Vehicle platoon (VP), as a typical form of traffic cooperation, can significantly enhance traffic efficiency and safety in Vehicular Ad hoc Networks (VANETs). However, malicious vehicles in VP poses a severe threat to the security of entire VP, requiring to be efficiently traced by identity authentication. In this paper, we propose a lattice-based efficient and traceable privacy-preserving batch authentication scheme for vehicle platoon in VANETs, named LETA. First, we design a dynamic VP identity structure VPD-Tree which is constructed based on hash tree and pseudonyms of vehicles to preserve privacy. Then, an aggregate signature is constructed based on VPD-tree and modular lattice for secure and efficient batch authentication of VP. Finally, Zero-Knowledge Proofs (ZKP) is applied on the VPD-Tree structure to anonymously and efficiently trace the malicious vehicles of VP. Security analysis shows that LETA achieves stronger security guarantees, thereby offering a more secure solution than existing approaches. Moreover, performance evaluations show that LETA achieves lower computation and communication overheads through the VPD-tree structure and efficient batch authentication scheme.

Credit card fraud brings serious losses to both cardholders and card issuers. To reduce losses caused by fraudulent behaviors, banking institutions establish credit card fraud detection (CCFD) models to identify potential fraudulent behaviors. To develop more effective fraud detection models, banking institutions need to collaborate on model training. Federated learning (FL) enables collaboration on fraud detection model training without exchanging data between banking institutions. Nevertheless, the distribution of transaction data in the real-world is heterogeneous among banking institutions, which may lead to convergence issues in global fraud detection models. Furthermore, the behavior and weights of the model may implicitly contain the cardholders’ personal information, which makes existing federated models prone to transaction data leakage. In this article, we propose aheterogeneous credit cardfrauddetection model based onfederated learning withmembership privacy, called HFDFM. To protect the sensitive information of cardholders, we design a novel mechanism that ensures training-data confidentiality by minimizing the accuracy of the best black-box membership inference attack (MIA) against the model. Unlike previous FL frameworks that either optimize for client drift or for membership privacy, HFDFM simultaneously mitigates drift and provides certified membership privacy through a single min–max game. Additionally, we use the control variable to rectify the client drift in its local update in the scenario of heterogeneous data. Extensive experimental results on three mainstream real-world transaction datasets demonstrate that the proposed HFDFM has advantages in utility compared to 11 SOTA baselines, and the proposed HFDFM can mitigate the risks of MIAs (near random guess).

Transferable adversarial examples are known to cause threats in practical, black-box attack scenarios. A notable approach to improving transferability is using integrated gradients (IG), originally developed for model interpretability. In this paper, we find that existing IG-based attacks have limited transferability due to their naive adoption of IG in model interpretability. To address this limitation, we focus on the IG integration path and refine it in three aspects: multiplicity, monotonicity, and diversity, supported by theoretical analyses. We propose the Multiple Monotonic Diversified Integrated Gradients (MuMoDIG) attack, which can generate highly transferable adversarial examples on different CNN and ViT models and defenses. Experiments validate that MuMoDIG outperforms the latest IG-based attack by up to 37.3% and other state-of-the-art attacks by 8.4%. In general, our study reveals that migrating established techniques to improve transferability may require non-trivial efforts.

The emergence of the large language model (LLM) has shown its superiority in a wide range of disciplines, including language understanding and translation, relational logic reasoning, and even partial differential equations solving. The transformer is the pervasive backbone architecture for the foundation model construction. It is vital to research how to adjust the Transformer architecture to achieve an end-to-end privacy guarantee in LLM fine-tuning. This paper investigates three potential information leaks during a federated fine-tuning procedure for LLM (FedLLM). Based on the potential information leakage, we insert two-stage randomness into FedLLM to provide an end-to-end privacy guarantee solution. The first stage is to train a gradient auto-encoder with a Gaussian random prior based on the statistical information of the gradients generated by local clients. The second stage is fine-tuning the overall LLM with a differential privacy guarantee by adopting appropriate Gaussian noises. We show our proposed method's efficiency and accuracy gains with several foundation models and two popular evaluation benchmarks. Furthermore, we present a comprehensive privacy analysis with Gaussian Differential Privacy (GDP) and Renyi Differential Privacy (RDP).

We study convex optimization problems under differential privacy (DP). With heavy-tailed gradients, existing works achieve suboptimal rates. The main obstacle is that existing gradient estimators have suboptimal tail property, resulting in a superfluous factor of d in the union bound. In this paper, we explore algorithms achieving optimal rates of DP optimization with heavy-tailed gradients. Our first method is a simple clipping approach. Under bounded p-th order moments of gradients, with n samples, it achieves minimax optimal population risk with epsilon less than 1/d. We then propose an iterative updating method, which is more complex but achieves this rate for all epsilon smaller than 1. The results significantly improve over existing methods. Such improvement relies on a careful treatment of the tail behavior of gradient estimators. Our results match the minimax lower bound, indicating that the theoretical limit of stochastic convex optimization under DP is achievable.

Text-to-image (T2I) models excel at generating high-quality images from text via powerful text encoders, but training these encoders demands substantial computational resources.Consequently, many users seek pre-trained text encoders from model plugin-sharing platforms like Civitai and Hugging Face, which introduces an underexplored threat: the potential for adversaries to embed Trojans within these plugins.Existing Trojan attacks often require extensive training data and suffer from poor generalization across different triggers, limiting their effectiveness and scalability.To the best of our knowledge, this paper introduces the first Text-encoder Weight-editing method for Inserting Secret Trojans (TWIST).By identifying the bottleneck MLP layer-the critical point where minimal edits can dominantly control cross-modal alignment-TWIST achieves training-free and data-free Trojan insertion, which makes it highly efficient and practical.The experimental results across various triggers demonstrate that TWIST attains an average attack success rate of 91%, a 78% improvement over the state-of-the-art (SOTA) method proposed in 2024 and highlights the excellent generalization capability.Moreover, TWIST reduces modified parameters by 8-fold and cuts injection time to 25 seconds.Our findings underscore the security risks associated with text encoders in real-world applications and emphasize the need for more robust defense mechanisms.

