on three datasets: a benchmark for common vulnerabilities, a real-world project corpus, and a CVE dataset. It outperformed existing tools with 98% accuracy on common vulnerabilities and demonstrates higher accuracy in real-world scenarios. Additionally, it successfully identifies 12 out of 13 CVEs, surpassing other LLM-based methods. These results demonstrate the effectiveness of multi-agent collaboration in automated smart contract auditing, offering a scalable, adaptive, and highly efficient solution for blockchain security analysis.

As blockchain technology becomes prevalent, smart contracts have shown significant utility in finance and supply chain management. However, vulnerabilities in smart contracts pose serious threats to blockchain security, leading to substantial economic losses. Therefore, developing effective vulnerability detection solutions is urgent. To address this issue, we propose a method for detecting vulnerabilities in smart contracts using graph neural networks (GNNs) that can identify eight common vulnerabilities. Our method is fully automated, applicable to all Ethereum smart contracts, and does not require expert-defined rules or manually defined features. We extract the Control Flow Graph and Abstract Syntax Graph from the smart contract code, which are then processed by a GNN to generate feature vectors for classification. Experiments on a real Ethereum dataset demonstrate that our method significantly outperforms existing state-of-the-art approaches. For individual detection tasks, the combined source code and bytecode method achieves an average accuracy of 95.78%, with a peak of 99.13%, and an average F1 score of 93.80%. Compared to competitors, our method shows an average improvement of 51.92% in accuracy and 47.21% in F1 score. The bytecode-only method achieves an average accuracy of 94.68% and an F1 score of 92.36%. For multi-class tasks, both methods achieve high accuracies of 91.26% and 87.34%, with F1 scores of 97.42% and 96.43%, respectively.

The widespread developments of blockchain bring about diverse blockchain networks, where each stands as an isolated data island and operates independently. The need of interoperability and interconnection among kinds of blockchains inspires the emergence of the cross-chain technology. It enables the asset transfer and information interaction via crosschain transactions. The previous cross-chain transaction systems are almost implemented over the plain data, fully exposing the transaction-associated information. Cryptographic techniques such as non-interactive zero-knowledge proof can be used to protect the transaction privacy, while its high complexity incurs heavy running cost. The privacy of cross-chain transactions is still a challenging issue. In this paper, we propose a lightweight crosschain transaction privacy-preserving method named PTCross. It embeds Bulletproofs and Pedersen commitment to hide crosschain transaction information, meanwhile combining off-chain computation and on-chain contract verification. We instantiate and implement PTCross between ChainMaker and Bitcoin. The experimental results show that the proposed PTCross achieves both lightweight performance and strong privacy.

Foundation models have demonstrated remarkable capabilities in various tasks such as natural language processing, content generation, and complex reasoning and have the potential to spark new technology and application revolutions in the industrial domain. However, Industrial Foundation Models (IFMs) remain almost unexplored, and the industrial sector has domain-specific issues and challenges to address when harnessing the capabilities of foundation models. Therefore, we introduce the concept and construction paradigm of IFMs and propose a 5-dimensional general framework of the IFMs. Moreover, we present the key research issues and technologies of IFMs and discuss some advanced and potential industrial applications. We hope this paper can serve as a useful resource for researchers seeking to innovate within the domain of IFMs.

Large Language Models (LLMs) have revolutionized open-domain dialogue agents but encounter challenges in multi-character roleplaying (MCRP) scenarios.To address this issue, this work presents Neeko, an innovative framework designed for efficient multiplecharacter role-playing.The proposed framework breaks down the role-playing agent's training process into agent pre-tuning, multiple character playing, and character incremental learning, effectively handling both seen and unseen roles.Neeko employs a dynamic low-rank adapter (LoRA) strategy by training separate LoRA blocks independently for each character, alongside incorporating a gating network for role selection.This design allows Neeko to seamlessly adjust to a wide range of characters, thereby bolstering its adaptability to distinctive attributes, personalities, and speech patterns.As a result, Neeko demonstrates superior performance in MCRP over most existing methods, offering more engaging and versatile user interaction experiences.

Biometrics is a technology that utilizes individual physiological or behavioral characteristics for identity authentication and identification, ensuring secure and accurate identity verification by comparing biometric information with samples in a database. However, traditional biometric technology raises concerns about privacy leakage, which has led to the emergence of privacy-preserving biometric technology. This study introduces a cloud-assisted privacy-preserving biometric authentication system based on multi-key full homomorphic encryption. Our scheme employs a TFHE encryption scheme to encrypt user biometrics and utilizes a cloud server to assist in computation. We design secure computing protocols based on multi-key TFHE and develop a privacy-preserving biometric system based on a single cloud server. Privacy analysis and performance evaluation demonstrate that the proposed solution is efficient and feasible. Our experimental findings indicate that the proposed scheme exhibits a superior accuracy rate to current schemes. Compared to the best solution, our method has increased the iris recognition accuracy by approximately 68.42%. Although the experimental results demonstrate high accuracy and feasibility, implementing TFHE in biometric models could be improved by its execution time, presenting challenges for broad adoption. Nevertheless, through optimization and technological advancements, this protocol is anticipated to elevate privacy protection standards in practical biometric recognition systems moving forward.

Recently, path inference-based knowledge graph reasoning (KGR) methods have attracted great attention due to their good performance and interpretability. However, as the number of hops increases, the search space grows exponentially, making the reward sparse and the process of reasoning difficult. To alleviate this problem, we propose the Multimodality-guided Hierarchical Policy Search (MHPS) for KGR, which introduces multimodal hierarchical guidance to each layer of policies during policy search. On the one hand, multimodal guidance reserves rich information on different dimensions, providing more opportunities to find better paths. On the other hand, this leads to better interaction between the two agents, resulting in more concise guidance for policy stepping. Experimental results on two public datasets demonstrate that the proposed approach outperforms state-of-the-art methods on multi-hop KGR.

Graph neural networks (GNNs) have been widely applied in various graph analysis tasks. To provide more convenient and faster predictive services, many enterprises are choosing to deploy GNNs in cloud environments. However, given the increasing privacy concerns about GNNs models and graph data, as well as the need to quickly generate embeddings for new nodes in real-world applications, a critical issue in this emerging paradigm is to ensure the security and scalability of GNN predictions. In this paper, we propose a privacy-preserving and scalable GNN prediction scheme, named PS-GNN, to address the privacy issues in cloud environments. Specifically, PS-GNN utilizes a customized array structure to store graph data and employs secret sharing to preserve the confidentiality of both the GNN model and graph data. Besides, the scalability of PS-GNN is achieved by aggregating feature information from local node neighborhoods in parallel. Through a detailed analysis, we demonstrate the security of PS-GNN. Extensive experiments on real-world datasets demonstrate that PS-GNN outperforms existing schemes in terms of computational and communication overhead, and reaches state-of-the-art performance on large graphs.

With the widespread use of cryptocurrencies and the development of anonymity network technology, how to effectively identify cryptocurrency transactions through anonymity networks such as Tor has become a major challenge in cybersecurity. We introduce a new traffic correlation technique, TSMCorr, aimed at identifying cryptocurrency transactions through anonymous networks like Tor. Traditional traffic correlation methods struggle with the high cost of deployment, while we leverage advanced feature engineering and deep learning, including a Traffic Volume Matrix (TSM), to develop a more accurate and efficient flow correlation model. TSMCorr not only improves upon existing methods in terms of F1 score by $15.5 \%$ on DeepCoFFEA dataset, but also lowers the computational time by $89 \%$, RAM consumption by $77.4 \%$, and model parameters by $11.5 \%$.

Blockchain-based steganography enables data hiding via encoding the covert data into a specific blockchain transaction field. However, previous works focus on the specific field-embedding methods while lacking a consideration on required field-generation embedding. In this paper, we propose GBSF, a generic framework for blockchain-based steganography. The sender generates the required fields, where the additional covert data is embedded to enhance the channel capacity. Based on GBSF, we design R-GAN that utilizes the generative adversarial network (GAN) with a reversible generator to generate the required fields and encode additional covert data into the input noise of the reversible generator. We then explore the performance flaw of R-GAN and introduce CCR-GAN as an improvement. CCR-GAN employs a counter-intuitive data preprocessing mechanism to reduce decoding errors in covert data. It incurs gradient explosion for model convergence and we design a custom activation function. We conduct experiments using the transaction amount of the Bitcoin mainnet as the required field. The results demonstrate that R-GAN and CCR-GAN allow to embed 11-bit (embedding rate of 17.2%) and 24-bit (embedding rate of 37.5%) covert data within a transaction amount, and enhance the channel capacity of state-of-the-art works by 4.30% to 91.67% and 9.38% to 200.00%, respectively.

In the era of global services, low-latency analytics on large-volume geo-distributed data has been a regular demand for application decision-making. Serverless computing facilitates fast function start-up and deployment, making it an attractive way for geo-distributed analytics. We argue that the serverless paradigm holds the potential to breach current performance bottlenecks via fine-grained function orchestration. However, how to configure it for geo-distributed analytics remains ambiguous. To fill this gap, we present Demeter, a scalable fine-grained function orchestrator for geo-distributed serverless analytics systems. Demeter aims to minimize the composite cost of co-existing jobs while meeting the user-specific Service Level Objectives (SLO). To handle the volatile environments and learn the diverse function demands, a Multi-Agent Reinforcement Learning (MARL) solution is used to co-optimize the per-function placement and resource allocation. The MARL extracts holistic and compact states via hierarchical graph neural networks, and then designs a novel actor network to shrink the huge decision space and model complexity. Finally, we implement Demeter and evaluate it using realistic workloads. The experimental results reveal that Demeter significantly saves costs by 23.3%∼32.7%, while reducing SLO violations by over 27.4%, surpassing state-of-the-art solutions.

The Internet of Vehicles (IoV) facilitates wireless communication and information exchange among vehicles, road infrastructure, and pedestrians, creating a comprehensive network for intelligent vehicle control. Within the IoV framework, numerous computing tasks typically transmitted to the cloud for centralized processing lead to significant latency and substantial cloud computing burdens. To optimize IoV efficiency while safeguarding vehicle data privacy, federated learning (FL) has shown promising potential. However, due to vehicle mobility, FL encounters challenges such as communication bandwidth limitations, varying road conditions, and data transmission delays. Additionally, traditional FL methods do not fully ensure the non-disclosure of user data during aggregation. To address these issues, we propose a lightweight encryption-based asynchronous federated learning scheme (LPAsyFL) for privacy protection in IoV. This scheme supports user participation and withdrawal, ensuring security in honest but curious environments. By utilizing lightweight cryptographic primitives and asynchronous aggregation techniques, we introduce a dynamic aggregation mechanism that reduces communication overhead and enhances model aggregation efficiency. Simulation results on various datasets demonstrate that our approach reduces communication costs and improves aggregation efficiency in the vehicular network.

Federated learning (FL) is a machine learning method that enables model training without centralizing data for integration. However, FL is vulnerable to poisoning attacks, in which an attacker manipulates the malicious clients to corrupt the global model via poisoning their local training data or model updates, resulting in compromised model accuracy and degraded performance. In addition, in FL, although the original data can be trained without leaving the local devices, some attackers can obtain the private information of training participants through model parameters, causing privacy leaks. In order to solve the above problems, we propose a privacy-preserving federated learning robust aggregation scheme based on secret sharing. This scheme is implemented based on secret sharing technology, protecting clients’ data privacy while achieving Byzantine-robust. Moreover, our scheme considers the two situations of honest majority and malicious majority of clients; that is, the model can effectively resist poisoning attacks when the proportion of malicious clients is less than 50% or more than 50%. Extensive experiments show that our scheme is secure against various common poisoning attacks and is more robust than some existing aggregation rules, even when malicious actors account for the majority.

Heuristic-based workload redistribution is the most commonly adopted solution to provide enhanced service performance in large-scale Internet Data Centers (IDCs). However, statistics show that they cannot perform as well as expected in real-world IDCs. In this paper, we rethink existing solutions based on real-world trace data and pinpoint two major pitfalls: (i) Sensitive to hand-tuning parameters; (ii) Reassigning only a few workloads locally at a time. The two of them jointly limit the universal applicability of existing solutions in optimizing multiple objectives fairly. To address such issues, we propose the matching-theory-based solution for workload redistribution, namely Themis. It is an efficient and universal solution for large-scale IDCs, which can avoid empirical parameters in optimization and reassign several workloads globally each time. Moreover, the newly proposed Themis can optimize multiple objectives (e.g., resource utilization balancing and communication efficiency improving) simultaneously and fairly. In addition to its own performance advantages, our proposed Themis is also compatible with existing methods, thus adapting to a wider range of deployment scenarios. Extensive evaluations based on the trace data from two real-world IDCs demonstrate that our proposed Themis outperforms multiple comparison solutions, as well as the compatibility of parameter changes (i.e., stability properties in terms of parameter configuration).

Website Fingerprinting (WF) attacks significantly threaten user privacy in anonymity networks such as Tor. While numerous defenses have been proposed, they are unable to efficiently defend against recent deep learning based WF attacks. In this paper, we propose Palette, a novel and practical WF defense that utilizes traffic cluster anonymization to protect live Tor traffic. By clustering websites with high similarity in traffic patterns and regulating them into a well-designed uniform pattern for a cluster (i.e., a group of similar websites), Palette prevents attackers from distinguishing between these similar websites within the cluster and further provides a strong anonymity guarantee. Comprehensive evaluations with public real-world datasets show that Palette is superior to the existing defenses, greatly reducing the accuracy of the state-of-the-art (SOTA) WF attacks with acceptable overheads. Furthermore, we implement Palette as a Pluggable Transport in the Tor network. The experiment results demonstrate that, on average, Palette effectively reduces the accuracy of the SOTA WF attacks by 73.60%, which improves the existing defenses by 33.50%-43.47%.

In this article, we introduce the concept of edge computing power network (EdgeCPN) as a new paradigm to facilitate elastic integration and flexible scheduling of computing resources for task offloading in computing power networks (CPNs). Previous studies mainly focused on scheduling computing resources in the vertical dimension and may not effectively consider the computing resources selection in CPNs with increasingly diverse computing resources, which results in inefficient and unstable computing resource scheduling performance for task offloading. In this article, we design an on-demand computing resource scheduling model to enable efficient task offloading in EdgeCPNs. To improve the search efficiency and stability, we decouple the search for task offloading problems in EdgeCPNs into two stages and present a two-stage evolutionary search scheme (TESA). In stage-1, TESA first optimizes computing resources selection by searching a computing resources subset depending on the user budget, with the objective of maximizing the total gain. In stage-2, TESA jointly optimizes task offloading decisions and computing resources allocations based on the subset found in stage-1, with the objective of minimizing total delay. Numerical results confirm that the proposed scheme significantly enhances the efficiency and stability of the computing resources scheduling performance for task offloading in EdgeCPNs.

The proliferation of the Internet of Things (IoT) has amplified the necessity for secure data transmission. Lightweight block ciphers are pivotal in fortifying the security of IoT systems, yet the resource-constrained nature of IoT often limits the complexity of their designs, especially the linear layer in typical substitution-permutation network (SPN) and Feistel designs. This study investigates the vulnerability of seven lightweight block ciphers—specifically, CRAFT, Midori, SKINNY, MANTIS, LBlock, TWINE, and WARP, each catering to diverse application demands—concerning their susceptibility to mixture differential (MD) cryptanalysis. Modifying an automated tool based on linear programming, we identify MD distinguishers associated with these ciphers, exhibiting a higher number of rounds than that observed in the widely adopted AES block cipher. This disparity suggests that the simplified linear layer adopted by the lightweight block ciphers potentially compromises their resistance to MD distinguisher construction. Nevertheless, this compromise is counterbalanced by an augmented incorporation of rounds within the cipher design. Pertaining to the notion of security margins—denoting the percentage of rounds beyond the scope of constructed MD distinguishers relative to the total number of full rounds—the lightweight block ciphers subjected to scrutiny manifest elevated security margins, thereby demonstrating heightened resilience against MD cryptanalysis. This research provides a comprehensive security evaluation of the target lightweight block ciphers and introduces a versatile evaluation tool that can be adapted for the analysis of other aligned lightweight block ciphers in the context of MD cryptanalysis.

With integrity and traceability, blockchains have been widely applied in Internet of Things (IoT) systems. However, immutable blockchains contradict recent data regulations (e.g., the right to be forgotten in General Data Protection Regulation), making redactable blockchain-based IoT emerge as a promising paradigm. In this paradigm, IoT users can specify expressive policies (i.e., containing multiple logical AND and OR operators) to achieve controllable data editability. Unfortunately, existing related schemes with expressive policies face several issues: high communication costs, data privacy leakage (i.e., data can be read by all users), and inefficient user revocation. This article proposes a privacy-preserving and revocable redactable blockchain scheme in IoT systems, named BlockENC. BlockENC allows owners to specify expressive policies for controlling which users can read or edit their data and ensures downward compatible privileges (i.e., editable users own the privilege of readable users but not vice versa) under only$\mathcal {O}(n)$communication costs$(\mathcal {O}(n^{2})$in other schemes). The punchline of BlockENC is to define readability policies as subsets of editability policies and introduce access control trees to embed these policies in distributing data decryption keys and chameleon hash trapdoors. Moreover, drawing inspiration from ciphertext division mechanisms in proxy re-encryption techniques, BlockENC creates globally unique random values to reconstruct user keys, converting updating all existing keys or ciphertexts when user revocation cases occur into simply invalidating corresponding keys. Security analysis proves that BlockENC is secure against chosen-plaintext attacks. Experiments on the FISCO blockchain platform show that BlockENC achieves around$5\times $computation and$10\times $communication improvement over related works.

Privacy-preserving truth discovery, as a data aggregation algorithm that can extract reliable results from disparate and conflicting data in a privacy-preserving manner, has received a lot of attention in ensuring the reliability and privacy of data in mobile crowdsensing systems. However, most of the existing work requires that workers must stay online all the time during the full process of truth discovery. Although a few recent schemes have been proposed to tolerate worker dropout, they are tailored for a single-round setting. Repeating these schemes several times to adapt to the truth discovery will introduce significant computational and communication overheads, especially for the workers. To solve the above challenges, in this paper, we propose a multi-round efficient and secure truth discovery scheme in mobile crowdsensing systems that can balance the 3-way trade-off between privacy protection, dropout tolerance, and protocol efficiency. Specifically, we devise a novel mask generation capable of reusing secrets to eliminate the costly overhead of workers needing to recompute new secrets each round. Besides, we design a lightweight dropout tolerance mechanism to guarantee that even if workers drop out halfway, the server can still acquire meaningful truth. Rigorous security analysis and extensive experimental results demonstrate the privacy and efficiency of our scheme, respectively.

In cloud-based health monitoring services, healthcare centers often outsource support vector machine (SVM)-based clinical decision models to provide remote users with clinical decisions. During service provisioning, authorized external organizations like insurance companies aim to verify decision correctness to prevent fraudulent medical reimbursements. However, existing verifiable and secure SVM classification schemes have predominantly focused on user self-verification, thereby introducing potential risks of privacy leakage (such as input data exposure) in publicly verifiable scenarios. To address the aforementioned limitation, we propose a publicly verifiable and secure SVM classification scheme (PVSSVM) for cloud-based health monitoring services in a malicious setting, which can accommodate the verification needs of users or authorized external organizations with respect to potential malicious results returned by cloud servers. Specifically, we utilize homomorphic encryption and secret sharing to protect the model and data confidentiality in the cloud server, respectively. Based on a multiserver verifiable computation framework, PVSSVM achieves public verification of predicted results. Additionally, we further investigate its performance. Experimental evaluations demonstrate that PVSSVM outperforms existing state-of-the-art solutions in terms of computation and communication overhead. Notably, in the verification scenario of large-scale predictions, the proposed scheme achieves a reduction of approximately 83.71% in computation overhead through batch verification, as compared to one-by-one verification.

Blockchain uses smart contract technology to automate the execution of Internet of Things (IoT) data trading and facilitate the flow and application of IoT data. The verifiability of the blockchain system requires data to be open and transparent. Directly using smart contracts for IoT data trading may expose sensitive data generated by IoT devices, thereby increasing the risk of data leakage and abuse. The trusted execution environment represented by software guard extension (SGX) provides new ideas for trusted execution of IoT data trading based on smart contracts. SGXs is a set of hardware security enhancement technologies launched by Intel, which aims to protect the execution of sensitive data and code through the hardware isolation and security encryption capabilities provided by the processor. However, we found that due to SGX’s lack of a checksum mechanism for the execution state of smart contracts, a rollback attack can lead to errors when the account state of IoT data trading is replayed. To address the above issues, we propose a trusted execution environment for IoT data trading with rollback protection. First, we design a freshness checking mechanism for the execution state of IoT data trading contracts for rollback protection. In addition, we propose a “chain-of-trust”-based authentication model to realize trust metrics and remote proofs for the proposed trusted execution environment for IoT data trading. Finally, we then provide a formal security analysis and comprehensive performance evaluation.

The Internet of Things (IoT) is a network composed of information-gathering devices, sensors, and computing devices assembled in an intelligent manner, and the most important element in this system is data. IoT data trading plays a vital role in the area of personalized business nowadays. Individual IoT devices generate large amounts of private data, which data owners can sell to enterprises as important digital assets to make money, while enterprises collect IoT data to improve the accuracy of their services. Cloud storage services have been widely used in IoT data trading. In IoT data trading, cloud storage services have been widely used for individuals to store IoT data and for enterprises to automatically facilitate data trading. However, there are still two crucial drawbacks to be solved. From the point of security, it is difficult for data buyers to check the validity of the search result without getting the decryption key of the data owner. From the point of fairness, there is a lack of a punishment mechanism to transfer money from the cheating party to the honest party. To tackle the two challenges, we propose a searchable re-encryption scheme to maintain traditional security without sacrificing service quality. Next, we design a fair trading protocol based on smart contracts to automatically detect any cheating behaviors. Formal security analysis proves that the scheme provides expected security. Experimental results show that the scheme achieve good performance.