Vision Transformers (ViTs) have been widely applied in various computer vision and vision-language tasks. To gain insights into their robustness in practical scenarios, transferable adversarial examples on ViTs have been extensively studied. A typical approach to improving adversarial transferability is by refining the surrogate model. However, existing work on ViTs has restricted their surrogate refinement to backward propagation. In this work, we instead focus on Forward Propagation Refinement (FPR) and specifically refine two key modules of ViTs: attention maps and token embeddings. For attention maps, we propose Attention Map Diversification (AMD), which diversifies certain attention maps and also implicitly imposes beneficial gradient vanishing during backward propagation. For token embeddings, we propose Momentum Token Embedding (MTE), which accumulates historical token embeddings to stabilize the forward updates in both the Attention and MLP blocks. We conduct extensive experiments with adversarial examples transferred from ViTs to various CNNs and ViTs, demonstrating that our FPR outperforms the current best (backward) surrogate refinement by up to 7.0% on average. We also validate its superiority against popular defenses and its compatibility with other transfer methods. Codes and appendix are available at https://github.com/RYC-98/FPR.

The success of current Large-Language Models (LLMs) hinges on extensive training data that are collected and stored centrally, called Centralized Learning (CL). However, such a collection manner poses a privacy threat, and one potential solution is Federated Learning (FL), which transfers gradients, not raw data, among clients. Unlike traditional networks, FL for LLMs incurs significant communication costs due to their tremendous parameters. In this study, we introduce an innovative approach to compress gradients to improve communication efficiency during LLM FL, formulating the new FL pipeline named CG-FedLLM. This approach integrates an encoder on the client side to acquire the compressed gradient features and a decoder on the server side to reconstruct the gradients. We also develop a novel training strategy that comprises Temporal-ensemble Gradient-Aware Pre-training (TGAP) to identify characteristic gradients of the target model and Federated AutoEncoder-Involved Fine-tuning (FAF) to compress gradients adaptively. Extensive experiments confirm that our approach reduces communication costs and improves performance (e.g., average 3 points increment compared with traditional CL- and FL-based fine-tuning with several foundation models on well-recognized benchmarks, MMLU and C-Eval). This is because our encoder-decoder, trained via TGAP and FAF, can filter gradients while selectively preserving critical features. Furthermore, we present a series of experimental analyses that focus on the communication efficiency, accuracy, and generalization ability within this privacy-centric framework, providing insights into the development of more efficient and private LLMs fine-tuning.

CRYSTALS-Dilithium has recently been selected as one of the next generation post-quantum signature algorithm standards. However, due to the extensive volume of data elements and the high complexity of operations, post-quantum cryptographic algorithms commonly face significant performance challenges, for which GPU acceleration has proven to be an effective hardware solution. This paper presents an optimized GPU-based implementation of Dilithium, accelerating the algorithm across three dimensions: inter-thread, intra-thread, and inter-block. Specifically, we propose shared memory and loop unrolling techniques to optimize the most time consuming number theoretic transform operation. Meanwhile, we employ a PTX assembly implementation of Montgomery modular multiplication for frequent dot product computations. Experimental results indicate that, compared to the NIST standard implementation, our implementations of Dilithium across all three parameter sets achieve speedups of up to 143x for Gen, 255x for Sign, and 152x for Verify on the GPU 4090. On the GPU A100, the speedups reach 114x for Gen, 158x for Sign, and 124x for Verify.

Label differential privacy (DP) is a framework that protects the privacy of labels in training datasets, while the feature vectors are public. Existing approaches protect the privacy of labels by flipping them randomly, and then train a model to make the output approximate the privatized label. However, as the number of classes K increases, stronger randomization is needed, thus the performances of these methods become significantly worse. In this paper, we propose a vector approximation approach for learning with label local differential privacy, which is easy to implement and introduces little additional computational overhead. Instead of flipping each label into a single scalar, our method converts each label into a random vector with K components, whose expectations reflect class conditional probabilities. Intuitively, vector approximation retains more information than scalar labels. A brief theoretical analysis shows that the performance of our method only decays slightly with K. Finally, we conduct experiments on both synthesized and real datasets, which validate our theoretical analysis as well as the practical performance of our method.

The quality of method names is crucial for the readability and maintainability of programs. However, constructing high-quality method names often presents a significant challenge. To address this issue, numerous method name recommendation approaches have been proposed in existing research. These approaches typically require large-scale, highquality software projects to build benchmark function libraries to recommend or generate method names for given method bodies. They generally rely on extracted function features (including function parameters, return values, etc.) as feature vectors. However, these approaches have limited success rates and accuracy in practical applications. To overcome these limitations, we propose a method name recommendation approach, called LMMName, based on large-language models. This approach considers not only the method body but also its interacting functions (i.e., code context), including called and calling functions, and uses this as input to the large language model to generate method names. Our versatile approach implements LMMName using the state-of-the-art large-language model ChatGPT (4.0). Experimental validation in two medium-sized open-source Java projects demonstrates that method name recommendations using this approach have a success rate of 100%. This represents an improvement of 9.86% and 12.54% compared to the recommendation of the method name based on the source code repository and feature matching, regardless of whether the code context is considered. Taking into account the code context relationships, this approach recommends method names that are completely identical to the original project method names at a rate of 55.54 % and 53.99%, respectively. This marks an increase of 27.76% and 29.60% compared to when code context information is not considered. Furthermore, after factoring in the code context, the F1 metrics of this approach are 74.90% and 67.69%, respectively. These figures represent improvements of 37.17% and 21.08% compared to the machine learning-based code2vec approach, and 50.61% and 33.26% compared to the HeMa heuristic search-based approach. This demonstrates the effectiveness of our proposed approach.