Federated learning is a distributed machine learning approach that enables multiple participants to collaboratively train a model without sharing their data, thus preserving privacy. However, the decentralized nature of federated learning also makes it susceptible to backdoor attacks, where malicious participants can embed hidden vulnerabilities within the model. Addressing these threats efficiently and effectively is crucial, especially given the impracticality of iterative and resource-intensive detection methods in federated learning environments. This article presents a novel framework for one-shot backdoor removal in federated learning. Our approach integrates advanced anomaly detection techniques with a unique model update aggregation strategy, allowing for the identification and neutralization of backdoor influences in a single update cycle without the need for extensive data access or communication between participants. Extensive experiments across various federated architectures and data distributions demonstrate that our method effectively mitigates backdoor threats while maintaining model performance and scalability. This work not only enhances the security of federated models but also contributes to the broader applicability of federated learning in sensitive and critical domains.

With the proliferation of IoT devices today, the need to strengthen the security of these devices is becoming increasingly urgent, particularly the need to review the security of lightweight block ciphers. SIMON is a lightweight block cipher proposed by the National Security Agency (NSA) of US to provide efficient and secure encryption for resource-constrained devices in IoT systems. This paper aims to evaluate the security of SIMON against mixture differential cryptanalysis, which was proposed in Eurocrypt 2017 to launch the best key-recovery attacks on the most widely used encryption standard AES. Though there have been intensive studies on this cryptanalysis method, its current targets are all aligned block ciphers. Whether the numerous bitwise block ciphers, including SIMON, have weaknesses regarding this method remains unknown. In this paper, we extend the mixture differential cryptanalysis to bit-wise ciphers and develop an SAT-based automatic tool to search for such distinguishers. We interpret the bit-wise mixture differential distinguisher as a variant of differential distinguisher in the multi-key setting with 2-3n as the boundary (n:block size), potentially boosting rounds or improving the signal-to-noise ratio of previous boomerang or classical differential distinguisher. Using SIMON as an example, we discover multi-key distinguishers for up to 17-round SIMON32, 18-round SIMON48, and 23-round SIMON64, which outperform previous results in terms of the number of rounds. This paper reconciles the disparity between mixture differential cryptanalysis applied to word-oriented target ciphers and its application to bit-oriented targets, thereby extending the mixture differential cryptanalysis to a broader range of block ciphers.

The novel sensing paradigm known as crowdsensing leverages ubiquitous smart devices to collect data in Internet of Things (IoT) applications. Traditional crowdsensing schemes assume a central framework to execute truth discovery algorithm to assure data quality, which may introduce reliability and privacy issues. Blockchain is a promising technology that provides a decentralized, transparent, and immutable platform. However, designing a blockchain-based quality assurance scheme in crowdsensing is not a trivial problem. First, truth discovery is a time-consuming iterative algorithm, which is not practical to execute on blockchain. Second, privacy-preserving schemes always require that the participants join in multiround communications, which is not acceptable in open blockchain because of users’ highly unpredictable behaviors. Finally, on-chain data are publicly accessible, and achieving a good balance between data utility and privacy is an important issue. In this article, we propose a lightweight quality assurance framework atop blockchain to build a reliable, privacy preserving, and fair crowdsensing system. Specifically, we carefully design two kinds of smart contracts to cooperatively maintain a long-term reliable platform to execute crowdsensing tasks. In the contracts, we devise a reputation-based aggregator selection algorithm to reach the consensus on truthful results while avoiding expensive on-chain iterative processes. The participant selection scheme and reward policy are further utilized to filter appropriate participants to complete the task. Our scheme also protects data privacy and does not require communications between participants. Finally, we implement and deploy the contracts on Ethereum and conduct extensive experiments to demonstrate that the contracts can practically execute crowdsensing tasks.

In this article, we propose a secure fine-grained task allocation scheme with bilateral access control (FTA-BAC) for intelligent transportation systems. To enhance the security, we formulate bilateral access control in task allocation, by adopting the matchmaking encryption (ME) to encrypt the task requirements/interests for secure task matching. In this way, both task requesters and workers can specify their match policies simultaneously, without revealing their sensitive information (i.e., attributes and geographical location). To realize fine-grained task allocation, we use a linear integer secret sharing (LISS) scheme to represent task requirements/interests, supporting theAND/ORoperation on match policies. To further improve the efficiency, we design a delegation mechanism to reduce the computation burden on resource-limited end devices, by diverting the high-frequency matching operations to edge nodes. Then, we prove the security of FTA-BAC under formally defined security model. Finally, we analyze the performance of FTA-BAC through theoretical analysis and experimental evaluation, demonstrating that FTA-BAC can provide practical task allocation for intelligent transportation systems compared with the state-of-the-art works.

With the help of artificial intelligence, the large amount of data generated by Internet of Things (IoT) has unleashed significant value. Federated learning is emerging as a novel paradigm which can be applied to solve the privacy issues caused by analyzing IoT data. However, traditional federated learning protocols are vulnerable to inference and poisoning attacks. Various solutions have been proposed to enhance data privacy and robustness. Nonetheless, most of these solutions are usually centralized and rely on unrealistic security assumptions. Furthermore, the recently proposed blockchain-based decentralized solutions generally incur high costs, which is unaffordable for resource-constrained IoT devices. In this article, we propose a practical secure federated learning system named PrSeFL. We utilize blockchain to decentralize the federated learning process so that the security assumptions are easier to achieve in practice. To preserve data privacy, we implement secure multiparty computation-based secure aggregation in blockchain environment. To guarantee practical robustness, we enforce norm constraints on the masked updates via zero-knowledge proof. Moreover, we propose a modified dynamic accumulator which is utilized to realize lightweight anonymous authentication of users. Simulation results show that, compared with state-of-the-art systems, PrSeFL has superior performance on authentication and model training. And the advantage of PrSeFL becomes more significant as the number of users grows.

Ethereum is the second-largest blockchain platform, and the financial value of its cryptocurrency has constantly increased. Unfortunately, regulatory challenges have resulted in a surge of scams, particularly phishing, which now accounts for over 50% of fraudulent funds. Therefore, phishing scam issues have become a top priority, thus calling for dynamic early warning and accurate identification to achieve effective market regulation. However, the existing works focusing on phishing address detection do not consider early warnings for phishing scams. Furthermore, these methods depend on static graphs to extract node information and overlook the dynamic evolution process of the Ethereum network. In this article, we propose EWDPS, a novel framework to achieve dynamic early warning and effectively identify phishing scams on Ethereum. Specifically, we create a new network called the dynamic temporal transaction network (DTTN), which effectively models the dynamic temporal evolution of transactions. In DTTN, we propose the concepts of temporal evolution interaction network and account feature interaction network. Next, we design a novel feature extraction module to capture temporal sequential patterns effectively. This module takes full advantage of the dynamic interaction process of node-related transactions. Finally, we innovatively use the extracted account, network, and temporal features to enhance transaction representation in multiple dimensions. Extensive experiments show that our proposed scheme effectively achieves dynamic early warning and accurately identifies phishing scams. EWDPS achieves 92.20% accuracy, 95.90% precision, 96.77% recall, and 96.53% F1-score, and outperforms the state-of-the-art methods in phishing address identification.

Owing to its practical configuration to edge computing and privacy preservation capabilities, federated learning (FL) has been increasingly appealing in Internet of Things (IoT) networks. However, due to the inherent openness of IoT network architectures, FL clients are susceptible to various attacks, resulting in unreliable local model updates. To address this challenge, federated unlearning (FU) emerges as a viable solution, which can erase such unreliable updates from the FL model using the unlearning operation while preserving model accuracy. Existing FU studies have significant potential, but they are not directly applicable to IoT networks because of their high computational costs and limited capacity to defend against prevalent dynamic attacks in mobile network environments. In this work, we propose FedRemover, a novel FU method specifically tailored for deployment in IoT networks. The key insight behind FedRemover is that model updates will exhibit inconsistency when exposed to attacks. Therefore, we devise a real-time malicious client detection scheme by examining the performance consistency of model updates. Upon detecting malicious clients, FedRemover promptly executes the unlearning operation, achieving an unlearned global model within a minimal number of rounds. This makes FedRemover highly efficient and robust against dynamic attacks, enabling it well-suited for practical deployment in IoT networks. Experiments on three standard datasets demonstrate the efficiency and robustness of FedRemover, with an obvious speed-up of 10× and comparable robustness guarantees compared with benchmark algorithms.

For increasing Internet of Things (IoT) devices, 6G wireless technology aims for ubiquitous communications in which positioning services are necessary. Private spatial keyword-based positioning service is promising in 6G-oriented IoT since it positions users based on spatial locations and textual keywords while protecting user privacy. However, due to economic benefits or malicious attacks, positioning service providers may return erroneous or incomplete results, which cause tremendous economic damage and security threats, e.g., always assigning a selective driver for the specific car-hailing user. A technical challenge for extending existing private schemes to enable users to verify the correctness and completeness of positioning results is the distinctive positioning paradigm between compared spatial locations and matched textual keywords. This paper proposes a private and verifiable spatial keyword positioning scheme named VSpatial in 6G-oriented IoT. VSpatial enables users to verify the correctness and completeness of spatial keyword-based positioning results while preserving user privacy. The main inspiration for addressing the technical challenge is converting both spatial locations and textual keywords into an internal status, i.e., adapting comparison and matching to existence judging by multiple cryptographic tools, such as hierarchical cube and pseudorandom function. Based on this inspiration, we design a novel private authenticated data structure (named PVTree), and then propose two constructions of VSpatial, i.e., VSpatial-S and VSpatial-D, to suit static and dynamic environments, respectively. The core idea for adapting VSpatial-S to VSpatial-D is transferring one whole PVTree into multiple exponential-size partitions. Security analysis proves the security and verifiability of VSpatial. Theoretical and experimental evaluations show that VSpatial achieves faster-than-linear positioning efficiency and linear verification overhead.

Metaverse provides human-centric immersive communication experiences where humans can teleport across different virtual landscapes and build real-time communications via digital identities with others in the same landscape. Despite great benefits, a natural question in human-centric metaverse communications is how to secure digital content among humans. In this regard, blockchain has been widely applied due to its distinct features (e.g., decentralization, transparency, and immutability). Unfortunately, the inherent properties of the blockchain also hinder humans from further deploying preferences to flexibly govern the digital content (i.e., who can read and who can edit), limiting human-centric communication abilities. Some redactable blockchain-based solutions have been proposed, but most of them suffer from the issues of data and preference leakage. To address the issues, we propose a privacy-preserving identity-based data governance (IDRG) scheme for blockchain-empowered human-centric metaverse communications. Combining digital identities, IDRG cryptographically allows humans to govern readability and editability with the right downward compatibility (i.e., humans with editability are endowed with readability) while protecting policy privacy. Specifically, IDRG leverages the polynomial function technique to break through the bottleneck of the traditional identity-based encryption technique (i.e., a policy only contains a user) to achieve a policy for multiple users. Subsequently, the optimized policies are utilized to enrich chameleon hash-based redactable blockchains for comprehensive rights governance. Further, IDRG supports user accountability and revocation by combining the proxy re-encryption technique. Security analysis proves the security of IDRG under the chosen-ciphertext attack. Experiments on the FISCO blockchain platform demonstrate that IDRG requires approximately 0.1 s to process an encryption request, 0.01 s for a reading request, and 1 s for an editing request. Overall, IDRG achieves a$3\times $reduction in computational costs compared with state-of-the-art solutions.

Sentiment Quantification aims to detect the overall sentiment polarity of users from a set of reviews corresponding to a target. Existing methods equally treat and aggregate individual reviews' sentiment to judge the overall sentiment polarity. However, the confidence of each review is not equal in sentiment quantification where sentiment perturbation arising from high- and low-confidence reviews may degrade the accuracy of Sentiment Quantification. Specifically, fake reviews with deceptive sentiments are low confidence, which perturbs the overall sentiment prediction. Whereas, some reviews generated by responsible users are high confidence. They contain authoritative suggestions so they should be emphasized in Sentiment Quantification. In this paper, we design and build COSE, a confidence-aware sentiment quantification framework, which can measure the confidence of individual reviews to eliminate sentiment perturbation and facilitate sentiment quantification. We design a Review Graph that achieves review confidence modeling in an unsupervised manner and obtains review confidence representations. Moreover, we develop a dynamic fusion attention mechanism, which produces sentiment “de-perturbation” vectors to eliminate the sentiment perturbation based on the confidence representations. Extensive experiments on large-scale review datasets validate the significant superiority of COSE over the state-of-the-art.

Decentralized identity (DID) systems conforming to the World Wide Web Consortium (W3C) Decentralized Identifiers (DIDs) and Verifiable Credentials Data Model recommendations have recently attracted attention due to their better autonomy, interoperability, and openness design. However, those W3C recommendations lack a design for addressing the single point of failure (SPOF) and identity revocation, which could seriously compromise the robustness and practicality of DID systems. To remedy these limitations, we propose FutureDID, a DID system that enables multiple parties to jointly issue credentials and efficiently revoke DID identities, providing a robust and practical DID system. FutureDID is designed with a multi-party credential issuing mechanism based on distributed key generation technology, which transforms trust from a single entity to distributed committees and facilitates authentication between issuers, making it more resistant to SPOF. Moreover, the underlying blockchain system is built on a chameleon hash function to ensure tamper-proof and enable efficient identity revocation. We have implemented a prototype system using FISCO BCOS and conducted extensive evaluations to demonstrate the effectiveness and practicality of our system. Our evaluations have shown that FutureDID provides a significant improvement in efficiency, achieving at least a 60 × efficiency improvement in identity revocation compared to state-of-the-art systems.

Data deduplication and integrity auditing based blockchain plays an important role in guaranteeing secure and efficient cloud storage services. However, existing data deduplication schemes support auditing either with the assistance of a trust center (key server or third-party auditor) or bear the waste of computation and storage resources caused by repetitive authenticators storage and key storage. In this paper, we propose a blockchain-based shared data integrity auditing and deduplication scheme. Specifically, we propose a deduplication protocol based on ID-based broadcast encryption without key servers and achieve key deduplication on the user side. Next, we propose a data integrity auditing protocol by using the characteristic of convergent encryption to achieve authenticator deduplication on the cloud service provider side. Besides, we achieve decentralized data integrity auditing based blockchain without relying on a single trusted third-party auditor and improve the credibility of the auditing result. On this basis, we propose two bath auditing protocols for different scenarios to improve efficiency. Security and performance analysis demonstrates that the authenticators' storage cost on the cloud storage provider side can be reduced from${\mathcal {O}}({\mathcal {F}})$to${\mathcal {O}}(1)$and the key storage cost on the user side can be reduced from${\mathcal {O}}({\mathcal {F}})$to${\mathcal {O}}(1)$as well.

Decision-based adversarial attacks pose a severe threat to real-world applications of Deep Neural Networks (DNNs), as attackers are assumed to have no prior knowledge about target model except hard labels of model outputs. Existing decision-based attacks require a large number of queries on the target model for a successful attack. In this paper, we propose DEAL, a decision-based query efficient adversarial attack based on adaptive boundary learning. DEAL relies on a local model named boundary learner, which is initialized through meta-learning mechanism to obtain the ability to adapt the decision boundaries to a new model. We conduct extensive experiments to evaluate the effectiveness of DEAL, which demonstrates that it outperforms 8 state-of-the-art attacks. Specifically for the evaluation on CIFAR-10 dataset, DEAL can achieve similar attack success rates with a maximum reduction in average number of queries of 51% in untargeted attacks and 14% in targeted attacks, respectively.

The sealed-bid auction enables bidders to secretly send their bids to the auctioneer, which compares all bids and publishes the winning one on the bid-opening day. This type of auction is friendly for protecting the bid privacy, and sufficiently fair for all bidders if the auctioneer acts faithfully. Unfortunately, the auctioneer may not always be trustworthy. The auctioneer has the ability to deliberately leak any bid information to a part of bidders for raising the final winning price based on the investigation. Meanwhile, the auctioneer can appoint any bidder as the winner, as long as the bidder accepts a higher winning price than the current highest bid. Since bidders cannot obtain any bid information from others, to the best of our knowledge, it is difficult to prevent bid leakage from the auctioneer, and support bidders to verify the bid comparison results without disclosing the winning bid, simultaneously. To alleviate these problems, we first construct a homomorphic encryption(HE)-based bid comparison circuit. All bidders can directly compute a cipher of the winning bid by using this circuit; hence, the winning bid does not need to be exposed to all bidders. Then, we propose a blockchain-based sealed-bid scheme (BSS) by integrating the circuit with commitment and zero-knowledge proof. The auctioneer only obtains the commitments of bids before the bid-opening day, and he has to prove that the winner's bid is the same as the plaintext of the bidders' computed cipher. Thus, the auctioneer can neither leak the bid information nor publish a higher winning price during in the auction. Detailed performance analysis shows that the computational complexity of BSS is linear with the binary length of bids.

In the context of consortium blockchain, consensus protocols set permission mechanisms to maintain a relatively fixed group of participants. They can easily use distributed consistent algorithms for achieving deterministic and efficient consensus and generate incessant blocks as the ledger. However, most of the existing consensus protocols do not sufficiently leverage the chain structure of blocks, and therefore leaving room for performance improvement. In this paper, we first propose a Hashchain-based Consensus Acceleration (HCA) protocol. The HCA protocol enables a leader to generate blocks that contain a quorum of votes on the previous block, and allow voters to re-vote for accelerating the block generation to Byzantine Fault Tolerance (BFT) consensus protocols. Then, we present a rolling-based leader selection (RLS) scheme to further optimize the HCA protocol. In the RLS scheme, the leader is changed in a round-robin fashion. Finally, theoretical analysis proves the safety, liveness and responsiveness of the optimized HCA protocol, while experimental evaluation shows that the optimized HCA protocol outperforms the existing BFT consensus protocols, from the viewpoint of efficiency.

Recently, increasing personal data has been stored in blockchain databases, ensuring data integrity by consensus. Although transparent and immutable blockchains are mainly adopted, the need to deploy preferences on which users canreadandeditthe data is growing in importance. Based on chameleon hashes, recent blockchains support editability governance but can hardly prevent data breaches because the data is readable to all participants in plaintexts. This motivates us to propose NANO, the first permissioned blockchain database that provides downward compatible readability and editability governance (i.e., users who caneditthe data can alsoreadthe data). Two challenges are protecting policy privacy and efficiently revoking malicious users (e.g., users who abuse their editability privileges). The punchline is leveraging Newton's interpolation formula-based secret sharing to hide policies into polynomial parameters and govern the distribution of data decryption keys and chameleon hash trapdoors. Inspired by proxy re-encryption, NANO integrates unique user symbols into user keys, achieving linear user revocation overhead. Security analysis proves that NANO provides comprehensive privacy preservation under the chosen-ciphertext attack. Experiments on the FISCO blockchain platform demonstrate that compared with state-of-the-art related solutions, NANO achieves a 7× improvement on average regarding computational costs, gas consumption, and communication overhead.

The offloading of computation-intensive tasks to an edge server near resource-constrained mobile devices can provide improved application performance and user experience. However, with the rapid growth of mobile devices connected to the edge server, it is challenging to directly obtain an optimal task offloading scheme due to increasing computational cost and problem scale. In this study, we model the costly task offloading problem (CTOP) in mobile edge computing networks to achieve efficient joint optimization of energy consumption and processing latency for mobile devices. Inspired by the success of evolutionary multitasking in solving complex optimization problems by leveraging the experience of simple optimization problems, we develop a novel multitasking framework whose effectiveness is demonstrated in solving the CTOP. In this framework, auxiliary tasks are created to optimize the local processing overhead and the edge processing overhead of task offloading. On this basis, we propose an effective multitask evolutionary algorithm that includes segmented knowledge transfer and auxiliary task update. Specifically, source and extended decision variables are considered as different knowledge to be utilized, while the auxiliary tasks are allowed to be updated dynamically. Related knowledge that is learned from cheap and simple auxiliary tasks promotes the evolutionary search for CTOP. Experimental results verify the effectiveness of knowledge transfer. Compared to existing multitasking and single-tasking algorithms, the proposed algorithm shows competitive performance in CTOP instances and achieves better comprehensive performance in terms of energy consumption and processing latency.

Blockchain-based censorship-resistant systems enable the user to access the blocked content through a covert channel while avoiding a suspicious network connection between the user and the proxy. However, state-of-the-art blockchain-based censorship-resistant schemes cannot satisfy both low communication fees and unobservability, and their method of identifying transactions with covert data may inadvertently expose the covert channel. In this paper, we present Hades, a blockchain-based covert channel framework that aims to circumvent censorship. Hades allows users to encode covert data as a transaction field, and identify transactions with covert data by using another transaction field as a label. We also present the security model for Hades, which defines the unobservability of Hades as the indistinguishability of transactions with covert data from normal transactions. We further propose two cost-friendly and unobservable instantiations of Hades: the basic RDSAC and the improved DDSAC. RDSAC uses private keys to encode covert data and utilizes random factors in the signing process as labels, while incurring a communication delay. DDSAC avoids the delay by encoding covert data into random factors and sampling a transaction amount from normal transactions as the label. We implement a prototype system of Hades and evaluate its performance. Experiment results show that our Hades prototype is unobservable, robust, and efficient. RDSAC and DDSAC can identify 1,654 transactions in 6.054 seconds and 0.071 seconds, respectively. Hades supports 1KB data transfer at $0.44 on the Bitcoin mainnet and cost-free data transfer on the Bitcoin testnet.

Covert channels in blockchain networks achieve undetectable and reliable communication, while transactions incorporating secret data are perpetually stored on the chain, thereby leaving the secret data continuously susceptible to extraction. MTMM (IEEE Transactions on Computers 2023) is a state-of-the-art blockchain-based covert channel. It utilizes Bitcoin network traffic that will not be recorded on the chain to embed data, thus mitigating the above issues. However, we identify a distinctive pattern in MTMM, based on which we propose a comparison attack to accurately detect MTMM traffic. To defend against the attack, we present an improvement named ORIM, which exploits the permutation of transaction hashes within inventory messages to transmit secret data. ORIM leverages a pseudo-random function to obscure the transaction hashes involved in the permutation to ensure unobservability. The obfuscated values, rather than the original transaction hashes, are utilized to encode the confidential data. Furthermore, we introduce a variable-length encoding scheme predicated on complete binary trees. This scheme considerably amplifies the bandwidth and facilitates efficient encoding and decoding of secret data. Experimental results indicate that ORIM maintains unobservability and that ORIM’s bandwidth is approximately$3.7\times $of MTMM.

With the property of helping users further enhance the anonymity of transactions, mixing services in blockchain have gained wide popularity in recent years. However, the strong untraceability offered by mixing services has led to the abuse of them by criminals for money laundering and committing fraud. These illegal actions pose significant threats to the blockchain ecosystem and financial order. In this paper, we focus on the problem of correlating the addresses of mixing transactions in Tornado Cash, a widely-used mixing service on Ethereum. We propose a graph neural network framework named MixBroker, which aims to break the anonymity of Tornado Cash by correlate mixing addresses from the perspective of node-pair link prediction. Specifically, we construct a Mixing Interaction Graph (MIG) using raw Ethereum mixing transaction data that can be used for subsequent analysis. To better represent the properties of mixing account nodes, we extract features from account nodes in the MIG from multiple perspectives. Furthermore, we design a GNN-based link prediction mechanism to serve as the backbone of MixBroker. This mechanism captures the interconnected nature of nodes within the MIG and calculates the probability of correlation between account nodes through node embeddings. In addition, to solve the problem of lacking ground-truth, we collect a large number of real mixing transactions of Ethereum in Tornado Cash and construct a ground-truth dataset by combining the principles of Ethereum Name Service (ENS). We conduct extensive experiments on the datasets, and the results demonstrate that MixBroker has a superior performance over other state-of-the-art methods on the address correlation problem in Ethereum mixing transactions.

Covert communication is an method that plays an important role in secure data transmission. The technology embeds covert information into data and propagates it through covert channels. The communication quality depends on the choice of channel and data embedding techniques. Recently, blockchain has emerged to become the preferred channel to carry out covert communication for its decentralization and anonymity features. Existing covert transaction methods are constructed transaction-by-transaction, which makes them immune to text analysis-based detection methods. However, it is easy to expose their features on the transaction graph level. Unfortunately, there is yet no method to detect covert transactions by the features of transaction graph. In this paper, we propose a covert transaction detection method based on graph structure. By analyzing the statistical features of graph structure for addresses, we can infer whether they are the participants of covert transactions. Furthermore, we design a protection method of covert transactions based on graph generation networks. By adjusting the structural features between different addresses, our method enhances the security of multiple interrelated covert transactions. Experimental analysis on the Bitcoin Testnet verifies the security and the efficiency of the proposed methods.

Cryptographic access control guarantees that authorized users can access data while unauthorized get nothing. Such an all-or-nothing access mode achieves secrecy but does not fit strong-privacy scenarios. FE-based access control breaks it and reaches a balance between data privacy and data utilization. To resist malicious senders, Damgard et al. introduced sanitizable functional encryption that enables a bi-directional control to both senders and receivers. However, its centralized structure means that the compromise of the authority incurs massive secret leakage and undermines the system’s reliability. In this work, we present SanIdea, a sanitizable, decentralized and privacy-preserving access control framework which embraces a sanitizer in the distributed-authority-domain access control setting. We instantiate it by proposing a cryptographic primitive named sMABE, which adds a$\mathsf {Sanitize}$algorithm over multi-authority attribute-based encryption. We formally prove its security in the IND-CPA model and the Sanitization Security model under the DBDH assumption. We demonstrate its reasonable efficiency through algorithm simulation, where the sanitization time is less than 0.1s with the configuration of 5 attribute authorities and 25 user attributes. We design an SABC system by integrating SanIdea with the blockchain, where SABC uses a smart contract to ensure the correctness of the distributed secret key parts. We implement SABC in an Ethereum testbed and the experiment results show that the$\mathsf {upload}$algorithm costs about 163000 user gas and the$\mathsf {download}$algorithm costs about 84000 user gas, which is cost-reasonable.

Access control encryption enables access control on both senders and receivers, and enhances message sanitization compared with traditionally cryptographic access control mechanisms. However, it is usually built on top of encrypted messages, which makes it difficult to identify malicious data and amplifies abusive message transmission. The message franking and source tracing mechanisms facilitate a report of abusive messages while support only plain-data moderation in end-to-end encryption. In this work, we present sMAC, a sanitizable and moderate access control framework which supports both sanitization and moderation over the encrypted messages as well as the data privacy, sender anonymity and backward security. We instantiate it by proposing a cryptographic primitive named amenable ACE, which expands the message accountability algorithm module in addition to access control encryption. We give formal security proof of amenable ACE in the standard model. The experimental results show that amenable ACE is efficient where the computational cost of Decrypt, Stamp, Verify and Inspect is independent of the message size.

Cross-chain systems provide a way for isolated blockchains to communicate and exchange assets and data with each other. Sidechain-based cross-chain systems support more scenarios with more complicated functionalities. However, the correlation of transactions in two underlying blockchains makes the linkability for the sidechain and exposes the identity of transaction parties and transaction amounts. This incurs the cross-chain privacy leakage. Traditional privacy-preserving mechanisms conversely compromise the regulation of transactions, which limits the identification and punishment to malicious transaction parties. To balance privacy and regulation of cross-chain systems, in this paper, we propose PCP, a privacy-preserving policy-enforcement cross-chain protocol between Monero and Bitcoin. It leverages the signature of knowledge to guarantee the correctness and privacy, while sets a trapdoor for tracing authority to revoke the anonymity when the investigation is required. We instantiate a scheme with formal security proof. We conduct a series of experiments by using Fiat-Shamir paradigm with zero-knowledge and the results show that the proposed PCP is cost-reasonable with constant 150 ms for Swap Monero phase, 40 ms for proof generation and 24 ms for proof verification.

Threshold signature is a fundamental cryptographic primitive used in many practical applications. As proposed by Boneh and Komlo (CRYPTO’22), TAPS is a threshold signature that is a hybrid of privacy and accountability. It enables a combiner to combine$t$signature shares while revealing nothing about the threshold$t$or signing quorum to the public and asks a tracer to track a signature to the quorum that generates it. However, TAPS has three disadvantages: it 1) structures upon a centralized model, 2) assumes that both combiner and tracer are honest, and 3) leaves the tracing unnotarized and static. In this work, we introduce Decentralized, Threshold, dynamically Accountable and Private Signature (DeTAPS) that provides decentralized combining and tracing, enhanced privacy against untrusted combiners (tracers), and notarized and dynamic tracing. Specifically, we adopt Dynamic Threshold Public-Key Encryption (DTPKE) to dynamically notarize the tracing process, design non-interactive zero knowledge proofs to achieve public verifiability of notaries, and utilize the Key-Aggregate Searchable Encryption to bridge TAPS and DTPKE so as to awaken the notaries securely and efficiently. In addition, we formalize the definitions and security requirements for DeTAPS. Then we present a concrete construction and formally prove its security and privacy. To evaluate the performance, we build a prototype based on SGX2 and Ethereum.

Internet of Medical Things (IoMT) technology has gained a lot of attention. In the IoMT system, IoT devices collect and upload patient data through sensors, and doctors treat them remotely. In this process, doctors need to verify the correctness of the patient’s body data in bulk, a function that requires aggregated signature technology to achieve. However, due to the limitation that traditional verification of aggregated signatures requires access to all messages, doctors cannot efficiently verify the correctness of a particular piece of data. This will result in a significant additional verification overhead. Therefore, the efficiency problem of data batch authentication remains unsolved but imperative. In this paper, we propose an identity-based locally verifiable aggregated signature, (ID-LVEAS), that enables efficient local verification of patient data in IoMT. Building on top of both hybrid hash and inverse framework, we instantiate an ID-LVEAS scheme and prove its security in the EU-CMA security model. Based on ID-LVEAS, we further propose ID-based locally verifiable signcryption (ID-LVASC) that supports both confidentiality and integrity. We also present an instantiation and an application into IoMT from the proposed ID-LVASC. We conduct extensive experiments on the ID-LVEAS and ID-LVASC design. The results show that both cost constantly 0.01s for the verification, independent of the number of messages, which means our research has great promise for application in IoMT.

Deep neural networks (DNNs) are vulnerable to adversarial examples, with transfer attacks in black-box scenarios posing a severe real-world threat. Adversarial perturbation is often globally manipulated image disturbances crafted in the spatial domain, leading to perceptible noise due to overfitting to the source model. Both the human visual system (HVS) and DNNs (endeavoring to mimic HVS behavior) exhibit unequal sensitivity to different frequency components of an image. In this paper, we intend to exploit this characteristic to create frequency-aware perturbation. Concentrating adversarial perturbations on components within images that contribute more significantly to model inference to enhance the performance of transfer attacks. We devise a systematic approach to select and constrain adversarial optimization in a subset of frequency components that are more critical to model prediction. Specifically, we measure the contributions of each individual frequency component and devise a scheme to concentrate adversarial optimization on these important frequency components, thereby creating frequency-aware perturbations. Our approach confines perturbations within model-agnostic critical frequency components, significantly reducing overfitting to the source model. Our approach can be seamlessly integrated with existing state-of-the-art attacks. Experiments demonstrate that while concentrating perturbation within selected frequency components yields a smaller perturbation magnitude overall, our approach does not sacrifice adversarial effectiveness. Conversely, our frequency-aware perturbation manifests superior performance, boosting imperceptibility, transferability, and evasion against various defenses.

In side-channel testing, the standard timing analysis works when the vendor can provide a measurement to indicate the execution time of cryptographic algorithms. In this paper, we find that there exists timing leakage in power/electromagnetic channels, which is often ignored in traditional timing analysis. Hence a new method of timing analysis is proposed to deal with the case where execution time is not available. Different execution time leads to different execution intervals, affecting the locations of plaintext and ciphertext transmission. Our method detects timing leakage by studying changes in plaintext-ciphertext correlation when traces are aligned forward and backward. Experiments are then carried out on different cryptographic devices. Furthermore, we propose an improved timing analysis framework which gives appropriate methods for different scenarios.

Threshold signatures as a method to realize multi-party cooperation and trust distribution in blockchain have been widely studied in recent years. However, among these researches, few threshold signature schemes achieve all the properties of accountability, privacy, and key protection for the EdDSA-based blockchain systems. To fill this gap, we propose an EdDSA-based accountable threshold signature protocol with privacy and proactive refresh, named TAPS-PR. Meanwhile, we define new security models and give a detailed analysis to prove protocol security. In TAPS-PR, the threshold is variable and hidden with the signing quorum from the public view. However, the signing quorum can be traced when threshold signatures related to fraudulent events are generated. We also enhance the key security of each signer by proactive refresh, which realizes updating the private key while the public key remains unchanged. Apart from that, we present ATS-PR with increased efficiency and reduced communication cost at the cost of weaker security. The theoretical analysis and experimental results indicate that our protocols perform efficiently in terms of communication and computation overhead. Furthermore, we use Tezos, a blockchain project employing EdDSA, as a case study to demonstrate the compatibility of our protocol with real-world blockchain applications.

Outsourcing storage has emerged as an effective solution to manage the increasing volume of data. With the popularity of pay-as-you-go payment models in outsourcing storage, data auditing schemes that prioritize timeliness can be valuable evidence for elastic bill settlement. Unfortunately, existing data auditing schemes do not sufficiently consider timeliness during auditing. Furthermore, practical data auditing schemes should have the capability to check the integrity of scalable data. In this paper, we propose a blockchain-based dynamic data auditing scheme with strong timeliness to ensure that data stored in outsourcing storage systems remain intact. Our scheme encapsulates timestamps into homomorphic verifiable tags to simultaneously check data integrity and timestamp validity. To achieve dynamicity, we utilize the Merkle hash tree to store the tags, allowing for block-level dynamic operations. Additionally, by leveraging the transparency, non-repudiation, and tamper resistance of blockchain technology, we design a blockchain-based data auditing framework to prevent malicious behavior from all entities. We then formally prove the soundness and privacy of our scheme. Finally, we conduct theoretical analysis and experimental evaluation to demonstrate that the performance of our scheme is of acceptable efficiency to existing works in terms of computation cost, communication overhead, and storage overhead.

In this paper, we propose a revocable and privacy-preserving bilateral access control scheme (named PriBAC) for general cloud data sharing (i.e., end-cloud-based data sharing). PriBAC ensures that preference matching is successful only when both parties’ preferences are satisfied simultaneously. Otherwise, nothing is leaked beyond whether the preference matching occurs. There are three challenges in designing PriBAC. The first challenge is protecting matching information, i.e., concealing two preference matching processes, in a single cloud server. The second challenge is protecting preference content while preventing receivers from receiving much useless information. The third challenge is how to integrate efficient user revocation mechanisms into bilateral access control to handle frequent user revocation cases in practical cloud data sharing applications. To address the above challenges, the punchline in PriBAC is to leverage Newton’s interpolation formula-based secret sharing to enrich the matchmaking encryption technique for constructing a privacy-preserving preference matching mechanism. To achieve efficient user revocation, we integrate a unique symbol into each user’s keys and efficiently revoke users by invaliding the corresponding keys. Security analysis proves that PriBAC can resist the chosen-ciphertext attack and preserves preference privacy and matching privacy. Experiments show that PriBAC achieves approximately$3\times $user performance improvement compared with current state-of-the-art related schemes.

Blockchain is a revolutionary technology for constructing trustworthy communications for 6G multiaccess edge computing (6G-MEC). Designing a blockchain-based access control system for 6G-MEC is challenging due to the highly heterogeneous edge devices (EDs) in 6G-MEC. However, traditional blockchain-based access control methods cannot satisfy the heterogeneous device scenarios and are unable to assign voting weights based on the performance of EDs. In this article, we propose a trustworthy access control method for 6G-MEC networks and demonstrate how blockchain can be utilized in our proposed blockchain-assisted multiaccess control approach. Our approach develops an attribute validation and a validation weight method to offer strengthened access control in a decentralized context. We have proposed a trustworthy access control for multiaccess edge computing by using a multitier blockchain architecture and a reinforcement-learning-based weight determination algorithm for ED to eliminate the influence on blockchain consensus behavior. Experimental results demonstrate the effectiveness of our proposed approach.

Digital forensics is crucial to fight crimes around the world. Decentralized Digital Forensics (DDF) promotes it to another level by channeling the power of blockchain into digital investigations. In this work, we focus on the privacy and security of DDF. Our motivations arise from (1) how to track an anonymous-and-malicious data user who leaks only a part of the previously requested data, (2) how to achieve access control while protecting data from untrusted data centers, and (3) how to enable efficient and secure search on the blockchain. To address these issues, we propose Themis: an anonymous and secure DDF scheme with traceable anonymity, private access control, and efficient search. Our framework is boosted by establishing a Trusted Execution Environment in each authority (blockchain node) for securing the uploading, requesting, and searching. To instantiate the framework, we design a secure and robust watermarking scheme in conjunction with decentralized anonymous authentication, a private and fine-grained access control scheme, and an efficient and secure search scheme based on a dynamically updated data structure. We formally define and prove the privacy and security of Themis. We build a prototype with Ethereum and Intel SGX2 to evaluate its performance, which supports processing data from a considerable number of data providers and investigators.

Federated Learning (FL)has achieved state-of-the-art performance in training a global model in a decentralized and privacy-preserving manner. Many recent works have demonstrated that incentive mechanism is of paramount importance for the success of FL. Existing incentives to FL either neglect communication efficiency, or consider communication efficiency but design the incentive mechanisms using non-cooperative games under complete information assumption, or study incentive mechanism under incomplete information but only apply to the sequential interaction setting. We shed light on this problem from the cooperative perspective and propose an incentive mechanism for communication-efficient FL based on the Nash bargaining theory. Specially, we formulate our incentive mechanism as a one-to-manyconcurrent bargaininggame among the aggregator and clients, and systematically analyze the Nash bargaining solution (NBS, game equilibrium) to design the incentive mechanism. It should be noted that the existingsequential bargainingis not suitable for incentivizing FL due to high (exponential) time complexity, which deteriorates the straggler problem in FL. Our formulated bargaining game is challenging due to the NP-hardness. We propose a probabilistic greedy-based client selection algorithm and derive an analytical payment solution as an approximate NBS. We prove the convergence guarantee of our incentive mechanism for communication-efficient FL. Finally, we conduct experiments over real-world datasets to evaluate the performance of our incentive mechanism.

Smart Parking Services (SPSs) enable cruising drivers to find the nearest parking lot with available spots, reducing the traveling time, gas, and traffic congestion. However, drivers risk the exposure of sensitive location data during parking query to an untrusted Smart Parking Service Provider (SPSP). Our motivation arises from a repetitive query to an updated database, i.e., how a driver can be repetitively paired with a previously-matched-but-forgotten lot. Meanwhile, we aim to achieve repetitive query in an oblivious and unlinkable manner. In this work, we present Mnemosyne2 : decentralized and privacy-preserving smart parking with secure repetition and full verifiability. Specifically, we design repetitive, oblivious, and unlinkable Secure k Nearest Neighbor (SkNN) with basic verifiability (correctness and completeness) for encrypted-andupdated databases. We build a local Ethereum blockchain to perform driver-lot matching via smart contracts. To adapt to the lot count update, we resort to the immutable blockchain for advanced verifiability (truthfulness). Last, we utilize decentralized blacklistable anonymous credentials to guarantee identity privacy. Finally, we formally define and prove privacy and security. We conduct extensive experiments over a real-world dataset and compare Mnemosyne2 with existing work. The results show that a query only needs 8 seconds (175 ms) on average for service waiting (verification) among 500 drivers.

Blockchain technology has become a research hotspot in distributed systems, aiming to sustain a decentralized ledger via consensus. Traditional consensus solutions exhibit slow processing speed and response time, resulting in poor performance. To address this issue, several consensus protocols have been proposed. One such popular protocol is HotStuff, a Byzantine fault-tolerant consensus (BFT) that achieves high throughput at the cost of latency. However, its throughput suffers from a proportional decrease with the increase in latency, posing a significant challenge. In this paper, we propose a new protocol called Dolphin that builds upon HotStuff. It operates in a partially synchronous network with$n$replicas, up to$f$byzantine faults, where$n \ge 3f+1$, and achieves higher throughput in high-latency environments by leveraging non-blocking concurrent block generation. Specifically, we formalize our strategy as a generic Asynchronization Procedure Patch and prove that it does not affect the execution process of the original protocol. Theoretical analysis validates that Dolphin preserves the safety, liveness, and responsiveness properties while enhancing the throughput. The evaluation demonstrates that Dolphin typically achieves more than 10x higher throughput in Wide Area Network (WAN) environments with lower latency compared to HotStuff and its variants, and exhibits similar bandwidth utilization to DAG-based protocols such as Narwhal.

As graph data becomes increasingly prevalent in mobile computing scenarios, deploying Graph Convolutional Network-based self-supervised learning (GCN-SSL) models on mobile devices provides a powerful solution for analyzing graph data and enhancing the intelligence of various mobile services. However, ensuring the legitimacy and security of these models is crucial to protect against compromised or unauthorized versions that could lead to security vulnerabilities or intellectual property issues. In this work, we propose PoGSSL, a verifiable proof of GCN-SSL model training that authenticates model integrity and provenance by checking the reproducibility of the specific model training process. We then introduce SecVerGSSL from PoGSSL to provide privacy-preserving verified computation services. SecVerGSSL offloads the entire computation to the cloud and equips servers with customized secure components, enabling effective verified computation over secret-sharing encrypted training data and PoGSSL. Extensive experiments demonstrate that SecVerGSSL offers verification accuracy indistinguishable from plaintext results, with overhead on the verifier-side requiring at most 10.35 milliseconds and 65.98 KB per epoch.

Federated learning (FL) is a distributed machine learning framework where multiple clients collaboratively train a model without sharing their data. Despite advancements, traditional FL methods encounter challenges including communication overhead, extended latency, and slow convergence. To address these issues, this paper introduces Anchor-HHFL, a novel approach that combines the strengths of synchronous and asynchronous FL. Anchor-HHFL employs multi-tier edge servers which conduct partial model aggregation and reduce the frequency of communication with the central server. Anchor-HHFL implements a novel divergence control method through hierarchical pullback. It orchestrates the sequence of each client's stochastic gradient descent (SGD) updates to pull the locally trained models towards an anchor model, ensuring alignment and minimizing divergence. Simultaneously, a secondary process collects client models without disrupting their ongoing local computations and transmits them to edge servers, thereby overlapping computation with communication, substantially enhancing the training speed. Additionally, to effectively handle asynchronous updates across clusters, Anchor-HHFL uses a heuristic weight assignment for global aggregation, weighting clients’ updates based on the degree of their divergence from the global model. Extensive experiments on MNIST and CIFAR-10 datasets demonstrate Anchor-HHFL's superiority, achieving up to$3 \times$faster convergence and higher test accuracy compared to the baselines.

Federated Learning is particularly challenging in IoT environments, where edge and cloud nodes have imbalanced computation capacity and networking bandwidth. The main scalability barrier in distributed stochastic gradient descent-based machine learning frameworks is the communication overhead from frequent model parameter exchanges between workers and the central server. One way to reduce this overhead is by employing constant and periodic averaging, which sends model parameters to the server after a few iterations of local updates from workers. However, investigations have shown that the optimal communication period for balancing communication and convergence is not constant. Although some studies have explored the effectiveness of federated learning with a constant period, dynamically adjusting the period for optimal convergence remains under-explored. To address this, we investigate the impact of the period on global model convergence and propose an adaptive period control mechanism (AdaPC). This mechanism adaptively adjusts the aggregation period of the federated learning framework to achieve fast convergence with minimal communication. Our theoretical and empirical findings demonstrate that our proposed solution achieves faster convergence, lower final training loss, and minimized communication overhead compared to the constant period averaging strategy and other existing solutions.