Protection of local differential privacy (LDP) proto-cols against manipulation attacks is an important and challenging problem. We hope to design an attack-agnostic framework, which does not rely on any knowledge of attackers. An early work [1] restricts the attacker's capability by converting each sample into a binary signal. However, the compression of signal leads to severe loss of information, and thus results in unnecessary sacrifice of utility, especially when$\epsilon > 1$. In this paper, we propose a general estimation framework RobustLDP for robust estimation under LDP. The general idea is to send carefully crafted pre-defined information to all users, and then aggregate the feedback at the server. We strike a better tradeoff between preserving information and restricting the attacker's capability. We instantiate RobustLDP for frequency estimation and mean estimation in$\ell_{1}$and$\ell_{2}$support, which serve as building blocks for more advanced tasks. We also establish theoretical guarantees for all possible attacks. The result shows that our method significantly outperforms the existing one for$\epsilon > 1$. Extensive experiments on multiple real-world datasets validate the effectiveness of our method.

Security and privacy are critical in cloud-based Internet of Things (IoT) and Artificial Intelligence of Things (AIoT) applications. As quantum computing advances, Post-Quantum Cryptography (PQC) has emerged as a key technology for ensuring security in future IoT and AIoT architectures. SPHINCS+, a leading post-quantum signature algorithm, has been selected by the National Institute of Standards and Technology (NIST) as one of the next-generation signature standards. However, due to its complex structure and extensive hash operations, SPHINCS+ suffers from slower signature generation and verification compared to other post-quantum algorithms. Consequently, accelerating SPHINCS+ is essential for adapting it to IoT environments. This paper presents a CUDA-based Batch Parallel optimization of SPHINCS+ (CBPSPX), which fully utilizes the computing resources of NVIDIA Graphics Processing Units (GPUs) to enhance the performance of SPHINCS+. Specifically, we propose the Thread Utilization Efficiency Index (TUEI), which can be used to theoretically evaluate the effectiveness of various parallel methods. Then, we propose an intra-block batch processing model that dynamically adjusts parallel task scales within a block to optimize throughput, making it particularly suitable for IoT scenarios requiring high-throughput large-scale device authentication. Meanwhile, we divide the signature generation process into three sub-processes and adopt different parallel strategies based on the thread requirements of each sub-process to maximize the value of TUEI. For the signature verification process, we propose a columnar storage strategy to replace the traditional row storage structure, which significantly improves the performance of batch signature verification. Experimental results indicate that our SPHINCS+ implementations across all three parameter sets are better than previous optimized GPU-based implementations and achieve speedups of 1.4× to 2.5× for signature generation and 4.6× to 11.3× for signature verification on GPU RTX 3090.

Robustness is one of the critical concerns in federated learning. Existing research focuses primarily on the worst case, typically modeled as the Byzantine attack, which alters the gradients in an optimal way. However, in practice, the corruption usually happens randomly, and is much weaker than the Byzantine attack. Therefore, existing methods overestimate the power of corruption, resulting in unnecessary sacrifice of performance. In this article, we build practical algorithms that can withstand realistic corruption, which is weaker than the Byzantine attack, in a better way. Toward this goal, we propose a new iterative filtering approach. In each iteration, it calculates the geometric median of all gradient vectors uploaded from clients and remove the gradients that are far away from the geometric median. A theoretical analysis is then provided, showing that under suitable parameter regimes, gradient vectors from corrupted clients are filtered if the noise is large, while those from benign clients are never filtered throughout the training process. For realistic gradient noise, our approach significantly outperforms existing methods, while the performance under the worst-case attack (i.e., the Byzantine attack) remains nearly the same. Experiments on both synthesized and real data validate our theoretical results, as well as the practical performance of our approach. In particular, we have achieved 3%–10% increase in MNIST and CIFAR10 datasets.

Blockchain sharding is a promising solution for scalability but struggles to reach the expected performance due to the high ratio of cross-shard transactions. Account migration has emerged as a critical approach to optimizing shard performance. However, existing migration solutions suffer from inefficient handling of queued withdrawal transactions from a migrating account and inadequate priority mechanism for migration transaction, resulting in prolonged transaction makespan and reduced system throughput. This paper proposes Caravan, a novel blockchain sharding system for optimizing account migration. First, Caravan proposes a transaction aggregation-based migration scheme to efficiently handle withdrawal congestion post-migration. It incorporates a multi-level Merkle tree and cross-shard synchronization protocol to ensure cross-shard security. Second, Caravan presents an economic incentive-driven priority mechanism that motivates miners to perform transaction aggregation and prioritize migration transactions by increasing the associated revenue. Furthermore, its gas recycling strategy enables users to finance migration costs without awareness or extra expenses. Finally, we develop the Caravan prototype, deploy it on Alibaba Cloud, and experiment with real Ethereum transactions. The results show that compared to the state-of-the-art account migration schemes, Caravan significantly mitigates the transaction surge caused by migration, achieving up to a 3.2× throughput improvement and a 65% reduction in transaction confirmation latency. And users share considerable migration costs without extra expenses, significantly reduce system costs. The code for Caravan is available on GitHub.11Caravan are available athttps://github.com/Caravan-project/Caravan.

Vehicular edge computing (VEC) helps improve the task computational performance of vehicles on roads but has difficulty in defending against eavesdropping and selfish attacks simultaneously. In this paper, we design a reputation-based smart contract with blockchain and propose a multi-agent reinforcement learning (RL) based secure offloading scheme for VEC against both eavesdropping and selfish attacks. This scheme has a three-level hierarchical structure for each vehicle and uses the reputations obtained from the blockchain as the basis to optimize the edge node selection, offloading ratio, and power allocation, which aims to reduce the task computational latency, the vehicle energy consumption and eavesdropping rate. By using a punishment function based on the constraints, this scheme avoids exploring dangerous policies that can cause task failure or severe data leakage. A multi-agent deep RL-based secure offloading scheme is proposed for vehicles with sufficient resources, which evaluates the long-term risk rather than the punishment function to further improve the secure offloading performance. The regret bound is analyzedand the cumulative reward upper bound is provided. Simulation results verify the effectiveness of our schemes as compared with the benchmark.