Applying the serverless paradigm to edge computing improves edge resource utilization while bringing the benefits of flexible scaling and pay-as-you-go to latency-sensitive applications. This extends the boundaries of serverless computing and improves the quality of service for Function-as-a-Service users. However, as an emerging cloud computing paradigm, serverless edge computing faces pressing challenges, with one of the biggest obstacles being delay caused by excessively long container cold starts. Cold start delay is defined as the time between when a serverless function is triggered and when it begins to execute, and its existence seriously impacts resource utilization and Quality of Service (QoS). In this paper, we study how to minimize the total system cost by caching function containers and selecting routes for neighboring functions via edge or public clouds. We prove that the proposed problem is NP-hard even in the special case where the user request contains only one function, and that the unpredictability of user requests and the impact between adjacent time decisions require that the problem to be solved in an online fashion. We then design the Online Lazy Caching algorithm, an online algorithm with a worst-case competitive ratio using a randomized dependent rounding algorithm to solve the problem. Extensive simulation results show that the proposed online algorithm can achieve close-to-optimal performance in terms of both total cost and cold start cost compared to other existing algorithms, with average improvements of 31.6% and 51.7%.

Privacy-preserving online multi-task assignment is a crucial aspect of spatial crowdsensing on untrusted platforms, where multiple real-time tasks are allocated to appropriate workers in a privacy-preserving manner. While existing schemes ensure the privacy of tasks and users, they seldom focus on minimizing the total moving distances for crowdsensing workers when assigning multiple tasks in real time, which adversely impacts the efficiency of online multi-task assignments. To address this issue, we propose POTA, the first privacy-preserving online multi-task assignment scheme with path planning that minimizes the total moving distances for crowdsensing workers without additional noise. POTA cryptographically implements the extended minimum-cost flow model, which models the encrypted data of workers and tasks in a graph and later produces optimized routing. With such a secure path-planning component, POTA reduces the total moving distances by$25.19\%-52.78\%$in the tested dataset compared with the state-of-the-art schemes with obfuscated path planning. Security analysis proves that POTA guarantees the confidentiality of sensitive data, a stronger security property than introducing obfuscation to sensitive data. Experimental evaluations on real-world datasets demonstrate the feasibility of POTA in terms of running time and its ability to achieve minimized total moving distances.

Fuzzy min-max neural network (FMNN) is one kind of three-layer models based on hyperboxes that are constructed in a sequential way. Such a sequential mechanism inevitably leads to the input order and overlap region problem. In this study, we propose a deep FMNN (DFMNN) based on initialization and optimization operation to overcome these limitations. Initialization operation that can solve the input order problem is to design hyperboxes in a simultaneous way, and side parameters have been proposed to control the size of hyperboxes. Optimization operation that can eliminate overlap region problem is realized by means of deep layers, where the number of layers is immediately determined when the overlap among hyperboxes is eliminated. In the optimization process, each layer consists of three sections, namely, the partition section, combination section, and union section. The partition section aims to divide the hyperboxes into a nonoverlapping hyperbox set and an overlapping hyperbox set. The combination section eliminates the overlap problem of overlapping hyperbox set. The union section obtains the optimized hyperbox set in the current layer. DFMNN is evaluated based on a series of benchmark datasets. A comparative analysis illustrates that the proposed DFMNN model outperforms several models previously reported in the literature.

In this article, we propose the concept of random polynomial neural networks (RPNNs) realized based on the architecture of polynomial neural networks (PNNs) with random polynomial neurons (RPNs). RPNs exhibit generalized polynomial neurons (PNs) based on random forest (RF) architecture. In the design of RPNs, the target variables are no longer directly used in conventional decision trees, and the polynomial of these target variables is exploited here to determine the average prediction. Unlike the conventional performance index used in the selection of PNs, the correlation coefficient is adopted here to select the RPNs of each layer. When compared with the conventional PNs used in PNNs, the proposed RPNs exhibit the following advantages: first, RPNs are insensitive to outliers; second, RPNs can obtain the importance of each input variable after training; third, RPNs can alleviate the overfitting problem with the use of an RF structure. The overall nonlinearity of a complex system is captured by means of PNNs. Moreover, particle swarm optimization (PSO) is exploited to optimize the parameters when constructing RPNNs. The RPNNs take advantage of both RF and PNNs: it exhibits high accuracy based on ensemble learning used in the RF and is beneficial to describe high-order nonlinear relations between input and output variables stemming from PNNs. Experimental results based on a series of well-known modeling benchmarks illustrate that the proposed RPNNs outperform other state-of-the-art models reported in the literature.

The metaverse, as an emerging technical term, conceptually aims to construct a virtual digital space that runs parallel to the physical world. Due to human behaviors and interactions being represented in the virtual world, security in the metaverse is a challenging issue in which the traditional centralized service model is one of the threat sources. To conquer the obstacle caused by centralized computing, blockchain-based solutions are potential problem-solving methods. However, it is difficult for a single blockchain to support large-scale data and business services in the metaverse, due to the scalability restrictions. Moreover, multi-chain settings also encounter the interoperability issues. In this work, we propose a Relay chain and Asynchronous consensus-based Consortium blockchain cross-Chain model, which realizes message transmission and cross-chain transactions in multiple chains by adopting the relay chain and cross-chain gateways. All nodes of the application chains and the relay chain execute cross-chain transactions in sequence and reach a consensus on transactions at any transmission delay. Our experiment evaluations demonstrate that our approach performs well in atomicity, security, and functionality (cross-chain transactions), such that the performance of blockchain scalability in the metaverse can be improved, compared with the traditional relay chain schemes.

Nowadays, the emerging short video streaming applications have gained substantial attention. With the rapidly burgeoning demand for short video streaming services, maximizing their Quality of Experience (QoE) is an onerous challenge. Current video preloading algorithms cannot determine video preloading sequence decisions appropriately due to the impact of users’ swipes and bandwidth fluctuations. As a result, it is still ambiguous how to improve the overall QoE while mitigating bandwidth wastage to optimize short video streaming services. In this article, we devise Gamora, a buffer-aware short video streaming system to provide a high QoE of users. In Gamora, we first propose an unordered preloading algorithm that utilizes a Deep Reinforcement Learning (DRL) algorithm to make video preloading decisions. Then, we further devise an Asymmetric Imitation Learning (AIL) algorithm to guide the DRL-based preloading algorithm, which enables the agent to learn from expert demonstrations for fast convergence. Finally, we implement our proposed short video streaming system prototype and evaluate the performance of Gamora on various real-world network datasets. Our results demonstrate that Gamora significantly achieves QoE improvement by 28.7%–51.4% compared to state-of-the-art algorithms, while mitigating bandwidth wastage by 40.7%–83.2% without sacrificing video quality.

The advent of 6G networks promises revolutionary advances in dynamism, intelligence, and decentralization. Realizing the full potential of 6G requires adaptable service level agreements (SLAs) that can optimize performance based on dynamic network conditions. In this paper, we suggested a method based on the Hyperledger Sawtooth blockchain’s smart contract with the Reptile meta-learning algorithm to solve the rigidity of static SLA and centralization problems. In order to sustain the quality of service in the radio access network and core network domain of 6G networks, this work focuses on SLA management for efficient resource allocation for the eMBB-plus slice. Our approach entails breaking down static SLAs into finer-grained components, transferring those components onto Hyperledger Sawtooth smart contracts, and using the Reptile meta-learning algorithm to forecast SLA metrics and resource requirements. A dynamic tariff model, also proposed within the smart contract, handles increased user demands. We evaluate the solution by analyzing Reptile performance, resource allocation, and SLA violations under dynamic demands. Results demonstrate the efficiency of this AI-driven, blockchain-based approach for automated, optimized 6G eMBB-plus resource management adhering to dynamic fine-grained SLAs. This work highlights the synergistic potential of AI and blockchain for trusted and intelligent 6G service delivery.

The e-health system enables online healthcare by supporting health data transmission services on medical platforms. Considering the frequent privacy breaches in e-health systems and the issuance of relevant regulations, it is important to ensure the authenticity and privacy of health data. Existing e-health systems either fail to provide data authenticity or neglect privacy protection after patients leave the system. In this article, we put forward a secure and efficient e-health system for data transmission, named PPED, to solve this dilemma. In PPED, we explore a regular signature and a forward-secure signature, which guarantee data authenticity and give the signature a valid period. Then, a specific epochal signature scheme is designed by combining two signature schemes with the time-lock puzzle. Since expired epochal signatures are forgeable, patients after leaving the e-health system can forge expired signatures to deny their relationship with the signed data, thus achieving privacy protection. Detailed security analysis demonstrates the PPED realizes data authenticity and user privacy. Extensive experiments evaluate our system and the results show it is practical in terms of running time.

While smart grid significantly facilitates energy efficiency by using users’ power consumption data, it poses privacy leakage risk for user personal behaviors. Differential privacy (DP) has emerged as a promising solution to address this issue. However, existing approaches suffer from severe data utility degradation due to the intensive noise introduced by DP. Additionally, some of these methods are vulnerable to security attacks. To bridge this gap, in this paper, we propose ABDP (accuratebilling-enableddifferentiallyprivate), a mechanism that achieves high-strength DP while ensuring accurate aggregation and billing operations without compromising security. In particular, we propose aggregated and individual noise cancellation algorithms to counteract the negative effects of noise on data utility. Specifically, our ABDP ensures precise aggregation and accurate billing calculations for the power grid and individual users, respectively Furthermore, we present a Blockchain smart contract exploiting the pseudo random function to enforce a fair and secure data reporting process. Theoretical analysis is provided to evaluate the privacy and security guarantees of ABDP. Experimental results on real-world datasets, namely NERL-DATA and REDD, demonstrate that ABDP achieves error-free aggregation and billing calculation, offers arbitrary intensity privacy protection against non-intrusive load monitoring and filtering attacks, and outperforms existing state-of-the-art approaches.

Video analytics play a pivotal role in enhancing the safety of intelligent surveillance and autonomous driving. However, the transmission of vast video data and the computational demands of video analytics present challenges within traditional cloud computing paradigms. To address latency concerns, dynamic video analytics often leverage edge deployments. Nevertheless, the efficient allocation of resources at the edge, balancing cost-effectiveness and accuracy, becomes crucial, especially when multiple video analytics services concurrently operate within the system. This paper introduces an edge-centric incentive mechanism designed to encourage greater participation from edge nodes in offloading tasks. The key focus is on addressing the dynamic nature of edge resources and optimizing system returns through a rational pricing mechanism. We propose a decentralized Soft Actor-Critic algorithm grounded in game theory (DSACG) to autonomously learn the optimal pricing strategy. A comprehensive theoretical analysis, supported by extensive simulations, substantiates the effectiveness of our proposed solution.

The 360-degree video streaming service provides a unique immersive viewing experience for users, who can freely change their Field-of-View (FoV) to view different portions of the videos. However, the demands for high throughput and low latency for 360-degree video pose substantial challenges to the current network infrastructure. Super Resolution (SR) is the procedure for reconstructing high-resolution images from low-resolution ones. Hence, caching video content on the network edge in advance, which is near end users, and applying the SR technique can significantly alleviate the transmission latency. In this article, we describeNOVA, an efficientNeural-OptimizedViewportAdaptive 360-degree video streaming system to improve the Quality of Experience (QoE) of users. In NOVA, we first design a foveated rendering SR approach to super-resolve video tiles utilizing computational resources at the edge. Subsequently, we present a meta-learning-based Multi-Agent Reinforcement Learning (MARL) algorithm to select SR depths and video tiles inside users’ viewports for agile video tile adaptation to optimize overall QoE under frequent network fluctuations. Finally, we implement the holistic prototype of NOVA and evaluate its performance on various real-world network datasets. Extensive experiments illustrate that compared to the state-of-the-art algorithms, NOVA improves average user-perceived QoE by up to 27%.

Outsourcing data users’ location data to a cloud server (CS) enables them to obtain$k$nearest points of interest. However, data users’ privacy concerns hinder the wide-scale use. Several studies have achieved Secure k Nearest Neighbor (SkNN) query, but do not addresstime-restricted accessorresult privacy, and randomly partition data items which degrades efficiency. In this article, we proposeTime-restricted,verifiable, andefficientQueryProcessing (TiveQP). TiveQP has three distinguishing features. 1) Expand SkNN: data users can query$k$nearest locations open at a specific time. 2) Adopt a stronger threat model: we assume the CS is malicious and proposecomplementary set(i.e., transform proving “in” a set to proving “in” its complementary set) to allow data users to verify results without leaking unqueried data items’ information. 3) Improve efficiency: we design a space encoding technique and a pruning strategy to improve efficiency in query processing and result verification. We formally proved the security of TiveQP in the random oracle model. We conducted extensive evaluations over a Yelp dataset to show that TiveQP significantly improves over existing work, e.g., top-10NN query over 100 thousand data items only needs 10 ms to get queried results and 1.4 ms for verification.

The rapid development of blockchain technology has led to a constant increase in its financial and technological value. However, this has also led to malicious attacks. Distributed denial-of-service attacks pose a considerable threat to blockchain technology out of many attacks due to its effectiveness and distributed nature. To protect the blockchain from DDoS attacks, researchers have proposed a large number of defensive schemes. However, these schemes are not well-suited for use in practical situations. In this work, we propose a DDoS attack detection scheme based on centralized federated learning, where multiple participating nodes locally train models and upload them to a central node for aggregation. Additionally, we propose a more suitable method for blockchain scenarios, using decentralized federated learning technology, where multiple nodes exchange models in a peer-to-peer manner to complete model training without a central server. We simulate DDoS attacks in blockchain and generate a large dataset by combining it with traditional network layer DDoS attack data to evaluate the effectiveness of our schemes. The experimental results show that the proposed schemes perform well in classification accuracy, demonstrating that our techniques can detect DDoS attacks effectively.

Blockchain technology builds an immutable and append-only ledger in peer-to-peer networks, which attracts attention from various fields. However, traditional chain-based blockchain systems typically have the problem of low throughput, leading to unsatisfactory performance. Among the proposed solutions, introducing a structure of the Directed Acyclic Graph (DAG) into the blockchain reaches a high transaction throughput. Such an approach enables blocks to refer to more than one previous block, thus processing blocks in parallel with better performance. However, existing DAG-based blockchain schemes do not establish a deterministic rule for block reference priority. Adversaries can initiate a splitting attack to select block references to affect DAG topology, making the consensus unstable. In this paper, we propose a more stable consensus protocol named Phantasm, aiming to stabilize the ordering result in the consensus protocol. The referred blocks can be decided after computing a solution to the block puzzle and the difficulty of this solution affects the number of block references. We design two strategies to guide the honest nodes to select references so that they can resist the splitting attacks to stabilize the ordering. Theoretical analysis and simulation experiments show that Phantasm is more stable than the classic DAG-based blockchain consensus protocol Phantom regarding the ordering results.

Non-intrusive load monitoring (NILM) aims to decompose aggregated electrical usage signal into appliance-specific power consumption and it amounts to a classical example of blind source separation tasks. Leveraging recent progress on deep learning techniques, we design a new neural NILM model {\em Multi-State Dual CNN} (MSDC). Different from previous models, MSDC explicitly extracts information about the appliance's multiple states and state transitions, which in turn regulates the prediction of signals for appliances. More specifically, we employ a dual-CNN architecture: one CNN for outputting state distributions and the other for predicting the power of each state. A new technique is invented that utilizes conditional random fields (CRF) to capture state transitions. Experiments on two real-world datasets REDD and UK-DALE demonstrate that our model significantly outperform state-of-the-art models while having good generalization capacity, achieving 6%-10% MAE gain and 33%-51% SAE gain to unseen appliances.

The deep learning based fault diagnosis methods show excellent performance. However, cost and delay factors make it difficult for their widespread industrial application. Microcontroller units (MCUs) in industrial equipment have the advantages of real-time response and high reliability and usually have some redundant computational resource. However, even lightweight deep learning models cannot be deployed in MCUs due to severely limited computational resources. This paper proposes an end-edge collaborative fault diagnosis framework, by combining real-time decision-making at the end with dynamic adaptive diagnosis at the edge to improve inference performance. The model’s minimum input size is deduced through theoretical analysis of the bearing working mechanism, and to make the model suitable for MCUs, we leverage the differential characteristics of the bearing vibration data and proposed a TinyML model based on stacked autoencoders. The pre-autoencoder extracts differential features, while the post-autoencoder performs fault diagnosis based on pooled differential features. Finally, the stacked-autoencoder model and collaborative framework were evaluated using the CWRU bearing dataset, achieving 384x compression in parameter size and 100% accuracy for binary fault classification, requiring only 6.44kB RAM. With the dynamic adaptive collaboration mechanism, the proposed fault diagnosis framework can reduce the edge load by approximately 94%.

Distributed key generation (DKG) allows bootstrapping threshold cryptosystems without relying on a trusted party, nowadays enabling fully decentralized applications in blockchains and multiparty computation (MPC). While we have recently seen new advancements for asynchronous DKG (ADKG) protocols, their performance remains the bottleneck for many applications, with only one protocol being implemented (DYX+ ADKG, IEEE S&P 2022). DYX+ ADKG relies on the Decisional Composite Residuosity assumption (being expensive to instantiate) and the Decisional Diffie-Hellman assumption, incurring a high latency (more than 100s with a failure threshold of 16). Moreover, the security of DYX+ ADKG is based on the random oracle model (ROM) which takes hash function as an ideal function; assuming the existence of random oracle is a strong assumption, and up to now, we cannot find any theoretically-sound implementation. Furthermore, the ADKG protocol needs public key infrastructure (PKI) to support the trustworthiness of public keys. The strong models (ROM and PKI) further limit the applicability of DYX+ ADKG, as they would add extra and strong assumptions to underlying threshold cryptosystems. For instance, if the original threshold cryptosystem works in the standard model, then the system using DYX+ ADKG would need to use ROM and PKI. In this paper, we design and implement a modular ADKG protocol that offers improved efficiency and stronger security guarantees. We explore a novel and much more direct reduction from ADKG to the underlying blocks, reducing the computational overhead and communication rounds of ADKG in the normal case. Our protocol works for both the low-threshold and high-threshold scenarios, being secure under the standard assumption (the well-established discrete logarithm assumption only) in the standard model (no trusted setup, ROM, or PKI).

Nowadays, cloud-edge communication has emerged as a promising communication paradigm, which leverages edge devices to provide a series of advantages, such as a fast response for end devices. However, considering complicated communication environments, a practical requirement is improving security by constructing decentralized and traceable communications. Currently, blockchains have been widely applied in cloud-edge communications to ensure decentralization and traceability by consensus. Despite these promising benefits, existing transparent and immutable blockchains inevitably introduce two limitations to data rights governance in blockchain-based cloud-edge communications. The first limitation is that transparent blockchains can hardly guarantee data confidentiality since data is accessible to all users, especially unauthorized users. The second limitation is that immutable blockchains can hardly support improper content redaction, which violates the right to be forgotten in GDPR. This paper proposes FDRG, the first fine-grained data rights governance scheme in blockchain-based cloud-edge communications. FDRG cryptographically ensures the right downward compatibility and user collusion resistance. Specifically, based on attributes and policies, FDRG partitions users into three roles (i.e., unauthorized user, readable user, and editable user) and ensures that editable users are compatible with the rights of readable users. The punchline is that FDRG leverages the linear secret sharing matrix-based secret sharing to govern the distribution of data decryption keys and chameleon hashes trapdoors. Formal security analysis proves the security of FDRG under the chosen-plaintext attack in the random oracle model. A full implementation on the FISCO blockchain platform shows that FDRG achieves competitive efficiency compared to state-of-the-art related schemes.

Vertical Federated Learning (VFL) effectively addresses the issue of data isolation, which makes data mining secure. Most VFL implementations rely on a single server or third party for training, which will be terminated if the server or third party fails. In addition, the model accuracy trained by VFL depends on the quality of the client’s local features; nevertheless, the client’s local feature quality is difficult to verify. There exists a chance that the features owned by the client are irrelevant to the model or the intermediate results submitted by the client are inaccurate, such that the model’s accuracy will be seriously affected. In order to solve the single point failure and model accuracy issues in VFL, this paper first proposes a Blockchain – based Decentralized VFL (BDVFL) training model. With the integration of blockchain and the VFL training process, the nodes within the blockchain are categorized into non-training and training nodes. Our method focuses on the scenario in which all training nodes possess labeled data and actively engage in the training procedure of VFL. To be specific, first, each client utilizes local features and initial models to carry out forward activation and generate intermediate results. Second, we randomly choose a training node and combine it with the intermediate results from all clients to formulate the loss function. Finally, each client updates the local model by using the gradient. To protect the raw features, a blinding factor is utilized for safeguarding the intermediate results submitted by the client, such that the training nodes cannot infer the local features from intermediate results. To mitigate the interference of irrelevant training outcomes from clients on the model’s accuracy, we propose a verifiable aggregation method to assess the validity of the intermediate results submitted by the clients. We have conducted both theoretical and experimental analysis, and the results demonstrate the effectiveness of the proposed method.

Ethereum has received increasing attention as the first blockchain platform to support smart contracts. Data mining has become an important tool for analyzing Ethereum transactions. However, existing methods have the disadvantage of covering partial transactions and being vulnerable to privacy-enhancing techniques. In this paper, we propose a scheme for transaction correlation with the node as an entity, which can cover all transactions while being resistant to privacy-enhancing techniques. Utilizing timestamps relayed from N fixed nodes to describe the network properties of transactions, we cluster transactions that enter the network from the same source node. Experimental results show that our method can determine with 97% precision whether two transactions enter the network from the same source node.

In recent years, Internet of Things (IoT) technology has gained a lot of attention. With the development of IoT technology, it comes the need for devices with different trust domains to interact and collaborate. In order to protect the security and reliability of the communication between devices in different trust domains, it raises the concerns about the technology of cross-domain authentication. Traditional cross-domain authentication methods may lead to heavy key management overhead or depend on trusted third parties, while existing blockchain-based cross-domain authentication schemes do not prevent the possibility of mischief by malicious domain managers. In this article, we design an efficient Blockchain and trusted execution environment (TEE)-assisted secure device authentication scheme for cross-domain IoT system, called blockchain and TEE-assisted authentication. Our solution solves the problem that managers are not fully trusted, which in turns protect the security and reliability in the blockchain-based cross-domain communication. Specifically, blockchain is introduced to build trust between different domains, the identity-based signatures are used to verify the identity information of devices and the TEE is introduced to prevent the possibility of mischief by domain managers. Finally, our experiments show that the introduction of TEE has greatly improved system security with a low-efficiency reduction, which proves that our scheme can achieve highly secure distributed IoT authentication.