With the rapid growth of blockchain-based Non-Fungible Tokens (NFTs), data trading has evolved to incorporate NFTs for ownership verification. However, the NFT ecosystem faces significant challenges in copyright protection, particularly when malicious buyers slightly modify the purchased data and remint it as a new NFT, infringing upon the original owner’s rights. In this paper, we propose a copyright-preserving data trading protocol to address this challenge. First, we introduce the Merkle Feature Tree (MFT), an enhanced version of the traditional Merkle Tree that incorporates an AI-powered feature layer above the data layer. Second, we design a copyright challenge phase during the trading process, which recognizes the data owner with highly similar feature vectors and earlier on-chain timestamp as the legitimate owner. Furthermore, to achieve efficient and low-gas feature vector similarity computation on blockchain, we employ Locality-Sensitive Hashing (LSH) to compress high-dimensional floating-point feature vectors into single uint256 integers. Experiments across multiple image feature extraction models show that LSH maintains a high F1 score after compression, effectively supporting similarity-based copyright challenges. Experimental results on the Ethereum Sepolia testnet demonstrate NMFT’s scalability with sublinear growth in gas consumption while maintaining stable latency.

Low-Light Enhancement (LLE) is aimed at improving the quality of photos/videos captured under low-light conditions. It is worth noting that most existing LLE methods do not take advantage of geometric modeling. We believe that incorporating geometric information can enhance LLE performance, as it provides insights into the physical structure of the scene that influences illumination conditions. To address this, we propose a Geometry-Guided Low-Light Enhancement Refine Framework (GG-LLERF) designed to assist low-light enhancement models in learning improved features by integrating geometric priors into the feature representation space. In this paper, we employ depth priors as the geometric representation. Our approach focuses on the integration of depth priors into various LLE frameworks using a unified methodology. This methodology comprises two key novel modules. First, a depth-aware feature extraction module is designed to inject depth priors into the image representation. Then, the Hierarchical Depth-Guided Feature Fusion Module (HDGFFM) is formulated with a cross-domain attention mechanism, which combines depth-aware features with the original image features within LLE models. We conducted extensive experiments on public low-light image and video enhancement benchmarks. The results illustrate that our framework significantly enhances existing LLE methods. The source code and pre-trained models are available at https://github.com/Estheryingqi/GG-LLERF.

Privacy-preserving online ride-hailing (ORH) services can offer riders and drivers a more enhanced travel experience without disclosing their location privacy. Group ride-sharing is specifically designed for riders undertaking long-distance trips, allowing a group of riders with similar travel plans to share a single taxi. However, the lack of integrated route planning in existing privacy-preserving schemes prevents them from effectively matching riders with the most optimal taxi. In this paper, we propose a privacy-preserving group ride-sharing matching scheme, PGRoute, based on leveled fully homomorphic encryption (LFHE). In PGRoute, we propose a privacy-preserving path planning method and design a fast ciphertext-based distance matrix computation protocol for the key time-consuming modules in it to effectively improve the efficiency. PGRoute can plan routes for groups of riders, determine the optimal boarding order, and match the most suitable taxi while protecting the location privacy of both riders and taxi drivers. Theoretical analysis and experimental results demonstrate that PGRoute is secure and efficient within ORH systems. Compared to previous works, PGRoute reduces the pickup time for a group of riders by a factor of 2.9-$7.5\times $, and achieves 2.7-$6.7\times $higher computational efficiency.

Multiview clustering has become a prominent research topic in data analysis, with wide-ranging applications across various fields. However, the existing late fusion multiview clustering (LFMVC) methods still exhibit some limitations, including variable importance and contributions and a heightened sensitivity to noise and outliers during the alignment process. To tackle these challenges, we propose a novel regularized instance weighting multiview clustering via late fusion alignment (R-IWLF-MVC), which considers the instance importance from various views, enabling information integration to be more effective. Specifically, we assign each sample an importance attribute to enable the learning process to focus more on the key sample nodes and avoid being influenced by noise or outliers, while laying the groundwork for the fusion of different views. In addition, we continue to employ late fusion alignment to integrate base clustering from various views and introduce a new regularization term with prior knowledge to ensure that the learning process does not deviate too much from the expected results. After that, we design a three-step alternating optimization strategy with proven convergence for the resultant problem. Our proposed approach has been extensively evaluated on multiple real-world datasets, demonstrating its superiority to state-of-the-art methods.

The demand for mobile terminals to participate in data services is increasingly vital. The General Data Protection Regulation (GDPR) has established several principled requirements for data services. Existing studies focusing on data service put emphasis on data privacy and accessibility. However, they face challenges in achieving data forgetability and portability on mobile devices under GDPR and lack consideration of usage control. In this article, we propose ADSS, an app-level data service scheme for mobile devices that can beavailable-but-invisibleand guarantee fine-grained usage control. ADSS addresses the challenges by executing the logic of data usage in the Trusted Execution Environment (TEE) and managing the TEE states (i.e., data usage states) in the blockchain smart contracts. It not only satisfies the requirements of GDPR, ensuring strong security and confidentiality guarantees, but also enables the functionality of “pay-per-use”. We implement a prototype of the ADSS framework based on ARM Trustzone and conduct experimental evaluations. The results demonstrate that our scheme brings high efficiency compared with other data service schemes and exhibits feasibility on mobile-grade devices.

Crime prediction is a crucial yet challenging task within urban computing, which benefits public safety and resource optimization. Over the years, various models have been proposed, and spatial-temporal hypergraph learning models have recently shown outstanding performances. However, three correlations underlying crime are ignored, thus hindering the performance of previous models. Specifically, there are two spatial correlations and one temporal correlation, i.e., (1) co-occurrence of different types of crimes (type spatial correlation), (2) the closer to the crime center, the more dangerous it is around the neighborhood area (neighbor spatial correlation), and (3) the closer between two timestamps, the more relevant events are (hawkes temporal correlation). To this end, we propose Hawkes-enhanced Spatial-Temporal Hypergraph Contrastive Learning framework (HCL), which mines the aforementioned correlations via two specific strategies. Concretely, contrastive learning strategies are designed for two spatial correlations, and hawkes process modeling is adopted for temporal correlations. Extensive experiments demonstrate the promising capacities of HCL from four aspects, i.e., superiority, transferability, effectiveness, and sensitivity.

Deep clustering with attribute-missing graphs, where only a subset of nodes possesses complete attributes while those of others are missing, is an important yet challenging topic in various practical applications. It has become a prevalent learning paradigm in existing studies to perform data imputation first and subsequently conduct clustering using the imputed information. However, these ``two-stage" methods disconnect the clustering and imputation processes, preventing the model from effectively learning clustering-friendly graph embedding. Furthermore, they are not tailored for clustering tasks, leading to inferior clustering results. To solve these issues, we propose a novel Attribute-Missing Graph Clustering (AMGC) method to alternately promote clustering and imputation in a unified framework, where we iteratively produce the clustering-enhanced nearest neighbor information to conduct the data imputation process and utilize the imputed information to implicitly refine the clustering distribution through model optimization. Specifically, in the imputation step, we take the learned clustering information as imputation prompts to help each attribute-missing sample gather highly correlated features within its clusters for data completion, such that the intra-class compactness can be improved. Moreover, to support reliable clustering, we maximize inter-class separability by conducting cost-efficient dual non-contrastive learning over the imputed latent features, which in turn promotes greater graph encoding capability for clustering sub-network. Extensive experiments on five datasets have verified the superiority of AMGC against competitors.

In numerous real-world applications, it is quite common that sample information is partially available for some views due to machine breakdown or sensor failure, causing the problem of incomplete multi-view clustering (IMVC). While several IMVC approaches using view-shared anchors have successfully achieved pleasing performance improvement, (1) they generally construct anchors with only one dimension, which could deteriorate the multi-view diversity, bringing about serious information loss; (2) the constructed anchors are typically with a single size, which could not sufficiently characterize the distribution of the whole samples, leading to limited clustering performance. For generating view-shared anchors with multi-dimension and multi-size for IMVC, we design a novel framework called Diverse View-Shared Anchors based Incomplete multi-view clustering (DVSAI). Concretely, we associate each partial view with several potential spaces. In each space, we enable anchors to communicate among views and generate the view-shared anchors with space-specific dimension and size. Consequently, spaces with various scales make the generated view-shared anchors enjoy diverse dimensions and sizes. Subsequently, we devise an integration scheme with linear computational and memory expenditures to integrate the outputted multi-scale unified anchor graphs such that running spectral algorithm generates the spectral embedding. Afterwards, we theoretically demonstrate that DVSAI owns linear time and space costs, thus well-suited for tackling large-size datasets. Finally, comprehensive experiments confirm the effectiveness and advantages of DVSAI.

Pre-trained models with large-scale training data, such as CLIP and Stable Diffusion, have demonstrated remarkable performance in various high-level computer vision tasks such as image understanding and generation from language descriptions. Yet, their potential for low-level tasks such as image restoration remains relatively unexplored. In this paper, we explore such models to enhance image restoration. As off-the-shelf features (OSF) from pre-trained models do not directly serve image restoration, we propose to learn an additional lightweight module called Pre-Train-Guided Refinement Module (PTG-RM) to refine restoration results of a target restoration network with OSF. PTG-RM consists of two components, Pre-Train-Guided Spatial-Varying Enhancement (PTG-SVE), and Pre-Train-Guided Channel-Spatial Attention (PTG-CSA). PTG-SVE enables optimal short- and long-range neural operations, while PTG-CSA enhances spatial-channel attention for restoration-related learning. Extensive experiments demonstrate that PTG-RM, with its compact size (<1M parameters), effectively enhances restoration performance of various models across different tasks, including low-light enhancement, deraining, deblurring, and denoising.

Privacy protection of users' entire contribution of samples is important in distributed systems. The most effective approach is the two-stage scheme, which finds a small interval first and then gets a refined estimate by clipping samples into the interval. However, the clipping operation induces bias, which is serious if the sample distribution is heavy-tailed. Besides, users with large local sample sizes can make the sensitivity much larger, thus the method is not suitable for imbalanced users. Motivated by these challenges, we propose a Huber loss minimization approach to mean estimation under user-level differential privacy. The connecting points of Huber loss can be adaptively adjusted to deal with imbalanced users. Moreover, it avoids the clipping operation, thus significantly reducing the bias compared with the two-stage approach. We provide a theoretical analysis of our approach, which gives the noise strength needed for privacy protection, as well as the bound of mean squared error. The result shows that the new method is much less sensitive to the imbalance of user-wise sample sizes and the tail of sample distributions. Finally, we perform numerical experiments to validate our theoretical analysis.

Federated learning (FL) offers distributed machine learning on edge devices. However, the FL model raises privacy concerns. Various techniques, such as homomorphic encryption (HE), differential privacy, and multiparty cooperation, are used to address the privacy issues of the FL model. Among them, HE ensures greater security and privacy since end-to-end encryption maintains data privacy throughout the computation process. Compared with other privacy-preserving techniques, HE does not require the establishment of a trusted environment or protocol among multiple parties and does not involve any artificial noise that can impair system performance. Unfortunately, it suffers from efficiency overhead when applied to privacy-preserving FL (PPFL). Some existing surveys on PPFL discuss the generic construction and organization of PPFL from the perspective of practical HE deployment in PPFL. However, none of them covers the efficiency optimization of HE when applied to PPFL. This article conducts a comprehensive review of the efficiency optimization of HE when applied to PPFL. First, we review general optimization strategies and discuss their limitations when applied directly to HE-based PPFL. Second, an overview of algorithmic, hardware, and hybrid optimizations is provided, along with a discussion of their adaptation. Additionally, we provide a detailed taxonomy of optimizations. Finally, we suggest future HE-based PPFL research directions.

Homomorphic Encryption (HE) enhances data security by enabling computations on encrypted data, advancing privacy-focused computations. The BFV scheme, a promising HE scheme, raises considerable performance challenges. Graphics Processing Units (GPUs), with considerable parallel processing abilities, offer an effective solution. In this work, we present an in-depth study on accelerating and comparing BFV variants on GPUs, including Bajard-Eynard-Hasan-Zucca (BEHZ), Halevi-Polyakov-Shoup (HPS), and recent variants. We introduce a universal framework for all variants, propose optimized BEHZ implementation, and first support HPS variants with large parameter sets on GPUs. We also optimize low-level arithmetic and high-level operations, minimizing instructions for modular operations, enhancing hardware utilization for base conversion, and implementing efficient reuse strategies and fusion methods to reduce computational and memory consumption. Leveraging our framework, we offer comprehensive comparative analyses. Performance evaluation shows a 31.9$\times$speedup over OpenFHE running on a multi-threaded CPU and 39.7% and 29.9% improvement for tensoring and relinearization over the state-of-the-art GPU BEHZ implementation. The leveled HPS variant records up to 4$\times$speedup over other variants, positioning it as a highly promising alternative for specific applications.