With the rapid advances in information and communication technologies, the Internet of Things (IoT) has become large and complex, bearing tremendous amounts of data and running devices in various scenarios. Leveraging artificial intelligence (AI) technologies, IoT can achieve superior information extraction, data analytics, and decision making, which has resulted in the revolutionized AI of Things (AIoT). AIoT can alleviate the pressure of storage, computation, and communication. Despite the promising features brought by combining AI technologies into IoT infrastructure, AIoT systems still face some serious challenges including inadequate efficiency, violation of security and privacy, lack of trust, and insufficient incentive. Blockchain featured by its distributed consensus and incentive mechanisms can be a promising technology for addressing the challenges in AIoT. AIoT employing blockchain is evolving with expectations of achieving efficient, secure, and trusted network activities. In this article, we first introduce the background of AIoT and blockchain. Then, we discuss the motivations for employing blockchain with its characteristics in AIoT. Furthermore, we comprehensively review existing solutions on blockchain for AIoT systems from the aspects of efficiency, security, privacy, trust, and incentive. Finally, we discuss the challenges and future research directions on blockchain for AIoT.

Blockchain has been a promising infrastructure for enabling secure data sharing for the Internet of Things (IoT). With the widespread of IoT applications, security issues, such as data privacy, anonymity, and accountability become critical concerns for the users, which are essential principles for secure communication in those applications. However, the existing blockchain-based data-sharing schemes mainly consider data privacy. Only a few works can support anonymity with strong, trusted assumptions. Thus, there is a research gap on the anonymity of blockchain-based data sharing for IoT, which does not rely on any trusted party. In this article, we propose a blockchain-based anonymous data-sharing scheme (BA-DS) by adopting a novel public key encryption derived from a ring signature. In BA-DS, we remove the trusted party and ensure anonymity by using an unconditional linkable ring signature and Signature of Knowledge (SoK). During the revocation, we apply blockchain infrastructure to record the valid revocation list and generate a tag for data stored on the cloud, providing solid accountability. The formal security analysis shows that BA-DS is selective indistinguishable secure in the random oracle model. Additionally, we also prove that BA-DS holds anonymity, data privacy, accountability, and authenticity. The extensive experiments indicate that our proposed BA-DS achieves reasonable efficiency in terms of computational complexity, communication overhead, and consumption on the blockchain.

With the rapid development of the global clean energy industry, the electric vehicle (EV) has gradually replaced the traditional fuel vehicle as a promising modern transportation tool due to its environmental friendliness and competitive prices. Its widespread adoption has led to a substantial increase in demand for subsidiary facilities, such as charging piles and stations. Despite the convenience and accessibility offered by charging services, the privacy of EV users may be compromised in the process, as malicious attackers can infer their true identities and consumption habits from service orders. Existing studies introduce blockchain technology into vehicle charging payment scenarios to protect the privacy of EV users. Unfortunately, it cannot achieve the desired full anonymity and may even hinder electricity regulators’ investigation of suspicious transactions and entities. Therefore, designing a vehicle charging payment scheme that simultaneously supports privacy protection and traceability is a challenge. To address these concerns, this article proposes a privacy-preserving and traceable blockchain-based charging payment (PTB-CP) scheme for EVs. It can protect users’ identity privacy and transaction unlinkability and track abnormal transactions or entities in exceptional circumstances. We conduct a comprehensive analysis of PTB-CP from both theoretical and experimental aspects. The analysis results demonstrate that our scheme can realize privacy protection, reliability and authentication, traceability, scalability, and high efficiency.

As a flourishing technical adoption boosted by 5G technology in recent years, Internet of Things (IoT) has become a common implementation in contemporary network-based solutions, such that tons of IoT devices, seen as nodes in the network, are employed. In order to meet the demands of the network edge, IoT devices mostly have limited computation and storage capabilities; however, this setting also introduces trust and security concerns. One of the noticeable threats is that malicious nodes forge or impersonate other legal nodes’ identities, which results in trustworthiness issues. In this article, we focus on the trust issue of IoT device identities and propose a cross-chain-based solution that applies a reply chain for identifying the legality of device nodes. Our proposed relay chain-based IoT model supports secure and reliable data transmission through the relay chain with the authorization and trust of all IoT blockchains. The relay chain realizes the multiparty verification of IoT devices; thus, addressing the trust problem of device identities. The consensus of the relay chain is executed by the arbitration committee nodes rather than all nodes. Considering the efficiency and adaptability, we also have proposed a novel optimal cross-chain decision-making algorithm to optimize the consensus for the identity-oriented relay chain. The proposed algorithm can minimize the cross-chain overhead while ensuring the fairness of the consensus. Our experiment evaluations have demonstrated that the proposed approach could increase the cross-chain efficiency under triple constraints.

Bitcoin is the first decentralized peer-to-peer cryptocurrency that has gained popularity by providing users with transaction anonymity. With the development of Bitcoin and the higher privacy requirements of users, mixing services have emerged to enhance Bitcoin anonymity by obfuscating the flow of funds. However, they are also widely used for illegal activities due to its strong anonymity, especially for money laundering. Therefore, detecting mixing services has great significance for Bitcoin anti-money laundering. In this article, we propose a novel detection scheme to identify the addresses belonging to Bitcoin mixing services. Specifically, we first construct the Bitcoin mixing data set, which summarizes a total of 26 features to describe the transaction behavior of addresses. Next, we design a new classification model, called the Dual Ensemble Classification Model. The model combines the advantages of multiple models based on different algorithms and obtains better classification performance. In order to detect more complex mixing patterns, we also extract transaction subgraphs from the established Bitcoin address-transaction network. The subgraphs are then classified using a kernel-based graph classification method, which is embedded in the model. Comprehensive experiments on three data sets demonstrate the effectiveness of our scheme, and the proposed model has a detection accuracy of 99.84% for the Bitcoin mixing service.

Searchable symmetric encryption (SSE) supports keyword search over outsourced symmetrically encrypted data. Dynamic searchable symmetric encryption (DSSE), a variant of SSE, further enables data updating. Most DSSE works with conjunctive keyword search primarily consider forward and backward privacy. Ideally, the server should only learn the result sets involving all keywords in the conjunction. However, existing schemes suffer from keyword pair result pattern (KPRP) leakage, revealing the partial result sets containing two of query keywords. We propose the first DSSE scheme to address aforementioned concerns that achieves strong privacy-preserving conjunctive keyword search. Specifically, our scheme can maintain forward and backward privacy and eliminate KPRP leakage, offering a higher level of security. The search complexity scales with the number of documents stored in the database in several existing schemes. However, the complexity of our scheme scales with the update frequency of the least frequent keyword in the conjunction, which is much smaller than the size of the entire database. Besides, we devise a least frequent keyword acquisition protocol to reduce frequent interactions between clients. Finally, we analyze the security of our scheme and evaluate its performance theoretically and experimentally. The results show that our scheme has strong privacy preservation and efficiency.

Covert channels serve the construction of cyberspace security. By realizing the secure transmission of data, it is widely used in political and financial fields. Blockchain covert channels have higher reliability and concealment compared to traditional network-based covert channels. However, existing blockchain covert storage channels need to create a large number of transactions to transmit covert information. Creating transactions requires a transation fee, which means that the implementation of blockchain covert storage channels requires a high cost. Besides, created transactions remain on-chain permanently, leading to the threat of covert information being detected. To overcome these limitations, we propose a blockchain covert timing channel framework. Specifically, we utilize inv and getdata messages in the Bitcoin transaction broadcast as carriers and propose three modulation modes to achieve covert channels without cost and leaving no trace. We evaluate the concealment of our modes by K-S, KLD tests, and machine learning approaches. Experimental results show the indistinguishability between traffic carrying covert information and normal traffic. Our channels promise a capacity of 2.4 bit/s.

As an emerging digital concept offering interconnections across multiple platforms, the metaverse provides digital transformations for various aspects of the physical world, facilitated by a few novel technologies, for example, cloud computing offers data support for the digital world. Humans immersed in the metaverse are digital entities who communicate with others or objects, such that ubiquitous access controls (UACs) are indispensable sectors for multiple platforms. However, in the metaverse, UACs have opened a wide scope of bridges for individuals to shuttle the virtual world, which implies that numerous threats exist at the access layer due to a great pool of entries. In this paper, to solve security issues in the UAC setting of the metaverse, we propose a novel blockchain-based multisignature lock for UAC (BMSL-UAC) scheme. All data institutions reconstruct a consortium blockchain system. In addition, our proposed scheme ensures that only authorized users can access an institution’s data. Finally, we abstract the user’s data access behaviors into the transaction information of the consortium blockchain system to realize full life-cycle data management and traceability. To verify the performance of our scheme, a series of experiments are carried out on the Hyperledger, and evaluation results have demonstrated that the resource consumption, delay, and throughput of this scheme are all within a reasonable range.

Many regions are in urgent need of facial masks for slowing down the spread of COVID-19. To fight the pandemic, people are contributing masks through donation systems. Most existing systems are built on a centralized architecture which is prone to the single point of failure and lack of transparency. Blockchain-based solutions neglect fundamental privacy concerns (donation privacy) and security attacks (collusion attack, stealing attack). Moreover, current auditing solutions are not designed to achieve donation privacy, thus not appropriate in our context. In this work, we design a decentralized, anonymous, and secure auditing frameworkAstraeabased on private smart contracts for donation systems. Specifically, we integrate a Distribute Smart Contract (DiSC) with an SGX Enclave to distribute donations, prove the integrity of donation number (intention) and donation sum while preserving donation privacy. With DiSC, we design a Donation Smart Contract to refund deposits and defend against the stealing attack the collusion attack from malicious collector and transponder. We formally define and prove the privacy and security of Astraea by using security reduction. We build a prototype of Astraea to conduct extensive performance analysis. Experimental results demonstrate that Astraea is practically efficient in terms of both computation and communication.

Federated learning (FL) protects training data in clients by collaboratively training local machine learning models of clients for a global model, instead of directly feeding the training data to the server. However, existing studies show that FL is vulnerable to various attacks, resulting in training data leakage or interfering with the model training. Specifically, an adversary can analyze local gradients and the global model to infer clients’ data, and poison local gradients to generate an inaccurate global model. It is extremely challenging to guarantee strong privacy protection of training data while ensuring the robustness of model training. None of the existing studies can achieve the goal. In this paper, we propose a robust privacy-preserving federated learning framework (PILE), which protects the privacy of local gradients and global models, while ensuring their correctness by gradient verification where the server verifies the computation process of local gradients. In PILE, we develop a verifiable perturbation scheme that makes confidential local gradients verifiable for gradient verification. In particular, we build two building blocks of zero-knowledge proofs for the gradient verification without revealing both local gradients and global models. We perform rigorous theoretical analysis that proves the security of PILE and evaluate PILE on both passive and active membership inference attacks. The experiment results show that the attack accuracy under PILE is between$[50.3\%,50.9\%]$, which is close to the random guesses. Particularly, compared to prior defenses that incur the accuracy losses ranging from 2% to 13%, the accuracy loss of PILE is negligible, i.e., only$\pm 0.3\%$accuracy loss.

The neural network has been widely used to train predictive models for applications such as image processing, disease prediction, and face recognition. To produce more accurate models, powerful third parties (e.g., clouds) are usually employed to collect data from a large number of users, which however may raise concerns about user privacy. In this paper, we propose an Efficient and Privacy-preserving Neural Network scheme, named EPNN, to deal with the privacy issues in cloud-based neural networks. EPNN is designed based on a two-cloud model and techniques of data perturbation and additively homomorphic cryptosystem. This scheme enables two clouds to cooperatively perform neural network training and prediction in a privacy-preserving manner and significantly reduces the computation and communication overhead among participating entities. Through a detailed analysis, we demonstrate the security of EPNN. Extensive experiments based on real-world datasets show EPNN is more efficient than existing schemes in terms of computational costs and communication overhead.

With the proliferation of machine learning, the cloud server has been employed to collect massive data and train machine learning models. Several privacy-preserving machine learning schemes have been suggested recently to guarantee data and model privacy in the cloud. However, these schemes either mandate the involvement of the data owner in model training or utilize high-cost cryptographic techniques, resulting in excessive computational and communication overheads. Furthermore, none of the existing work considers the malicious behavior of the cloud server during model training. In this paper, we propose the first privacy-preserving and verifiable support vector machine training scheme by employing a two-cloud platform. Specifically, based on the homomorphic verification tag, we design a verification mechanism to enable verifiable machine learning training. Meanwhile, to improve the efficiency of model training, we combine homomorphic encryption and data perturbation to design an efficient multiplication operation for the encryption domain. A rigorous theoretical analysis demonstrates the security and reliability of our scheme. The experimental results indicate that our scheme can reduce computational and communication overheads by at least 43.94% and 99.58%, respectively, compared to state-of-the-art SVM training methods.

Federated learning (FL) has achieved state-of-the-art performance in distributed learning tasks with privacy requirements. However, it has been discovered that FL is vulnerable to adversarial attacks. The typical gradient inversion attacks primarily focus on attempting to obtain the client’s private input in a white-box manner, where the adversary is assumed to be either the client or the server. However, if both the clients and the server are honest and fully trusted, is the FL secure? In this paper, we propose a novel method called External Gradient Inversion Attack (EGIA) in the grey-box settings. Specifically, we concentrate on the point that public-shared gradients in FL are always transmitted through the intermediary nodes, which has been widely ignored. On this basis, we demonstrate that an external adversary can reconstruct the private input using gradients even if both the clients and the server are honest and fully trusted. We also provide a comprehensive theoretical analysis of the black-box attack scenario in which the adversary has only the gradients. We perform extensive experiments on multiple real-world datasets to test the effectiveness of EGIA. The outcomes of our experiments validate that the EGIA method is highly effective.

Federated learning (FL) models are vulnerable to membership inference attacks (MIAs), and the requirement of individual privacy motivates the protection of subjects where the individual data is distributed across multiple users in the cross-silo FL setting. In this paper, we propose a subject-level membership inference attack based on data augmentation and model discrepancy. It can effectively infer whether the data distribution of the target subject has been sampled and used for training by specific federated users, even if other users (also) may sample from the same subject and use it as part of their training set. Specifically, the adversary uses a generative adversarial network (GAN) to perform data augmentation on a small amount of priori federation-associated information known in advance. Subsequently, the adversary aggregates two different outputs from the global and tested user models using an optimal feature construction method. We simulate a controlled federation configuration and conduct extensive experiments on real datasets that include both image and categorical data. Results show that the area under the curve (AUC) is improved by 12.6% to 16.8% compared to the classical membership inference attack. This is at the expense of the test accuracy of the data augmented with GAN, which is at most 3.5% lower than the real test data. We also explore the degree of privacy leakage between overfitted models and well-generalized models in the cross-silo FL setting and conclude experimentally that the former is more likely to leak individual privacy with a subject-level degradation rate of up to 0.43. Finally, we present two possible defense mechanisms to attenuate this newly discovered privacy risk.

Local differential privacy (LDP) is a promising technique to realize privacy-preserving data aggregation without a trusted aggregator. Normally, an LDP protocol requires each user to locally perturb his raw data and submit the perturbed data to the aggregator. Consequently, LDP is vulnerable to output poisoning attacks. Malicious users can skip the perturbation and submit carefully crafted data to the aggregator, altering the data aggregation results. Existing verifiable LDP protocols, which can verify the perturbation process and prevent output poisoning attacks, usually incur significant computation and communication costs, due to the use of zero-knowledge proofs. In this paper, we analyze the attacks on two classic LDP protocols for frequency estimation, namely GRR and OUE, and propose two verifiable LDP protocols. The proposed protocols are based on an interactive framework, where the user and the aggregator complete the perturbation together. By providing some additional information, which reveals nothing about the raw data but helps the verification, the user can convince the aggregator that he is incapable of launching an output poisoning attack. Simulation results demonstrate that the proposed protocols have good defensive performance and outperform existing approaches in terms of efficiency.

The popularity of vehicles brings parking issues, especially in the downtown area. To tackle these issues, the concept of smart parking is presented, which utilizes industrial Internet of Things (IIoT) devices and vehicular sensor networks (VSNs) to monitor the available parking spaces and nearby traffic conditions. Unfortunately, the centralized architecture of existing solutions cannot guarantee data reliability. Besides, some privacy issues still violate the VSN participants' sensitive information. We propose a novelBlockchain-based smart parking scheme in digital-twin empowered VSNs with privacy protection, named BSDP. In BSDP, the digital twin network is introduced to monitor and predict traffic conditions nearby a parking lot. The blockchain and smart contract are utilized to achieve reliable data storage and correct parking response, respectively. Besides, the privacy of both driver and VSN participants can be protected. Experimental result shows that the proposed BSDP scheme achieves acceptable efficiency in resource-constrained vehicular networks.

Data-driven applications play an important role in modern-time maritime transportation systems, for instance in facilitating decision-making relating to communication and safety. One example application is position data sharing between vessels within the maritime Internet of Things (IoT)-enabled context. When designing such applications, we need to also consider how to ensure data accuracy as well as privacy in a large scale deployment. In this paper, we demonstrate the potential of using blockchain to facilitate privacy-preserving data sharing. Specifically, we develop a zero-knowledge proof-based scheme to protect vessel identities while allowing data sharing, and a commitment-based approach to ensure relationship-related privacy in data trading between participants. Our security and performance evaluations demonstrate the utility of the proposed approach.

The minimum path pair (MPP) query problem is to find the optimal meeting point of two minimum paths for two users in a network, where each user's minimum path has its own departure and destination nodes. However, the MPP query problem on a time-varying network that generally exists in the world remains open. In this study, we investigate the time-varying minimum path pair (TMPP) query problem, where the arcs of the network are time dependent. We first model the TMPP and then propose a time impulse neural network (TINN) to solve the TMPP. In the design of the TINN, the entire network topology is considered as the architecture of the neural network, and each node is viewed as a neuron. The core of an impulse-based neuron consists of six parts: input, impulse receiver, time window selector, neuron storage, impulse sender, and output. Unlike the traditional neural network, the whole neural network does not require a training process but is implemented through an impulse mechanism. The TINN consists of two stages; the first stage is to find the two minimum paths of two users, while the second stage is to calculate the distance between these two minimum paths. The underlying idea of the TINN is to find the minimum path using an impulse mechanism. The minimum path relies on the earliest time impulse stemming from the depart node that arrives at the destination node. With this mechanism, both the minimum path of the network and the distance between two paths can be addressed. Furthermore, theoretical analysis demonstrates the correctness and provides the complexity of the TINN. Experiments of the TINN are carried out based on the well-known New York City Map. A comparative study illustrates the effectiveness of the TINN.

Federated learning (FL) has reshaped the learning paradigm by overcoming privacy concerns and siloed data. In FL, an aggregator schedules a set of mobile users (MUs) to collectively train a global model with their local datasets and subsequently aggregates their model updates. However, the users have many uncertainties like unstable network connections and volatile availability, which leads to the straggler problem and deteriorates the efficiency of the FL system. Besides, the issue of non-IID datasets hinders the convergence performance of the global model. To hurdle the user uncertainties, we associate a deadline with the decision in each round and partially collect MUs' updates after the deadline, which can be achieved by considering surplus budget constraints. Moreover, we introduce fairness constraints for the non-IID issue. We propose a deadline-aware task replication for surplus client scheduling policy, called FEDDATE-CS. FEDDATE-CS is developed based on a novel contextual-combinatorial multi-armed bandit (CCMAB) learning framework with fairness guarantee. We extend the hypercube-based CCMAB framework by integrating the Lyapunov queuing technique and rigorously prove that FEDDATE-CS achieves a sublinear regret bound and provides an$[\mathcal{O}(1/V),\mathcal{O}(V)]$regret-fairness tradeoff for any fairness control factor$V>0$. We conduct extensive evaluations to verify the significant superiority of FEDDATE-CS over benchmarks.

We address privacy and latency issues in edge-cloud computing environments where the neural network training is centralized. This paper considers the scenario where the edge devices are the only data sources for the deep learning model to be trained on the central server. Improper access to the massive amounts of data generated by edge devices could lead to privacy concerns. As a result, existing solutions for preserving privacy and reducing network latency in the edge environment rely on auxiliary datasets with no privacy risks or pre-trained models to build the client side feature extractor. However, finding auxiliary datasets or pre-trained models is not always guaranteed and may be challenging. To bridge this gap and eliminate the reliance on auxiliary datasets or pre-trained models of existing solutions, this paper presents DeepGuess, a privacy-preserving and latency-aware deep-learning framework. DeepGuess introduces a new learning mechanism enabled by the AutoEncoder architecture: inductive learning. With inductive learning, sensitive data stays on devices and is not explicitly sent to the central server to engage in back-propagations. To further enhance privacy, we propose a new local differential privacy algorithm that allows edge devices to apply random noise to features extracted from their sensitive data before being transferred to the non-trusted central server. The experimental evaluation of DeepGuess with various datasets and in a real-world scenario shows that our solution achieves comparable or even higher accuracy than existing solutions while reducing data transfer over the network by more than 50%.

Multi-organization data sharing is becoming increasingly prevalent due to the interconnectivity of systems and the need for collaboration across organizations (e.g., exchange of data in a supply chain involving multiple upstream and downstream vendors). There are, however, data security concerns due to lack of trust between organizations that may be located in jurisdictions with varying security and privacy legislation and culture (also referred to as a zero trust environment). Hence, in such a zero trust setting, one should introduce strengthened, yet efficient, access control mechanisms to facilitate cross-organizational data access and exchange requests. Contemporary access control schemes generally focus on protecting a single objective rather than multiple parties, due to higher security costs. In this article, we propose a blockchain-based access control scheme, designed to facilitate lightweight data sharing among different organizations. Specifically, our approach utilizes the consortium blockchain to establish a trustworthy environment, in which a Role-Based Access Control (RBAC) model is then deployed using our proposed multi-signature protocol and smart contract methods. Evaluation of our proposed approach is performed on the HyperLedger Fabric consortium blockchain platform using both Caliper and BFT-SMaRT benchmarks, and the findings demonstrate the utility of our approach.