Matrix computation is a crucial mathematical tool in scientific fields such as Artificial Intelligence and Cryptographic computation. However, it is difficult for resource-limited devices to execute large-scale matrix computations independently. Outsourcing matrix computation (OMC) is a promising solution that engages a cloud server to process complicated matrix computations for resource-limited devices. However, existing OMC schemes lack public verifiability, and thus resource-limited devices cannot verdict the correctness of the computing results. In this paper, for the first time, we propose a smart contract-based OMC scheme that publicly verifies the outsourcing matrix computation results. In our scheme, a smart contract running over the blockchain serves as a decentralized trusted third party to ensure the correctness of the matrix computation results. To overcome the Verifier's Dilemma in the blockchain, we present a blockchain-compatible matrix verification method that decreases the time complexity from$O(n^{3})$to$O(n^{2})$by utilizing a blinding method with the check digit and padding matrices. We make the verification become the form of comparing whether two results are identical rather than naive re-computing. Finally, we perform experiments on Ethereum and ARM Cortex-M4 and give in-depth analysis and performance evaluation, demonstrating our scheme's practicability and effectiveness.

The onerous media sharing task prompts resource-constrained media owners to seek help from a cloud platform, i.e., storing media contents in the cloud and letting the cloud do the sharing. There are three key security/privacy problems that need to be solved in the cloud media sharing scenario, including data privacy leakage and access control in the cloud, infringement on the owner’s copyright, and infringement on the user’s rights. In view of the fact that no single technique can solve the above three problems simultaneously, two cloud media sharing schemes are proposed in this article, named FairCMS-I and FairCMS-II. By cleverly utilizing the proxy re-encryption technique and the asymmetric fingerprinting (AFP) technique, FairCMS-I and FairCMS-II solve the above three problems with different privacy/efficiency tradeoffs. Among them, FairCMS-I focuses more on cloud-side efficiency while FairCMS-II focuses more on the security of the media content, which provides owners with flexibility of choice. In addition, FairCMS-I and FairCMS-II also have advantages over existing cloud media sharing efforts in terms of optional indistinguishability under chosen-plaintext attack (IND-CPA) security and high cloud-side efficiency, as well as exemption from needing a trusted third party. Furthermore, FairCMS-I and FairCMS-II allow owners to reap significant local resource savings and thus can be seen as the privacy-preserving outsourcing of AFP. Finally, the feasibility and efficiency of FairCMS-I and FairCMS-II are demonstrated by experiments.

Genomic data is usually stored in a decentralized manner among data providers, who cannot share them publicly due to privacy concerns. A significant technical challenge is to combine machine learning and cryptography techniques to build secure machine learning models over distributed datasets without violating privacy. Therefore, data providers in collaborative machine learning want to maintain the privacy of their genomic data, and the researcher who owns the training model wants to keep the model and training methods confidential. This paper proposes a framework that supports secure collaborative learning tasks without disclosing the participants' genomic data and training model information simultaneously. With the help of a cluster of Intel SGX enclaves, our work performs fast distributed training over these enclaves, and a dedicated enclave is solely used for updating the global model. Also, Secure XGBoost was implemented over these hardware enclaves for fast learning and to enhance the enclaves' security with unique data-oblivious algorithms that eliminate side-channel attacks. From the experimental results, our scheme achieves fast and efficient results in collaborative learning systems without an increase in communication overhead, making it practical for large genomic data.

Outsourcing the heavy decryption computation to a cloud service provider has been a promising solution for a resource-constrained mobile device to deploy an attribute-based encryption scheme. However, the current attribute based encryption with outsourced decryption schemes only enable the mobile device to verify whether the cloud service provider has returned a correct decryption result, they lack a mechanism to enable the cloud service provider to escape from a mobile device's wrong claim if it has returned a correct decryption result. This article, for the first time, proposes an attribute based encryption with reliable outsourced decryption scheme using the blockchain smart contract. In the proposed scheme, not only can the mobile device verify whether the cloud service provider has returned a correct decryption result, but also the cloud service provider can escape from a wrong claim if the returned decryption result is correct. Moreover, our system achieves the fairness property, which means the cloud service provider can get the reward from the mobile device if and only if it has returned a correct decryption result. Finally, we conduct an implementation to demonstrate that the proposed scheme is practical and efficient.

Cloud computing, which provides adequate storage and computation capability, has been a prevalent information infrastructure. Secure data sharing is a basic demand when data was outsourced to a cloud server. Attribute-based proxy re-encryption has been a promising approach that allows secure encrypted data sharing on clouds. With attribute-based proxy re-encryption, a delegator can designate a set of shared users through issuing a re-encryption key which will be used by the cloud server to transform the delegator's encrypted data to the shared users’. However, the existing attribute-based proxy re-encryption schemes lack a mechanism of revoking users from the sharing set which is critical for data sharing systems. Therefore, in this article, we propose a concrete attribute-based proxy re-encryption with direct revocation mechanism (ABPRE-DR) for encrypted data sharing that enables the cloud server to directly revoke users from the original sharing set involved in the re-encryption key. We implemented the new schemes and evaluated its performance. The experimental results show that the proposed ABPRE-DR scheme is efficient and practical.

Homomorphic encryption (HE) is a promising technique for privacy-preserving computations, especially the word-wise HE schemes that allow batching. However, the high computational overhead hinders the deployment of HE in real-word applications. GPUs are often used to accelerate execution, but a comprehensive performance comparison of different schemes on the same platform is still missing. In this work, we fill this gap by implementing three word-wise HE schemes BGV, BFV, and CKKS on GPU, with both theoretical and engineering optimizations. We enhance the hybrid key-switching technique, significantly reducing the computational and memory overhead. We explore several kernel fusing strategies to reuse data, resulting in reduced memory access and IO latency, and enhancing the overall performance. By comparing with the state-of-the-art works, we demonstrate the effectiveness of our implementation. Meanwhile, we introduce a unified framework that finely integrates our implementation of the three schemes, covering almost all scheme functions and homomorphic operations. We optimize the management of pre-computation, RNS bases, and memory in the framework, to provide efficient and low-latency data access and transfer. Based on this framework, we provide a thorough benchmark of the three schemes, which can serve as a reference for scheme selection and implementation in constructing privacy-preserving applications.