The efficacy of Network Function Virtualization (NFV) depends critically on (1) where the virtual network functions (VNFs) are placed and (2) how the traffic is routed. Unfortunately, these aspects are not easily optimized, especially under time-varying network states with different QoS requirements. Given the importance of NFV, many approaches have been proposed to solve the VNF placement and Service Function Chaining (SFC) routing problem. However, those prior approaches mainly assume that the network state is static and known, disregarding dynamic network variations. To bridge that gap, we leverage Markov Decision Process (MDP) to model the dynamic network state transitions. To jointly minimize the delay and cost of NFV providers and maximize the revenue, we first devise a customized Deep Reinforcement Learning (DRL) algorithm for the VNF placement problem. The algorithm uses the attention mechanism to ascertain smooth network behavior within the general framework of network utility maximization (NUM). We then propose attention mechanism-based DRL algorithm for the SFC routing problem, which is to find the path to deliver traffic for the VNFs placed on different nodes. The simulation results show that our proposed algorithms outperform the state-of-the-art algorithms in terms of network utility, delay, cost, and acceptance ratio.

Ethereum leverages ECDSA as the digital signature scheme to validate transactions. From the provable security standpoint, ECDSA built on an 80-bit security Elliptic Curve group can achieve at most 50-bit concrete security, rather than 80-bit security, due to its reduction loss for$2^{30}$signature queries in security analysis. The state-of-the-art ECDSA scheme comes with no de facto formal security guarantee. Although there have been many signatures with higher concrete security, their structures are quite different from ECDSA and a total replacement of the signature field in Ethereum will incur high deployment cost. In this work, we present EthereumX without compromising the signature structure in Ethereum while achieves better security. The security gain is built on top of a new technique named randomness preprocessing module (RPM), which can securely pre-generate and verify randomness with the help of Ethereum. Calling RPM allows to pre-select randomness, which will be used for the subsequent signature, and to verify the randomness, assuring that it is previously generated. We give an instantiation with formal security guarantee and prove that it can be improved to 80-bit concrete security under the same discrete logarithm assumption as ECDSA. From this instantiated scheme, we implement EthereumX via a deployment into a locally simulated network. Experiment results show that EthereumX costs 5 seconds for a block generation which is equal to Ethereum, and generates/verifies at least$17017/10623$transactions per second that is practical enough in application, even if they are slightly slower than Ethereum which generates/verifies at least$17908/11257$transactions per second. We also mention that RMP can be applied to other DL-based signatures for the security improvement.

Edge intelligence is an emerging technology that integrates edge computing and deep learning to bring AI to the network’s edge. It has gained wide attention for its lower network latency and better privacy preservation abilities. However, the inference of deep neural networks is computationally demanding and results in poor real-time performance, making it challenging for resource-constrained edge devices. In this paper, we propose a hierarchical deep learning model based on TreeNet to reduce the computational cost for edge devices. Based on the similarity of the classification categories, we decompose a given task into disjoint sub-tasks to reduce the complexity of the required model. Then a lightweight binary classifier is proposed for evaluating the sub-task inference result. If the inference result of a sub-task is unreliable, our system will forward the input samples to the cloud server for further processing. We also proposed a new strategy for finding and sharing common features across sub-tasks to improve training speed and accuracy. The experimental results on several popular datasets demonstrate the effectiveness of our approach in speeding up inferences while processing most of the input data with a low error rate.

Considerable attention has been paid to dynamic searchable symmetric encryption (DSSE) which allows users to search on dynamically updated encrypted databases. To improve the performance of real-world applications, recent non-interactive multi-client DSSE schemes are targeted at avoiding per-query interaction between data owners and data users. However, existing non-interactive multi-client DSSE schemes do not consider forward privacy or backward privacy, making them exposed to leakage abuse attacks. Besides, most existing DSSE schemes with forward and backward privacy rely on keeping a keyword operation counter or an inverted index, resulting in a heavy storage burden on the data owner side. To address these issues, we propose a non-interactive multi-client DSSE scheme with small client storage, and our proposed scheme can provide both forward privacy and backward privacy. Specifically, we first design a lightweight storage chain structure that binds all keywords to a single state to reduce the storage cost. Then, we present a Hidden Key technique, which preserves non-interactive forward privacy through time range queries, ensuring that data with newer timestamps cannot match earlier time ranges. We conduct extensive experiments to validate our methods, which demonstrate computational efficiency. Moreover, security analysis proves the privacy-preserving property of our methods.

With the application of the Internet of Things (IoT) and cloud computing, the eHealthcare industry has developed markedly, attracting many patients to seek medical treatment in an eHealthcare system. However, for patients who first register in the system, due to lack of experience, an important aspect is to choose appropriate medical services. Considering the sensitivity of health care data and the semi-honest nature of the cloud server, it is a good solution to use searchable encryption (SE) to obtain some historical electronic medical records (EMRs) that are consistent with the patient's symptom keyword combination and have high service scores for reference. However, existing SE schemes still have issues meeting the requirements of the eHealthcare system for flexible authorization and revocation, efficiency, and forward privacy. To resolve these issues, we propose two efficient and privacy-preserving electronic medical records query schemes with forward privacy in a multiuser setting (EPPFM). First, we present the basic scheme EPPFM-I to achieve a multiuser multikeyword exact match query under linear search complexity. In EPPFM-I, we also use the pseudorandom function (PRF) to perform the function of forward privacy. Then, we use a bucket structure to construct the improved scheme EPPFM-II, which has a faster-than-linear search complexity. Finally, we use detailed security analysis and extensive simulations to show the security and efficiency of the proposed schemes, respectively.

In medical cloud computing, more medical data owners are preferred to outsource their sensitive data to the cloud after encryption. Meanwhile, dynamic searchable symmetric encryption (DSSE) provides the capability for data users to query over the dynamically-updated encrypted database. To reduce update leakage, a secure DSSE scheme usually requires forward and backward privacy. However, existing multi-client DSSE schemes with forward and backward privacy require the data owner to keep online to respond to per-query interaction from data users. To address this issue, we propose a multi-client non-interactive DSSE scheme with forward and backward privacy, namely MCNI. The core design of MCNI is leveraging time range queries to achieve non-interactive forward privacy since the past queries cannot be used to search the newly-added timestamps. To enable efficient time range queries, we convert the timestamp and time range into the boolean wildcard form and develop Boolean Wildcard Matching (BWM) algorithm that formulates the match as a dot product calculation problem. Finally, we combine the polynomial fitting technique, time range query, and random matrix multiplication technique to achieve efficient keyword searches without revealing sensitive information. Theoretical analysis and extensive experiments demonstrate the security and effectiveness of our proposed scheme, respectively.

It is increasingly popular to utilize the wisdom of the crowd for knowledge discovery and monetization. Most of the existing knowledge marketplaces in crowdsensing are implemented by a third-party platform, which may compromise users' rights and be vulnerable to incurring attacks in practice. To eliminate the untrustworthy behaviors of the third party and improve tolerance for the attacks, some blockchain-based knowledge marketplaces in crowdsensing have been proposed. However, the existing blockchain-based knowledge marketplaces fail to simultaneously guarantee privacy (i.e., data privacy and task privacy) and quality awareness. In this paper, we design a blockchain-based privacy-preserving quality-aware knowledge marketplace (PQKM) based on truth discovery, secure K-nearest neighbor computation, matrix decomposition, and data perturbation. PQKM privately calculates users' data quality and automatically rewards users based on their data quality. Detailed security analysis demonstrates that PQKM can preserve data privacy and task privacy during knowledge discovery and monetization. Extensive experiments are conducted on the open real-world dataset to show that PQKM has acceptable efficiency and affordable performance.

The growing popularity of Machine learning (ML) that appreciates high quality training datasets collected from multiple organizations raises natural questions about the privacy guarantees that can be provided in such settings. Our work tackles this problem in the context of multi-party secure ML wherein multiple organizations provide their sensitive datasets to a data user and train a Naive Bayes (NB) model with the data user. We propose PPNB, a privacy-preserving scheme for training NB models, based on Homomorphic Cryptosystem (HC) and Differential Privacy (DP). PPNB achieves a balance performance between efficiency and accuracy in multi-party secure ML, enabled flexible switch among different tradeoffs by parameter tuning. Extensive experimental results validate the effectiveness of PPNB.

Knowing model parameters has been regarded as a vital factor for recovering sensitive information from the gradients in federated learning. But is it safe to use federated learning when the model parameters are unavailable for adversaries, i.e., external adversaries’ In this paper, we answer this question by proposing a novel gradient inversion attack. Speciffically, we observe a widely ignored fact in federated learning that the participants’ gradient data are usually transmitted via the intermediary node. Based on this fact, we show that an external adversary is able to recover the private input from the gradients, even if it does not have the model parameters. Through extensive experiments based on several real-world datasets, we demonstrate that our proposed new attack can recover the input with pixelwise accuracy and feasible efficiency.

Abstract With the development of 5G, the wireless Internet of Things (IoT) has become possible; how to provide privacy protections for the communication of IoT devices in a more vulnerable wireless transmission environment is a huge challenge. Thus, steganography is introduced as a safe and effective technology. Blockchain systems have been widely used in the area of steganography. Several works attempted to embed covert data into transactions in public blockchain systems such as Bitcoin, Ethereum and Monero. However, most of them merely focus on putting covert data into certain fields in transactions based on cryptographic algorithms. In this paper, a Covert Transaction Recognition (CTR) model is proposed by the Text Convolutional Neural Networks and Back Propagation Neural Networks. When utilizing the covert data-embedded field for recognizing, our CTR model can attain 0.79 precision and 0.83 recall on average for seven covert transaction construction schemes. The precision and recall can increase by at most 43 and 47%, respectively, if other unembedded fields were additionally exploited for recognition. We further propose a Practical Covert Transaction Construction (PCTC) model. This model fixes the contents in the embedded fields of the constructed transactions, and generates the contents in other fields using Generative Adversarial Networks. Experimental results demonstrated that the precision and recall are greatly decreased when identifying the covert transactions generated by our PCTC model. The data underlying this article are available in ‘covert-transaction-model’, at https://github.com/1997mint/covert-transaction-model.

Time-series data aggregation in Internet of Things applications is a useful operation, where the time-series data is sensed by a group of users, and gathered by the aggregator for real-time analysis. However, some security and privacy challenges still affect the collection and aggregation process. Although existing privacy-preserving solutions achieve strong privacy guarantees, they introduce a fully trusted TA that is difficult to realize in the real world. Besides, they cannot be directly applied in time-series data aggregation scenarios due to unacceptable efficiency. In this article, we propose a privacy-preserving time-series data aggregation scheme with a semi-trusted authority. Moreover, our scheme also supports arbitrary aggregate functions and fault tolerance to enhance the reliability and scalability of data aggregation. Security analysis demonstrates that our proposed scheme achieves$(n-k)$-source anonymity even if$k(k\leq (n-2))$data providers collude with the cloud server. We also conduct thorough experiments based on a simulated data aggregation scenario to show the high computation and communication efficiency of our scheme.

The quality of covert communications is determined by the choice of communication channels and the design of data embedding schemes. Recently, the Bitcoin system is prevalent as a covert communication channel. The consensus mechanism requires participants to spread their found valid blocks under an adjustable difficulty, which provides a stable periodic broadcast channel. Moreover, senders and receivers are difficult to be traced, because the Bitcoin system is pseudonymous. However, since the historical data in the ledger cannot be removed from the Bitcoin system, the openness and the persistent storage of the ledger in the Bitcoin system post new challenges when designing data embedding schemes. More concreteness, most traditional data embedding schemes either design by heuristic or empirical algorithms or use a fixed field to embed data in the transactions. Therefore, the covert data can be recognized once the algorithm is leaked or the pattern is explored. In this article, we first propose a hash chain-based covert data embedding (HC-CDE) scheme. The embedded transactions are difficult to be discovered. We further propose an elliptic curve Diffie–Hellman chain-based covert data embedding (ECDHC-CDE) scheme to enhance the security of the HC-CDE scheme. Experimental analysis on the Bitcoin Testnet verifies the security and the efficiency of the proposed schemes.

The concepts between Internet of Things (IoT) and edge computing are increasingly intertwined, as an edge-computing architecture generally comprises a (large) number of diverse IoT devices. This, however, increases the potential attack vectors since any one of these connected IoT devices can be targeted to facilitate other malicious cyber activities. Physical attacks are generally harder to mitigate and less studied, in comparison to their cyber counterparts. Thus, in this article we present an attack framework targeting true random number generators (TRNGs), which are a key component in cryptosystems for edge devices. We then demonstrate how such a framework can guide our investigation of a commercial ASIC chip that runs ring-oscillator-based TRNG. Specifically, we show that our template power attack, low voltage fault attack, and voltage glitch fault attack do not require prior knowledge of the TRNG implementation.

The recent COVID-19 pandemic has highlighted the importance of food safety and supply chain governance. In other words, we need to ensure traceability along the supply chain and support high-frequency transactions, effective data collections, etc. Thus, we posit the potential of using a lightning network, which is a decentralized traceable paradigm for achieving high-frequency transactions in blockchain-based systems. In addition, we also utilize edge computing to help facilitate data collection. However, a key challenge in securing food supplies is determining the optimal global transaction path in the lightning network while achieving efficiency and meeting the dynamic nature of food supply management. Thus, we propose a blockchain-edge scheme that utilizes our proposed dynamic programming to produce optimal solutions for selecting global transaction paths. Specifically, our scheme optimizes routing fees under existing constraints (e.g., transmission cost, computing resource consumption, and lightning network balance). The findings from our evaluations demonstrate the utility of our proposed approach in facilitating food safety management.

Electronic patient record (EPR) gains popularity in the health care system with easy availability and usually employs searchable encryption to guarantee both record confidentiality and record retrieval. However, traditional searchable encryption schemes cost a linear complexity of database and even reveals the query index. Both problems hinder EPR applications thereby balancing privacy and search efficiency becomes challenging. In this article, we design a cryptographically searchable EPR system named FastPRS which supports strong privacy and high performance. FastPRS is built on top of online/offline puncturable search (OOPS), a newly defined primitive which splits the search process into the offline phase and the online phase and embeds an index in puncturable pseudorandom sets. Leveraging a combination of linearly homomorphic encryption and oblivious transfer, the query index is punctured. OOPS, therefore, hides the query index obliviously and reduces the search complexity to a sublinear size. We also implement a FastPRS prototype system that supports more than 60 000 keywords and evaluation results show that FastPRS optimizes the search efficiency to 417 search operations per millisecond.

The concept of time release provides a new mode of sending information to the future, where the message will be available after a certainly specified period. Time-release encryption (TRE), as a promising approach, has a widespread releasing application and ensures data confidentiality. TRE relies on two main frameworks, one based on the time-lock puzzle and the other based on a trusted third party, while this primitive is impeded by frameworks’ unreliability limitations and time disclosure. We present ReleaseSC, a decentralized and privacy-aware system that combines smart contract with TRE. ReleaseSC leverages a novel three-part architecture that harmonizes time release and contracts, enabling efficient time-hidden smart contract. Our prototype is with reasonable performance through EVM evaluations on both private chain and official test network. ReleaseSC is built on the top of a new cryptographic notion named ID-based TRE that supports a flexible time policy and preserves the to-be-released time. We propose an ID-based TRE instantiation and show rigorous security analysis in formal security models. The insight from ReleaseSC will open more possibilities to address security issues in hybridized cryptography-blockchain systems.

Business organization performs its business activities within a headquarter-branch relationship, especially for multinationals, by establishing work places in accordance with business requirements. The data-driven decision making stimulates the importance of data analysis. Machine learning (ML), as a method of data analysis, automates analytical model building based on the idea that systems can train and learn from data to make decisions with minimal human intervention. For high accuracy, traditional ML algorithms make design tradeoffs, conceding privacy and reliability, and are thereby unable to satisfy strong security demands. To resolve design tensions, in this article, we propose RePEL, which harmonizes functional encryption (FE) and blockchain on top of encrypted learning. RePEL allows the headquarter to only share partial information about business data collected from branches while manages data transfer with the consensus mechanism in the blockchain, which works in a coordinated way for preserving conditional privacy and high reliability. We instantiate a RePEL design with the three-layer framework and formally reduce its security to a provably secure FE scheme. We further deploy Feel_BC to implement a RePEL prototype system, so as to realize the performance evaluation. Experimental results show that RePEL, with the basic premise of privacy and reliability, can achieve high accuracy and reasonable throughputs.

Mobile crowdsensing (MCS) enables a platform to recruit users to collectively perform sensing tasks from requesters. In order to maximize the completion qualities of tasks, an incentive mechanism should be well designed for the platform to incentivize high-quality users’ participation. The existing works largely adopt the Stackelberg game to model the strategic interactions in the incentive mechanism. However, there are practical issues that are less investigated in the context of the Stackelberg-based incentive mechanism. First, the platform has no knowledge about users’ sensing qualities beforehand due to their private information. Second, the platform needs users’ continuous participation in the long run, which results in fairness requirements. Third, it is also crucial to protect users’ privacy due to the potential privacy leakage concerns (e.g., sensing qualities) after completing tasks. In this article, we jointly address these issues and propose the three-stage Stackelberg-based incentive mechanism for the platform to recruit participants. In detail, we leverage combinatorial volatile multiarmed bandits (CVMABs) to elicit unknown users’ sensing qualities. We use the drift-plus-penalty (DPP) technique in Lyapunov optimization to handle the fairness requirements. We blur the quality feedback with tunable Laplacian noise such that the incentive mechanism protects locally differential privacy (LDP). Finally, we carry out experiments to evaluate our incentive mechanism. The numerical results show that our incentive mechanism achievessublinearregret performance to learn unknown quality with fairness and privacy guarantee.

Given the limited bandwidth available in distributed camera systems, it is nearly impossible for cameras to transmit their entire feed to the server in real time. Furthermore, as the number of camera units increases, the processing overheads on the server also increase, resulting in excessive latencies. This article introduces SmartFilter, a new Edge-to-Cloud filtering solution for video analytics. SmartFilter exploits the feedbacks from the running server-side application to filter directly on the camera, frames that are likely to produce the same application result as the previously offloaded ones. Because of its unique filtering mechanism, SmartFilter improves the system’s throughput, latency, and network usage and reduces the server’s processing overhead while maintaining the overall accuracy. SmartFilter is typically a fast and lightweight binary classifier that examines changes within frames to decide when these changes are significant enough to alter the application output. Experiments with various video data sets and in a real-world scenario demonstrate that our solution can achieve 40 FPS on a commodity camera while delivering a filtering efficiency of more than 90%.

The integration of body sensors, cloud computing, and mobile communication technologies has significantly improved the development and availability of e-healthcare systems. In an e-healthcare system, health service providers upload real patients’ clinical data and diagnostic treatments to the cloud server. Afterward, the users can submit queries with specific body sensor parameters, to obtaining pertinent${k}$diagnostic files. The results are ranked based on ranking algorithms that match the query parameters to the ones in diagnostic files. However, privacy concerns arise while matching disease, since the clinical data and diagnostic files contain sensitive information. In this work, we propose two reliable and privacy-preserving Top-${k}$disease matching schemes. The first scheme is constructed based on our proposed weighted Euclidean distance comparison algorithm under secure${k}$-nearest neighbor technique to get${k}$diagnostic files. It allows users to set different weights for each body indicator as per their needs. The second scheme is designed by comparing Euclidean distances under the modified Paillier homomorphic encryption algorithm where a superlinear sequence is used to reduce the computational and communication overhead. The user side incurs slightly higher computational costs, but the trusted party does not need to execute encryption operations. Hence, the proposed two schemes can be applied in different application scenarios. Simulations on synthetic and real data prove the efficiency of the schemes, and security analysis establishes the privacy-preservation properties.

Bitcoin first proposed the Nakamoto consensus that applies proof of work into the blockchain structure to build a trustless append-only ledger. The Nakamoto consensus solves the distributed consistency problem in the public network but wastes too much computing power. Instead of consuming computing resources, many improved consensus schemes address this problem by leveraging miners’ storage resources. However, these schemes fail to let miners store data constantly and usually rely on a dealer to assign data, which is hard to build a reliable decentralized storage system. In this article, we first design a variant consensus algorithm named Proof of Continuous Work (PoCW) with a storage-related incentive mechanism. Miners can accumulate mining advantage by continuously submitting proofs of storage. Then, we present a hash ring-based data allocation algorithm using the blockchain’s state. Combined with both of them, we build a reliable blockchain-based storage system without relying on any third parties. The theoretical analysis and simulation results demonstrate that the proposed system has higher reliability than those existing systems, and we also give practical suggestions about system parameters. Finally, we discuss additional benefits that our system brings.

Sharing data across various Internet of Things (IoT) devices has been a common challenge due to efficiency, security, and stability issues. Blockchain, with security features, is considered to be a potential solution for data sharing in IoT settings. However, traditional blockchain-based solutions cannot satisfy the efficiency requirement of high-frequency data sharing among IoT devices. In this paper, we propose an efficient IoT data sharing approach by adopting the Payment Channel Network (PCN)-extended blockchain. Besides, we develop a homomorphic hashing-based transaction segmentation scheme to solve the issue of low transaction success ratio caused by channel deposit restrictions in PCN. In addition, a Multi-point Relay (MPR)-based multi-path routing scheme has been developed to ensure high-frequency transaction forwarding. The communication overhead of maintaining the routing table is reduced by our proposed Multi-point Relay Selection algorithm, and multiple alternate paths generated by Multiple Routing Path algorithm can improve the transaction success rate. Experiment evaluations have demonstrated that that our proposed approach outperforms the baseline approaches in terms of the transaction efficiency and success ratio.