While side-channel attacks (SCAs) have become a significant threat to cryptographic algorithms, masking is considered as an effective countermeasure against SCAs. On the one hand, securely implementing the scheme is a challenging and error-prone task. It is essential to detect leakage in a complicated cryptographic circuit. However, the traditional method of leakage detection is always inaccuracy or time consumption. On the other hand, the deep learning-based power attacks have shown their threat to the masking without combining functions. Compared to the leakage detection done under the traditional provable security framework, the security evaluation against deep learning-based attacks at the pre-silicon stage has not been discussed. To this end, this paper investigates the strategies of leveraging the deep learning techniques to achieve an efficient leakage location method. In this paper, we present the first approach utilizing deep learning-based leakage location for both unprotected and protected implementations at the pre-silicon stage. Firstly, we propose the leakage location method named Gradient Visualization-based location (GVL), which provides leakage location at the different levels of design. Gradient visualization is known as a sensitivity analysis method to understand better how a natural network can learn to predict the sensitive label based on the input. We theoretically show how the gradient visualization can be used to locate leakage components in the netlist efficiently. Moreover, we link the result with the metric in deep learning-based leakage assessment, which fills the lack of leakage evaluation at the pre-silicon stage against deep learning-based SCAs. We further confirm the effectiveness of the proposed method on unprotected implementation, low entropy masked implementation, and provable secure masked implementation. The results show that the proposed methodology outperforms the traditional location methods in the masked cases, where the time consumption is reduced by about 2x to 10x with fewer false negatives and no false positives.

Mobile smart devices provide convenience for people’s daily life with the users’ data, but also put consumers’ privacy and security at risk. Privacy-enhancing technologies (PETs), including secure two/multi-party computation, have emerged as solutions to alleviate privacy concerns in mobile cloud computing (MCC). However, cloud servers, although capable of easing the burden of PETs, introduce potential risks by being malicious and colluding with computation parties to access additional private data. In this article, we propose a privacy-preserving cloud-assisted two-party computation scheme and the optimized variant with the half-gate method in MCC with a higher security level. To the best of our knowledge, the work is the first cloud-assisted two-party computation, designed to resist all collusion attacks in the malicious model. This is achieved by distributing circuit generation tasks among the parties and separately processing private inputs based on authenticated garbled circuits. Security analysis demonstrates that our scheme ensures correctness and fairness. Performance comparison results indicate the efficiency of our work, even with stronger security against malicious servers and any collusion attack. It outperforms the state-of-the-art scheme, particularly in terms of the server’s communication cost in the online phase, achieving a remarkable reduction of approximately 96.8%.

Private comparison schemes constructed on homomorphic encryption offer the noninteractive and parallelizable features, and have advantages in communication bandwidth and performance. In this work, we propose cuXCMP, an extension of the privacy comparison scheme XCMP (AsiaCCS 2018). We address the relatively small input domain and the incompletely expressible output of XCMP, by modifying the encoding method and devising a constant term extraction (CTX) approach. Then, we describe a method for constructing privacy-preserving decision tree (PPDT) using this scheme. Considering the high computational overhead of CTX, we exploit the massive parallelism of the GPU to accelerate this function. Based on the results of the kernel profiling, we utilize several optimization techniques to improve the performance, including using multiple CUDA streams, reducing the grid dimension, kernel fusion, etc. By accelerating this function, we boost the execution time of the scheme and demonstrate 130× and 1.9× speedups for CTX and cuXCMP, respectively, as well as a 35% reduction in the evaluation time of PPDT.

Prevailing smart devices collect individual or industrial sensitive data for collaborative computation to provide convenient service in heterogeneous networks. Nowadays, protecting privacy and security is a significant issue and raises increasing concerns in academia and industry. But diverse smart devices are equipped with unequal resources and some devices with limited resources cannot afford expensive privacy-preserving computation. In this article, we propose a generic efficient and privacy-preserving cloud-assisted two-party computation scheme for smart devices in heterogeneous networks. We adopt the cloud server to assist the collaborative computation and reduce the overhead of smart devices. Besides, we apply preprocessing and online phases to guarantee different devices to operate with a lower burden online. What is more, the work is, to our best knowledge, the first to resist the malicious cloud server and computing parties simultaneously by adopting authenticated masked bits to strengthen the garbled circuit scheme. At the same time, our scheme can guarantee correctness and fairness, as shown in security analysis. The performance comparison result shows that this work is efficient and surpasses the previous best counterpart scheme while maintaining nearly identical computation cost. It outperforms in terms of total communication cost by 49% and total execution time by 32%, even though it takes extra and acceptable cost in the online phase for stronger security against the malicious server.

Masked graph autoencoder (MGAE) has emerged as a promising self-supervised graph pre-training (SGP) paradigm due to its simplicity and effectiveness. However, existing efforts perform the mask-then-reconstruct operation in the raw data space as is done in computer vision (CV) and natural language processing (NLP) areas, while neglecting the important non-Euclidean property of graph data. As a result, the highly unstable local structures largely increase the uncertainty in inferring masked data and decrease the reliability of the exploited self-supervision signals, leading to inferior representations for downstream evaluations. To address this issue, we propose a novel SGP method termed Robust mAsked gRaph autoEncoder (RARE) to improve the certainty in inferring masked data and the reliability of the self-supervision mechanism by further masking and reconstructing node samples in the high-order latent feature space. Through both theoretical and empirical analyses, we have discovered that performing a joint mask-then-reconstruct strategy in both latent feature and raw data spaces could yield improved stability and performance. To this end, we elaborately design a masked latent feature completion scheme, which predicts latent features of masked nodes under the guidance of high-order sample correlations that are hard to be observed from the raw data perspective. Specifically, we first adopt a latent feature predictor to predict the masked latent features from the visible ones. Next, we encode the raw data of masked samples with a momentum graph encoder and subsequently employ the resulting representations to improve the predicted results through latent feature matching. Extensive experiments on seventeen datasets have demonstrated the effectiveness and robustness of RARE against state-of-the-art (SOTA) competitors across three downstream tasks. Our source code is available athttps://github.com/WxTu/RARE.