Incentive plays an important role in knowledge discovery, as it impels users to provide high-quality knowledge. To promise incentive schemes with transparency, blockchain technology has been widely used in incentive schemes. Currently, privacy, reliability, streamlined processing, and quality awareness are major challenges in designing blockchain-based incentive schemes. In this paper, we design a blockchain-based eFficient and pRivacy-preserving qUality-aware IncenTive scheme called FRUIT. With well-designed smart contracts, FRUIT achieves privacy, reliability, streamlined processing, and quality awareness during the whole procedure. Specifically, we design a novel lightweight encryption method by combining matrix decomposition with proxy re-encryption and a privacy-preserving task allocation based on the polynomial fitting function and hash function. Then, we leverage our proposed lightweight encryption and task allocation to build an efficient and privacy-preserving knowledge discovery protocol in order to securely calculate the data quality and truthful knowledge. To promise user reliability in the incentive scheme, we utilize the Dirichlet distribution to realize the automatic reputation prediction based on the data quality by deploying the reputation management on the blockchain. Moreover, we also deploy the payment management on the blockchain, endowing the incentive scheme to reward participants based on the data quality automatically. Through a detailed security analysis, we demonstrate that data privacy and task privacy are well preserved during the whole process. Theoretical analysis and extensive experiments on real-world datasets demonstrate that FRUIT has acceptable efficiency and affordable performance in terms of computation cost, communication overhead, and gas consumption.

The interest in fog computing is growing, including in traditionally conservative and sensitive areas such as military and governments. This is partly driven by the interconnectivity of our society, and advances in technologies such as Internet-of-Things (IoT). However, protecting against privacy leakage is one of several key considerations in fog computing deployment. Therefore, in this paper, we present a privacy-preserving multi-layer access filtering model, designed for a fog computing environment; hence, coined fog-based access filter (FAF). FAF comprises three key algorithms, namely: access filter initialization algorithm, optimal privacy-energy-time algorithm, and tuple reduction algorithm. Also, a hierarchical classification is used to distinguish the protection objectives. Findings from our experimental evaluation demonstrate that FAF allows one to achieve an optimal balance between privacy protection and computational costs.

With the fast development of the electric vehicle (EV) technology, EVs are expected to be the mainstream in future. The large number of EVs facilitate development of the emerging vehicle-to-grid (V2G) technology, which realizes two-way electricity flows between EVs and the power grid. How to achieve fairness and privacy for EVs during electricity/service exchanges remains a challenging problem for V2G. In this article, we propose a privacy-preserving fair exchange schemeV2GExfor V2G based on the blockchain. V2GEx is composed of an extended blockchain that supports zero-knowledge funds, a fair exchange smart contract based on the hashchain micropayment mechanism, and a privacy-preserving protocol for V2G. We further propose a simpler and more efficient scheme called Uni-V2GEx, which preserves privacy for only one party. We also provide a rigorous security proof under the universal composability (UC) model to prove V2GEx's security. To evaluate its efficiency, we implement V2GEx and conduct comprehensive experiments to test its performance in terms of computation cost and processing delay. The experiment results show that V2GEx is highly efficient in that verification of V2GEx transactions costs only 20 ms and the average transaction processing latency is around 6 seconds in a 200-node blockchain network.

Encrypted retrieval ensures the secure retrieval over the encrypted data without sacrificing the confidentiality. Its applications in the database systems have brought this primitive under the spotlight. Once the malicious sender sends the wrong message, conventional encrypted retrieval is arduous to provide message-moderation and even abuse reporting arises when any receiver is allowed to fabricate and convince a malicious message. We introduce the idea of searchable message-moderation, a newly exquisite framework named CleanSE that enables the system to simultaneously provide encrypted retrieval and fallacious reporting resistance. In a nutshell, CleanSE is achieved via a securely technical combination of asymmetric message franking and searchable encryption. We design two CleanSE schemes. The first, calledRecon, leverages designated verifier signatures to generate a report proof such as to prevent fallacious report and undeniability, and assists with designated-server searchable encryption to protect confidentiality and privacy. Our improved scheme is calledReclean. Compared withRecon,Recleanadds an additional algorithm,$\mathsf {Clean}$, to filter forged message and employs asymmetric message franking to provide stronger deniability and accountability. We implement and evaluate prototype of our CleanSE system to highlight its feasibility and practicality.

Mobile crowdsensing has emerged as a popular platform to solve many challenging problems by utilizing users’ wisdom and resources. Due to user diversity, the data provided by different individuals may vary significantly, and thus it is important to analyze data quality during data aggregation. Truth discovery is effective in capturing data quality and obtaining accurate mobile crowdsensing results. Existing works on truth discovery either cannot protect both task privacy and data privacy, or introduce tremendous computational costs. In this paper, we propose an efficient and strong privacy-preserving truth discovery scheme, named EPTD, to protect users’ task privacy and data privacy simultaneously in the truth discovery procedure. In EPTD, we first exploit the randomizable matrix to express users’ tasks and sensory data. Then, based on the matrix computation properties, we design key derivation and (re-)encryption mechanisms to enable truth discovery to be performed in an efficient and privacy-preserving manner. Through a detailed security analysis, we demonstrate that data privacy and task privacy are well preserved. Extensive experiments based on real-world and simulated mobile crowdsensing applications show EPTD has practical efficiency in terms of computational cost and communication overhead.

Users enjoy the convenience of watching videos on smart devices. However, video watching records can be exposed without users’ knowledge and be exploited to infer private information. In this paper, we design and implement a new side-channel attack system, namedvideo aficionado, which can identify video watching information without violating any access control policies on Android. Our system only needs to collect power consumption data of a video playing app, which does not require explicit user permission. The collected data is sent to a remote server, where noise is cleaned and identified by a multi-layer perceptron (MLP) trained classifier. We evaluate our proposed system through a set of carefully designed experiments. Experimental results demonstrate that our system can make an identification with 74.5 percent accuracy on average for each 20-second power measurement segment out of 3918 segments collected from 20 videos. To the best of our knowledge, video aficionado is the first real-time power consumption-based video identification system on smart devices.

In mobile crowdsensing, location-based task recommendation requires each data requester to submit a task-related geometric range to crowdsensing service providers such that they can match suitable workers within this range. Generally, a trusted server (i.e., database owner) should be deployed to protect location privacy during the process, which is not desirable in practice. In this paper, we propose the location privacy-preserving task recommendation (PPTR) schemes with geometric range query in mobile crowdsensing without the trusted database owner. Specifically, we first propose a PPTR scheme with linear search complexity, named PPTR-L, based on a two-server model. By leveraging techniques of polynomial fitting and randomizable matrix multiplication, PPTR-L enables the service provider to find the workers located in the data requester’s arbitrary geometric query range without disclosing the sensitive location privacy. To further improve query efficiency, we design a novel data structure for task recommendation and propose PPTR-F to achieve faster-than-linear search complexity. Through security analysis, it is shown that our schemes can protect the confidentiality of workers’ locations and data requesters’ queries. Extensive experiments are performed to demonstrate that our schemes can achieve high computational efficiency in terms of geometric range query.

Traffic monitoring services collect traffic reports and respond to users’ traffic queries. However, the reports and queries may reveal the user’s identity and location. Although different anonymization techniques have been applied to protect user privacy, a new security threat arises, namely, n-by-1 jamming attack, in which an anonymous contributing driver impersonates$n$drivers and uploads$n$normal reports by using$n$reporting devices. Such an attack will mislead the traffic monitoring service provider and further degrade the service quality. Existing traffic monitoring services do not support customized queries, and private information retrieval techniques cannot be applied directly in traffic monitoring. We formally define the new attack and propose a traffic monitoring scheme TraJ to defend the attack and achieve user-defined location privacy. Specifically, we bridge anonymous contributing drivers without disclosing their speed set by using private set intersection. Each RSU collects time traffic reports and structures a weighted proximity graph to filter out malicious colluding drivers. We design a user-defined privacy-preserving query method by encoding complex road network. We leverage the uploading phase from private aggregation to collect traffic conditions and allow requesting drivers to dynamically and privately query traffic conditions. We provide a formal analysis of TraJ to prove its privacy and security properties. We also construct a prototype based on a real-world dataset and Android smartphones to demonstrate its feasibility and efficiency. A formal analysis demonstrates the privacy and security properties. Extensive experiments illustrate the performance and defense efficacy.

Federated learning (FL) enables data owners to train a joint global model without sharing private data. However, it is vulnerable to Byzantine attackers that can launch poisoning attacks to destroy model training. Existing defense strategies rely on the additional datasets to train trustable server models or trusted execution environments to mitigate attacks. Besides, these strategies can only tolerate a small number of malicious users or resist a few types of poisoning attacks. To address these challenges, we design a novel federated learning methodTDFL,TruthDiscovery basedFederatedLearning, which can defend against multiple poisoning attacks without additional datasets even when the Byzantine users are$\geq 50\%$. Specifically, the TDFL considers different scenarios with different malicious proportions. For Honest-majority setting (Byzantine$< 50\%$), we design a special robust truth discovery aggregation scheme to remove malicious model updates, which can assign weights according to users’ contribution; for Byzantine-majority setting (Byzantine$\geq 50\%$), we use maximum clique-based filter to guarantee global model quality. To the best of our knowledge, this is the first study that uses truth discovery to defend against poisoning attacks. It is also the first scheme which can achieve strong robustness under multiple kinds of attacks launched by high proportion attackers without root datasets. Extensive comparative experiments are designed with five state-of-the-art aggregation rules under five types of classical poisoning attacks on different datasets. The experimental results demonstrate that TDFL is practical and achieves reasonable Byzantine-robustness.

Vehicle platoon, a novel vehicle driving paradigm that organizes a group of vehicles in the nose-to-tail structure, has been considered as a potential solution to reduce traffic congestion and increase travel comfort. In such a platoon system, head vehicles’ performances are usually evaluated by user vehicles’ feedbacks. Selection of an appropriate and reliable head vehicle while not disclosing user vehicles’ privacy has become an interesting problem. In this article, we present a trust-based and privacy-preserving platoon recommendation scheme, called TPPR, to enable potential user vehicles to avoid selecting the malicious head vehicles. The basic concept of TPPR is that each user vehicle holds a trust value, and the reputation score of the head vehicle is calculated via a truth discovery process. To preserve vehicles’ privacy, pseudonyms and Paillier cryptosystem are applied. In addition, novel authentication protocols are designed to ensure that only the valid vehicles (i.e., the vehicles holding the truthful trust values and joining the vehicle platoon) can pass the authentication. A comprehensive security analysis is conducted to prove that the proposed TPPR scheme is secure against several sophisticated attacks in vehicular ad hoc networks. Moreover, extensive simulations are conducted to demonstrate the correctness and effectiveness of the proposed scheme.

Crowdsensing gradually forms a big data market where workers are willing to trade reusable data with different data collectors. It is challenging for the data collector to choose the transaction party due to the changeable value of the data, while determining the transaction price is also a tough issue. In this paper, we research the dynamic data transaction in crowdsensing. The contribution of the new data to the collector is modeled as the Shapley value, with each worker as a player in the cooperative game. The data collector then judges the contribution of the worker and determines the transaction object. To maximum the profit in the transaction, the collector will dynamically adjust the offering price to workers. The contextual bandit model is utilized in the price decision, with each candidate price as an arm and the time-variant data value as the context. Based on the classic LinUCB learning policy, we learn the mapping of the observed data value and the reward, and estimate the optimal reward in current transaction. The simulation on the data demonstrates that the actual reward got by the collector is close to the maximum reward he can get, which verifies the effectiveness of our scheme.

Real-time forwarding prediction for predicting online contents' popularity is beneficial to various social applications for enhancing interactive social behaviors. Cascade graphs, formed by online contents' propagation, play a vital role in real-time forwarding prediction. Existing cascade graph modeling methods are inadequate to embed cascade graphs that have hub structures and deep cascade paths, or they fail to handle the short-term outbreak of forwarding amount. To this end, we propose a novel real-time forwarding prediction method that includes an effective approach for cascade graph embedding and a short-term variation sensitive method for time-series modeling, making the best of cascade graph features. Using two real world datasets, we demonstrate the significant superiority of the proposed method compared with the state-of-the-art. Our experiments also reveal interesting implications hidden in the performance differences between cascade graph embedding and time-series modeling.

Norm emergence is a process where agents in a multi-agent system establish self-enforcing conformity through repeated interactions. When such interactions are confined to a social topology, several self-reinforcing substructures (SRS) may emerge within the population. This prevents a formation of a global norm. We propose incremental social instruments (ISI) to dissolve these SRSs by creating ties between agents. Establishing ties requires some effort and cost. Hence, it is worth to design methods that build a small number of ties yet dissolve the SRSs. By using the notion of information entropy, we propose an indicator called the BA-ratio that measures the current SRSs. We find that by building ties with minimal BA-ratio, our ISI is effective in facilitating the global norm emergence. We explain this through our experiments and theoretical results. Furthermore, we propose the small-degree principle in minimising the BA-ratio that helps us to design efficient ISI algorithms for finding the optimal ties. Experiments on both synthetic and real-world network topologies demonstrate that our adaptive ISI is efficient at dissolving SRS.

Fine-grained website fingerprinting (WF) enables potential attackers to infer individual webpages on a monitored website that victims are visiting, by analyzing the resulting traffic protected by security protocols such as TLS. Most existing studies focus on WF at the granularity of website, which takes website homepages as their representatives for fingerprinting. Fine-grained WF can reveal more user privacy, such as online purchasing habits and video-viewing interests, and can also be employed for web censorship. Due to striking similarly of webpages on a same website, it is still an open problem to conduct fine-grained WF in an accurate and time-efficient way.In this paper, we propose BurNet, a fine-grained WF method using Convolutional Neural Networks (CNNs). To extract differences of similar webpages, we propose a new concept named unidirectional burst, which is a sequence of packets corresponding to a piece of HTTP message. BurNet takes as input unidirectional burst sequences, instead of bidirectional packet sequences, which makes it applicable to local and remote attack scenarios. BurNet employs CNNs to build a powerful classifier, where sophisticated architecture is designed to improve classification accuracy while reducing time complexity in training. We collect real-world datasets from two well-known websites and conduct extensive experiments to evaluate the performance of BurNet. The closed-world evaluation results show that BurNet outperforms the state-of-the-art methods in both attack scenarios. In the more realistic open-world setting, BurNet can achieve 0.99 precision and 0.99 recall. BurNet is also superior to its CNN-based counterparts in terms of training efficiency.

With the prosperity of graph-based applications, it is increasingly popular for graph nodes to have labels in terms of a set of keywords. The top-k nearest keyword (k-NK) query can find a set of k nearest nodes containing a designated keyword to a given source node. In cloud computing era, graph owners prefer to outsource their graphs to cloud servers, leading to severe privacy risk for conducting k-NK queries. The current studies fail to support efficient and accurate k-NK query under the premise of privacy protection.In this paper, we propose a new graph encryption scheme Aton, which enables efficient and privacy-preserving k-NK querying. Based on the symmetric-key encryption and particular pseudo-random functions, we construct a secure k-NK query index. Aton is built on a ciphertext sum comparison scheme which can achieve approximate distance comparison with high accuracy. Rigorous security analysis proves that it is CQA-2 secure. Experiments with real-world datasets demonstrate that it can efficiently answer k-NK queries with more accurate results compared with the state-of-the-art.

Biometrics identification has been used in a growing number of fields in recent years, since it is more secure, classified and convenient. With the development of cloud computing, database systems are able to upload large amounts of biometric data to cloud server for storage and identification to save local memory and improve computational efficiency. However, this involves potential privacy concerns because of the introduction of third-party platforms. In this paper, we achieve computational and communication efficiency in biometric identification, while preserving the privacy of data. Specifically, the database system firstly encrypts all biometric data and query data. Then, it sends the ciphertext to a cloud server to carry out matching tasks. Finally, the cloud server returns the index of final matches to the system so that it can check whether the biometric vector is legal or not. Detailed security analysis indicates that the proposed scheme can resist powerful attacks. Beyond that, Experiments show that the scheme is more efficient in computation and communication than stat of art biometric identification schemes.

Internet of Things (IoT) makes great development and gains popularity with a mature combination with cloud computing. Plaintext data can be encrypted when data owners try to secure the confidentiality, while the encrypted data retrieval can be achieved by a cryptographic primitive named searchable encryption. Public-key encryption with keyword search (PEKS) is built on the asymmetric setting, however, the “honest-but-curious” assumption in PEKS creates challenges on the search reliability when malicious behaviors happen. It is nontrivial to enable the reliable search while preserving keyword privacy, as users who have paid need to receive either correct-and-wanted results or compensations. In this work, we apply blockchain to resolve this problem and design SearchBC, a blockchain-based PEKS framework supporting private, reliable, and fair encrypted search over the asymmetric setting. SearchBC is built on top of the blockchain and a keyword server to allow fairness in transactions and keyword preprocessing. We present a SearchBC instantiation and formally prove its security under the newly defined security model. SearchBC guarantees that search operations are fair and reliable and that the used keyword keeps privacy. The implementation results show that SearchBC provides a feasible means with reasonable communication and computation costs.

Federated learning (FL) serves as an enabling technology for intelligent edge computing, where high-quality machine learning (ML) models are collaboratively trained over large amounts of data generated by various Internet of Things devices while preserving data privacy. To further provide data confidentiality, computation auditability, and participant incentives, the blockchain framework has been incorporated into FL. However, it is an open question whether the model updates from participants in blockchain-assisted FL can disclose properties of the private data the participants are unintended to share. In this article, we propose a novel property inference attack that exploits the unintended property leakage in blockchain-assisted FL for intelligent edge computing. More specifically, we present an active attack to learn the property leakage from model updates of participants and to identify a set of participants with a certain property. We also design a dynamic participant selection strategy tailored to the setting of large-scale FL, which accelerates the selection process of target participants and improves attack accuracy. We evaluate the proposed attack through extensive experiments with publicly available data sets. The experimental results demonstrate that the proposed attack is effective and efficient in inferring various properties of training data, while maintaining the high quality of the main tasks in FL.

In developing smart city, the growing popularity of machine learning (ML) that appreciates high-quality training data sets generated from diverse Internet-of-Things (IoT) devices raises natural questions about the privacy guarantees that can be provided in such settings. Privacy-preserving ML training in an aggregation scenario enables a model demander to securely train ML models with the sensitive IoT data gathered from IoT devices. The existing solutions are generally server aided, cannot deal with the collusion threat between the servers or between the servers and data owners, and do not match the delicate environments of IoT. We propose a privacy-preserving ML training framework named Heda that consists of a library of building blocks based on partial homomorphic encryption, which enables constructing multiple privacy-preserving ML training protocols for the aggregation scenario without the assistance of untrusted servers, and defending the security under collusion situations. Rigorous security analysis demonstrates the proposed protocols can protect the privacy of each participant in the honest-but-curious model and guarantee the security under most collusion situations. Extensive experiments validate the efficiency of Heda, which achieves privacy-preserving ML training without losing the model accuracy.

Combining the Internet-of-Things (IoT) technology with cloud computing is a significant alternative for powering the utilization of computing resources in a connected environment. A grand challenge in communications is raised by the emergence of big data, due to the large-sized data transmissions and frequent data exchanges. Applying fog computing is considered an option for resolving the communication challenge. However, a high extent of available heterogeneous computing attached to fog computing servers leads to a restriction of the resource management. This Article addresses the resource management issue by proposing a novel approach - named Energy-aware Fog Resource Optimization (EFRO) model- to optimizing the utilization of connected devices in fog computing. We develop a heuristic algorithm minimizing both energy cost and time consumption in a holistic way. A salient feature of EFRO lies in the integration of the standardization and smart shift operations fueled by a hill-climbing mechanism to produce near-optimal resource allocation solutions. Experimental results demonstrate that our EFRO is adroit at making near-optimal decisions in managing resources in fog computing environments. In particular, EFRO boosts the energy efficiency of the existing MESF and RR schemes by 54.83 and 71.28 percent, respectively. EFRO shortens DECM's allocation-generation time by up to a factor of 507.

When coming to perform shortest distance queries on encrypted graph data outsourced in external storage infrastructure such as cloud, a significant challenge is how to compute the shortest distance in an accurate, efficient and secure way. This issue is addressed by a recent work, which makes use of somewhat homomorphic encryption (SWHE) to encrypt distance values output by a 2-hop cover labeling (2HCL) scheme. However, it may import large errors and even yield negative results. Besides, SWHE would be too inefficient for normal clients. In this paper, we propose GENOA, a novel Graph ENcryption scheme for shOrtest distAnce queries. GENOA employs only efficient symmetric-key primitives while significantly enhances the accuracy compared to the prior work. As a reasonable trade-off, it additionally reveals the order information among queried distance values in the 2HCL index. We theoretically prove the accuracy and security of GENOA under rigorous cryptographic model. Detailed experiments on eight real-world graphs demonstrate that GENOA is efficient and can produce almost exact results.

Truth discovery has received considerable attention in mobile crowdsensing systems. In real practice, it is vital to resolve conflicts among a large amount of sensory data and estimate the truthful information. Although truth discovery has been widely explored to improve aggregation accuracy, numerous security and privacy issues still need to be addressed. Existing schemes either do not guarantee the privacy of each participating user, or fail to consider practical needs in crowdsensing systems. In this paper, we present two reliable and privacy-preserving truth discovery schemes for different scenarios. Our first design is fit for applications where users are relatively stable. By employing the homomorphic Paillier encryption, one-way hash chain, and super-increasing sequence techniques, this approach not only guarantees strong privacy, but also is highly efficient and practical. Our second design suits applications where users are frequently moving. In such an application, we explore data perturbation and homomorphic Paillier encryption to shift all user workloads to the server side, without compromising users' privacy. Through detailed security analysis, we demonstrate that both schemes are secure, practical, and privacy-preserving. Moreover, extensive experiments based on real world and simulated mobile crowdsensing systems, we demonstrate the efficiency of our proposed schemes.

Encrypted web traffic can reveal sensitive information of users, such as their browsing behaviors. Existing studies on encrypted traffic analysis focus on website fingerprinting. We claim that fine-grained webpage fingerprinting, which speculates specific webpages on a same website visited by a victim, allows exploiting more user private information, e.g., shopping interests in an online shopping mall. Since webpages from the same website usually have very similar traffic traces that make them indistinguishable, existing solutions may end up with low accuracy. In this paper, we propose FineWP, a novel fine-grained webpage fingerprinting method. We make an observation that the length information of packets in bidirectional client-server interactions can be distinctive features for webpage fingerprinting. The extracted features are then fed into traditional machine learning models to train classifiers, which achieve both high accuracy and low training overhead. We collect two real-world traffic datasets and construct closed- and open-world evaluations to verify the effectiveness of FineWP. The experimental results demonstrate that FineWP is superior to the state-of-the-art methods in terms of accuracy, time complexity and stability.

Deep neural networks (DNNs) have been increasingly used in face recognition (FR) systems. Recent studies, however, show that DNNs are vulnerable to adversarial examples, which potentially mislead DNN-based FR systems in the physical world. Existing attacks either generate perturbations working merely in the digital world, or rely on customized equipment to generate perturbations that are not robust in the ever-changing physical environment. In this paper, we propose FaceAdv, a physical-world attack that crafts adversarial stickers to deceive FR systems. It mainly consists of a sticker generator and a convertor, where the former can craft several stickers with different shapes while the latter aims to digitally attach stickers to human faces and provide feedback to the generator to improve the effectiveness. We conduct extensive experiments to evaluate the effectiveness of FaceAdv on attacking three typical FR systems (i.e., ArcFace, CosFace and FaceNet). The results show that compared with a state-of-the-art attack, FaceAdv can significantly improve the success rates of both dodging and impersonating attacks. We also conduct comprehensive evaluations to demonstrate the robustness of FaceAdv.

Decentralized Applications (DApps) are increasingly developed and deployed on blockchain platforms such as Ethereum. DApp fingerprinting can identify users' visits to specific DApps by analyzing the resulting network traffic, revealing much sensitive information about the users, such as their real identities, financial conditions and religious or political preferences. DApps deployed on the same platform usually adopt the same communication interface and similar traffic encryption settings, making the resulting traffic less discriminative. Existing encrypted traffic classification methods either require hand-crafted and fine-tuning features or suffer from low accuracy. It remains a challenging task to conduct DApp fingerprinting in an accurate and efficient way. In this paper, we present GraphDApp, a novel DApp fingerprinting method using Graph Neural Networks (GNNs). We propose a graph structure named Traffic Interaction Graph (TIG) as an information-rich representation of encrypted DApp flows, which implicitly reserves multiple dimensional features in bidirectional client-server interactions. Using TIG, we turn DApp fingerprinting into a graph classification problem and design a powerful GNN-based classifier. We collect real-world traffic datasets from 1,300 DApps with more than 169,000 flows. The experimental results show that GraphDApp is superior to the other state-of-the-art methods in terms of classification accuracy in both closed- and open-world scenarios. In addition, GraphDApp maintains its high accuracy when being applied to the traditional mobile application classification.

Various Artificial Intelligence (AI) techniques are combined with classic side-channel methods to improve the efficiency of attacks. Among them, Genetic-Algorithms-based Correlation Power Analysis (GA-CPA) is proposed to launch attacks on hardware cryptosystems to extract the secret key efficiently. However, the convergence efficiency of GA-CPA is unsatisfactory due to two problems: the randomly generated initial population generally have low fitness, and the mutation operation in each iteration hardly produces high-quality individuals because of the confusion and diffusion characteristics of S-boxes. In this paper, we propose an analysis framework of GA-CPA which focuses on solving these two problems. First, we explore the list of candidate key bytes which is the result of Correlation Power Analysis (CPA) on a limited number of power traces, so that the population can be initialized with high quality candidates. Second, we improve the mutation operation by guiding the candidate key to mutate in a higher-fitness direction instead of randomly. Third, we make full use of the fitness calculation method and combine it with key enumeration algorithms to further improve the efficiency of key recovery. Simulation experimental results show that our method reduces the number of traces by 33.3% and 43.9% compared to CPA with key enumeration and GA-CPA respectively when the success rate is fixed to 90%. Real experiments performed on SAKURA-G confirm that the number of traces required in our method is much less than the numbers of traces required in CPA and GA-CPA. Besides, we adjust our method to deal with DPA contest v1 dataset, and achieve a better result of 40.76 traces than the winning proposal of 42.42 traces. The computation cost of our proposal is nearly 16.7% of the winner.

As more and more organizations deploy their sensing devices in the industrial Internet of Things network, it becomes increasingly important for the organizations to share data with others, so that the value of the data can be fully explored. However, individuals' privacy may be compromised because of data sharing. In this article, we study the differentially private data publishing problem, which aims at balancing between privacy and data utility. Specifically, two blockchain-based data publishing protocols are proposed. For histogram publishing, we propose a protocol where the Laplace noise added in the query result is verified by the blockchain. For anonymized data publishing, we propose a protocol, which can prevent the publisher and the recipient from lying about the utility of the published data. With the blockchain acting as a reliable intermediary between the publisher and the recipient, the proposed protocols can help to realize fair and auditable data sharing.

Unmanned Aerial Vehicles (UAVs) are increasingly deployed in networked environments, such as places of mass gatherings, smart cities and smart nations. For example, UAVs can be deployed to detect violations of lockdown, stay-at-home or social / physical distancing directives during pandemics (e.g. COVID-19). There are, however, security and privacy considerations in such deployments. To achieve secure and efficient authentication of UAVs, solutions such as those based on Point-to-Point (P2P) or a Point- to-Multipoint (P2M) communications have been proposed in the literature. In this article, we present a novel blockchain-based technique to support multi-party authentication to facilitate trustworthy group communications. Specifically, this allows us to provide secure P2P wireless communications and trusted group communication management for UAV networks, while ensuring service efficiency. Evaluation findings from both real-world implementation and simulations demonstrate the utility of the proposed approach.

The Internet of Vehicles (IoV) is one important application scenarios for the development of the Internet of things. The software-defined network (SDN) and fog computing could effectively improve the IoV network dynamics, which enables the application to achieve better performance by offloading some tasks to fog node or cloud center. Current computation offloading approaches for IoV and fog computing mostly focus on resource utilization. However, the energy-aware offloading has not been adequately addressed, especially for IoV systems with many battery-powered roadside units (RSU) and electric vehicles (EV). In this paper, we study the offloading problem in SDN and fog computing-based IoV systems. An energy-aware dynamic offloading scheme is proposed to prolong the running time of the IoV system by leveraging available battery power to execute more applications. The remaining battery power is defined as a dynamic weight factor in the execution cost model to adjust the optimization objective. Meanwhile, the dependence between applications is also taken into consideration in the cost model. A heuristic optimization algorithm is designed to solve the optimization problem. We conducted comprehensive experiments and results have shown that the offloading scheme could execute more applications with the available battery power under the constraints of application dependence.

E-commerce platforms incorporate reputation systems that allow customers to rate suppliers following financial transactions. Existing reputation systems cannot defend the centralized server against arbitrarily tampering with the supplier’s reputation. Furthermore, they do not offer reputation access across platforms. Rates are faced with privacy leakages because rating activities are correlated with privacy (e.g., identity and rating). Meanwhile, raters could be malicious and initiate multiple rating attacks and abnormal rating attacks. Determining how to address these issues have both research and practical value. In this paper, we propose a blockchain-based privacy-preserving reputation system for e-commerce platforms named RepChain; our system allows cross-platform reputation access and anonymous and private ratings. Using RepChain, all e-commerce platforms collaborate and share users’ reputations by co-constructing a consortium blockchain and modeling the rating process as a finite state machine. In particular, we facilitate one-show anonymous credentials constructed from two-move blind signatures to protect customers’ identities and resist multiple rating attacks, leverage zero-knowledge range proof to verify the correctness of ratings and defend against abnormal rating attacks, design a secure sum computation protocol among nodes to update reputations, and verify ratings via batch processing and consensus hashes. Finally, we demonstrate the security and privacy of RepChain via a formal analysis and evaluate its performance based on Ethereum test network.

Side-channel analysis achieves key recovery by analyzing physical signals generated during the operation of cryptographic devices. Power consumption is one kind of these signals and can be regarded as a multimedia form. In recent years, many artificial intelligence technologies have been combined with classical side-channel analysis methods to improve the efficiency and accuracy. A simple genetic algorithm was employed in Correlation Power Analysis (CPA) when apply to cryptographic algorithms implemented in parallel. However, premature convergence caused failure in recovering the whole key, especially when plenty of large S-boxes were employed in the target primitive, such as in the case of AES. In this article, we investigate the reason of premature convergence and propose a Multiple Sieve Method (MS-CPA), which overcomes this problem and reduces the number of traces required in correlation power analysis. Our method can be adjusted to combine with key enumeration algorithms and further improves the efficiency. Simulation experimental results depict that our method reduces the required number of traces by and , compared to classic CPA and the Simple-Genetic-Algorithm-based CPA (SGA-CPA), respectively, when the success rate is fixed to . Real experiments performed on SAKURA-G confirm that the number of traces required for recovering the correct key in our method is almost equal to the minimum number that makes the correlation coefficients of correct keys stand out from the wrong ones and is much less than the numbers of traces required in CPA and SGA-CPA. When combining with key enumeration algorithms, our method has better performance. For the traces number being 200 (noise standard deviation ), the attacks success rate of our method is , which is much higher than the classic CPA with key enumeration ( success rate). Moreover, we adjust our method to work on that DPA contest v1 dataset and achieve a better result (40.04 traces) than the winning proposal (42.42 traces).

Traffic monitoring system empowers cloud server and drivers to collect real-time driving information and acquire traffic conditions. However, drivers are more interested in local traffic, and sending driving reports to a faraway cloud server wastes a lot of bandwidth and incurs a long response delay. Recently, fog computing is introduced to provide location-sensitive and latency-aware local data management in vehicular crowdsensing, but it incurs new privacy concerns since drivers’ information could be disclosed. Although these messages are encrypted before transmission, malicious drivers can upload false reports to sabotage the systems, and filtering out false encrypted reports remains a challenging issue. To address the problems, we define a new security model and propose a privacy preserving traffic monitoring scheme. Specifically, we utilize short group signature to authenticate drivers in a conditionally anonymous way, adopt a range query technique to acquire driving information in a privacy-preserving way, and integrate it to the construction of a weighted proximity graph at each fog node through a WiFi challenge handshake to filter out false reports. Moreover, we use variant Bloom filters to achieve fast traffic conditions storage and retrieval. Finally, we prove security and privacy, evaluate performance with real-world cloud servers.

Collecting driving routes is effective in predicting traffic patterns and alleviating traffic jams. However, due to the sensitivity of the location information, drivers are usually reluctant to share their route information. Although some efforts have been made to address this challenge, most of them either do not consider traffic order issues or fall short of achieving practical efficiency. In this paper, we propose an efficient and privacy-preserving route collection scheme, named EPRC, to solve the above-mentioned problems. The main idea of EPRC is to perform location-aware and traffic order-based route aggregation on drivers' encrypted data using super-increasing sequences and a homomorphic encryption cryptosystem. The proposed scheme achieves better computation and communication efficiency by reducing computational complexity and communication overhead from O(M) to O(1), where M denotes the number of road segments. Security analysis demonstrates the privacy of an individual driver's route is preserved under standard cryptographic assumptions. Performance evaluations via implementing EPRC on mobile devices and systems show EPRC's efficiency in terms of computation and communication costs.

Truth discovery is one of the key technologies to extract truthful information from unreliable sensory data collected by different mobile devices in mobile crowdsensing, but the sensory data and the outputs of truth discovery (i.e., truths and mobile devices' weights) may contain sensitive information and cause serious privacy concerns. In this paper, we propose an efficient and privacy-preServing non-interActive Truth discovEry scheme (SATE) in mobile crowdsensing. Specifically, SATE is designed based on a two-cloud model. First, the sensory data is encoded into two parts (i.e., perturbed data and noises) at the mobile device, which are maintained by two clouds separately. Second, by utilizing an adapted distributed public key homomorphic cryptosystem, two clouds can co-operatively exchange the intermediate weights and truths in a privacy preserving manner and thus achieve privacy-preserving truth discovery without the participation of the mobile devices. Security analysis demonstrates that SATE can provide full privacy protection for sensory data, weights, and truths. Performance evaluation also shows that SATE can achieve high computational efficiency and low communication overhead on the mobile devices, since there is no time-consuming cryptographic operation involved.

With the dramatic increase of video traffic on the Internet, video quality of experience (QoE) measurement becomes even more important, which provides network operators with an insight into the quality of their video delivery services. The widespread adoption of end-to-end encryption protocols such as SSL/TLS, however, sets a barrier to QoE monitoring as the most valuable indicators in cleartext traffic are no longer available after encryption. Existing studies on video QoE measurement in encrypted traffic support only coarse-grained QoE metrics or suffer from low accuracy. In this paper, we propose DeepQoE, a new approach that enables real-time video QoE measurement from encrypted traffic. We summarize critical fine-grained QoE metrics, including startup delay, rebuffering, and video resolutions. In order to achieve accurate and real-time inference of these metrics, we build DeepQoE by employing Convolutional Neural Networks (CNNs) with a sophisticated input and architecture design. More specifically, DeepQoE only leverages packet Round-Trip Time (RTT) in upstream traffic as its input. Evaluation results with real-world datasets collected from two popular content providers (i.e., YouTube and Bilibili) show that DeepQoE can improve QoE measurement accuracy by up to 22% over the state-of-the-art methods.

WiFi access points are sources of considerable security risks as the wireless signals have the potential to leak important private information such as passwords. This article examines the security issues posed by point-of-sale (POS) terminals which are widely used in WiFi-covered environments, such as restaurants, banks, and libraries. In particular, we envisage an attack model on passwords entered on POS terminals. We put forward the WiPOS, a password inference system based on wireless signals. Specifically, the WiPOS is a device-free system that uses two commercial off-the-shelf (COTS) devices to collect WiFi signals. Implementing a new keystroke segmentation algorithm and adopting support vector machine (SVM) classifiers with global alignment kernel (GAK), the WiPOS achieves improvement on both keystroke recognition and password prediction. The experimental results show that the WiPOS can achieve more than 73% accuracy for 6-digit password with the top 100 candidates. This article calls the community to take a closer look at the risks posed by the current ubiquitous WiFi devices.

The prosperity of cloud computing has driven an increasing number of enterprises and organizations to store their data on private or public cloud platforms. Due to the limitation of individual data owners in terms of data volume and diversity, data sharing over different cloud platforms would enable third parties to take advantage of big data analysis techniques to provide value-added services, such as providing healthcare services for customers by gathering medical data from multiple hospitals. However, it remains a challenging task to design effective incentives that encourage secure and collaborative data sharing in multiple clouds. In this paper, we propose a reliable collaboration model consisting of three types of participants, which include data owners, miners, and third parties, where the data is shared via blockchain and recorded by a smart contract. In general, these participants may acquire and store the sharing of data using their private or public clouds. We analyze the topological relationships between the participants and develop some Shapley value models from simple to complicate in the process of revenue distribution. We also discuss the incentive effect of sharing security data and rationality of the designed solution through analysis towards distribution rules.

Industrial Internet of Things (IIoT) is considered as one of the most promising revolutionary technologies to prompt smart manufacturing and increase productivity. With manufacturing being more complicated and sophisticated, an entire manufacturing process usually involves several different administrative IoT domains (e.g., factories). Devices from different domains collaborate on the same task, which raises great security and privacy concerns about device-to-device communications. Existing authentication approaches may result in heavy key management overhead or rely on a trusted third party. Thus, security and privacy issues during communication remain unsolved but imperative. In this paper, we present an efficient block-chain-assisted secure device authentication mechanism BASA for cross-domain IIoT. Specifically, consortium blockchain is introduced to construct trust among different domains. Identity-based signature (IBS) is exploited during the authentication process. To preserve the privacy of devices, we design an identity management mechanism, which can realize that devices being authenticated remain anonymous. Besides, session keys between two parties are negotiated, which can secure the subsequent communications. Extensive experiments have been conducted to show the effectiveness and efficiency of the proposed mechanism.

Cruising for a vacant and economical parking spot causes not only time-consuming and frustrating driving experiences, but fuel waste and air pollution. Public parking spots in crowded cities are scarce and expensive. On the contrary, private parking spots usually have low utilization rates, and the spot suppliers are willing to provide their extra parking resources due to a maintenance cost by charging parking fees. Given this situation, it is imperative to call for a smart parking system that collects and provides private parking spots (e.g., around home or workplace) to ease public parking concerns. However, when the suppliers (drivers) are providing (querying for) parking spots, their privacy (e.g., location, identity) is inevitable to be disclosed and existing parking schemes cannot achieve anonymous authentication and anonymous payment simultaneously. To tackle these problems, we propose an anonymous smart-parking and payment (ASAP) scheme in vehicular networks. Specifically, we use short randomizable signature to provide anonymity and conditional privacy. We achieve quick result matching with hashmap and anonymous payment with E-cash. Security analysis and experimental results show that ASAP can protect privacy in a conditional way and has low computational costs and communication overhead.

The papers in this special section focuses on security and privacy in industry. Industries, governments, and scientific communities are increasingly drawing special attention to competitive advantages that Industry 4.0 can bring to business sustainability and economy of a country. The tendency to couple information technologies (ITs) with the existing operational technologies (OTs) adds new opportunities to improve and optimize operational processes, products, and services in which multiple stakeholders (e.g., end-users) can interact with the new industrial ecosystems to speed up and customize processes. In this sense, Industry 4.0 constitutes a relevant investment source composed of a complex technological showcase in which multiple connections and accesses can arise, seriously impacting on the good performance of the different production and distribution chains associated with smart factories and manufacturing, smart grid systems, smart transportation, or smart health environments.

Contemporarily, two emerging techniques, blockchain and edge computing, are driving a dramatical rapid growth in the field of Internet-of-Things (IoT). Benefits of applying edge computing is an adoptable complementarity for cloud computing; blockchain is an alternative for constructing transparent secure environment for data storage/governance. Instead of using these two techniques independently, in this article, we propose a novel approach that integrates IoT with edge computing and blockchain, which is called blockchain-based Internet of Edge model. The proposed model, designed for a scalable and controllable IoT system, sufficiently exploits advantages of edge computing and blockchain to establish a privacy-preserving mechanism while considering other constraints, such as energy cost. We implement experiment evaluations running on Ethereum. According to our data collections, the proposed model improves privacy protections without lowering down the performance in an energy-efficient manner.

Constrained shortest distance (CSD) queries are a valuable extension of the traditional pairwise shortest distance computation over graph-structured data, where the answers to the queries should fulfill a cost constraint (e.g., the toll payment in road networks). With the popularity of cloud computing, data owners have a strong desire to migrate their privacy-sensitive graphs to remote servers without losing the ability to query them. Existing graph encryption schemes cannot provide security guarantees for CSD queries. In this paper, we present Acro, a graph encryption scheme, which executes approximate CSD queries securely. The homomorphic encryption and the symmetric-key primitives are applied to our scheme. Through a security analysis, we prove that Acro meets the security definition of CQA2-security. The prototype of Acro is implemented and evaluated using real datasets. The results show that our proposal outperforms a state-of-the-art baseline in terms of query accuracy at the cost of enlarging query completion time.

Encrypted traffic classification plays an important role in network management. In this paper, we take as an example of the web browsing application, and propose a machine learning classification scheme, Bali, that can identify the encrypted traffic from various websites. We employ packet length statistics as discriminative features of encrypted traffic. In order to further investigate the differences among encrypted traffic from various websites, we develop a clustering method based on an observation that the first outgoing and incoming packets with specific flags from the same website have similar features. The above two techniques can be incorporated into typical machine learning models (e.g., random forests, SVM, kNN) for traffic classification. Experiment results using real-world datasets demonstrate that the proposed method outperforms the state-of-the-art methods.

Encrypted web traffic can reveal sensitive information of a user, such as their browsing histories. Existing studies on encrypted traffic analysis attacks usually focus on traffic fingerprinting of different websites rather than that of webpages from a same website. Fine-grained webpage fingerprinting allows exploiting more private information of users, e.g., their interests within a news website or an online shopping website. Since webpages from a same website usually have very similar features (e.g., statistical information) that make them indistinguishable, existing solutions may end up with low accuracy. In this paper, we propose a novel webpage fingerprinting method based on a simple and comprehensible idea. We make an observation that the length information of packets in bidirectional interaction between clients and servers can be a distinctive feature in webpage fingerprinting. Then, we extract the cumulative length of a sequence of packets to represent the fingerprint of a specific webpage. More precisely, only the first 100 packets in the loading process of a webpage is considered, thus enabling early-stage fingerprinting. The experimental results with real-world datasets demonstrate that our method is superior to other state-of-the-art approaches in terms of classification accuracy and time complexity. To the best of our knowledge, this is the first work on fine-grained webpage fingerprinting.

With the prevalence of blockchain, more and more Decentralized Applications (DApps) are deployed on Ethereum to achieve the goal of communicating without supervision. Users habits may be leaked while these applications adopt SSL/TLS to encrypt their transmission data. Encrypted protocol and the same blockchain platform bring challenges to the traffic classification of DApps. Existing encrypted traffic classification methods suffer from low accuracy in the situation of DApps.

This paper focuses on the privacy risks of disclosing the community structure in an online social network. By exploiting the community affiliations of user accounts, an attacker may infer sensitive user attributes. This raises the problem of community structure deception (CSD), which asks for ways to minimally modify the network so that a given community structure maximally hides itself from community detection algorithms. We investigate CSD through an information-theoretic lens. To this end, we propose a community-based structural entropy to express the amount of information revealed by a community structure. This notion allows us to devise residual entropy minimization (REM) as an efficient procedure to solve CSD. Experimental results over 9 real-world networks and 6 community detection algorithms show that REM is very effective in obfuscating the community structure as compared to other benchmark methods.

Summary To handle the difficulty in identifying encrypted network traffic in big data environment, a fast and online identification method for encryption network behaviors was proposed. Twitter audios, messages, videos, images, and other encrypted network behaviors were deeply studied in big data environment, and the features were extracted from a lot of encryption network behaviors, and the model database based on the correlation coefficient was established by these features, and the correlation coefficient between the network interactive data and the model database was calculated by acquiring the network interactive data at real time. The reference distance will be proposed and used to eliminate the noise of similar traffic sets; at last, the automatic and online identification of encryption network behaviors based on correlation coefficient and reference distance in big data environment were implemented by combination with the classification threshold, and the online identification rate was about 93% by this method, and the experiment results show the proposed method is applicable and effective.