Deep clustering, which can elegantly exploit data representation to seek a partition of the samples, has attracted intensive attention. Recently, combining auto-encoder (AE) with graph neural networks (GNNs) has accomplished excellent performance by introducing structural information implied among data in clustering tasks. However, we observe that there are some limitations of most existing works: 1) in practical graph datasets, there exist some noisy or inaccurate connections among nodes, which would confuse network learning and cause biased representations, thus leading to unsatisfied clustering performance; 2) lacking dynamic information fusion module to carefully combine and refine the node attributes and the graph structural information to learn more consistent representations; and 3) failing to exploit the two separated views' information for generating a more robust target distribution. To solve these problems, we propose a novel method termed deep fusion clustering network with reliable structure preservation (DFCN-RSP). Specifically, the random walk mechanism is introduced to boost the reliability of the original graph structure by measuring localized structure similarities among nodes. It can simultaneously filter out noisy connections and supplement reliable connections in the original graph. Moreover, we provide a transformer-based graph auto-encoder (TGAE) that can use a self-attention mechanism with the localized structure similarity information to fine-tune the fused topology structure among nodes layer by layer. Furthermore, we provide a dynamic cross-modality fusion strategy to combine the representations learned from both TGAE and AE. Also, we design a triplet self-supervision strategy and a target distribution generation measure to explore the cross-modality information. The experimental results on five public benchmark datasets reflect that DFCN-RSP is more competitive than the state-of-the-art deep clustering algorithms. The corresponding code is available at https://github.com/gongleii/DFCN-RSP.

Multiple kernel clustering (MKC) aims to learn an optimal kernel to better serve for clustering from several precomputed basic kernels. Most MKC algorithms adhere to a common assumption that an optimal kernel is linearly combined by basic kernels. Based on a min-max framework, a newly proposed MKC method termed simple multiple kernel k -means (SimpleMKKM) can acquire a high-quality unified kernel. Although SimpleMKKM has achieved promising clustering performance, we observe that it cannot benefit from any prior knowledge. This would cause the learned partition matrix may seriously deviate from the expected one, especially in clustering tasks where the ground truth is absent during the learning course. To tackle this issue, we propose a novel algorithm termed regularized simple multiple kernel k -means with kernel average alignment (R-SMKKM-KAA). According to the experimental results of existing MKC algorithms, the average partition is a strong baseline to reflect true clustering. To gain knowledge from the average partition, we add the average alignment as a regularization term to prevent the learned unified partition from being far from the average partition. After that, we have designed an efficient solving algorithm to optimize the new resulting problem. In this way, both the incorporated prior knowledge and the combination of basic kernels are helpful to learn better unified partition. Consequently, the clustering performance can be significantly improved. Extensive experiments on nine common datasets have sufficiently demonstrated the effectiveness of incorporation of prior knowledge into SimpleMKKM.

Digital signatures are fundamental building blocks in various protocols to provide integrity and authenticity. The development of the quantum computing has raised concerns about the security guarantees afforded by classical signature schemes. CRYSTALS-Dilithium is an efficient post-quantum digital signature scheme based on lattice cryptography and has been selected as the primary algorithm for standardization by the National Institute of Standards and Technology. In this work, we present a high-throughput GPU implementation of Dilithium. For individual operations, we employ a range of computational and memory optimizations to overcome sequential constraints, reduce memory usage and IO latency, address bank conflicts, and mitigate pipeline stalls. This results in high and balanced compute throughput and memory throughput for each operation. In terms of concurrent task processing, we leverage task-level batching to fully utilize parallelism and implement a memory pool mechanism for rapid memory access. We propose a dynamic task scheduling mechanism to improve multiprocessor occupancy and significantly reduce execution time. Furthermore, we apply asynchronous computing and launch multiple streams to hide data transfer latencies and maximize the computing capabilities of both CPU and GPU. Across all three security levels, our GPU implementation achieves over 160× speedups for signing and over 80× speedups for verification on both commercial and server-grade GPUs. This achieves microsecond-level amortized execution times for each task, offering a high-throughput and quantum-resistant solution suitable for a wide array of applications in real systems.

With the rapid growth of Internet data volumes, Big Data analysis technologies have gradually permeated all aspects of life. However, the existence of data silos and the promulgation of relevant regulations make it challenging to apply these technologies. In this context, federated learning provides a feasible solution. Especially, XGBoost schemes for vertical federated learning have attracted much attention due to the widespread use of XGBoost. However, these schemes have limitations in terms of security or efficiency. To address these issues, we propose an efficient and privacy-preserving vertical federated learning framework based on the XGBoost algorithm, namely ELXGB, which achieves secure data alignment, XGboost training, and inference services. First, we design two node split algorithms based on homomorphic encryption and differential privacy, which securely and efficiently achieve tree node generation to construct the global model. Then, we utilize attribute obfuscation and direction obfuscation to achieve a secure inference algorithm, which avoids sensitive information leakage and protects the global model. Additionally, the global model of ELXGB is designed to be centralized, which does not require all participants to stay online for inference. Detailed security analysis demonstrates that ELXGB is privacy-preserving. Moreover, extensive experiments on real-world datasets indicate that ELXGB achieves high efficiency without sacrificing model accuracy.

In the past few years, numerous multi-view graph clustering algorithms have been proposed to enhance the clustering performance by exploring information from multiple views. Despite the superior performance, the high time and space expenditures limit their scalability. Accordingly, anchor graph learning has been introduced to alleviate the computational complexity. However, existing approaches can be further improved by the following considerations: (i) Existing anchor-based methods share the same number of anchors across views. This strategy violates the diversity and flexibility of multi-view data distribution. (ii) Searching for the optimal anchor number within hyper-parameters takes much extra tuning time, which makes existing methods impractical. (iii) How to flexibly fuse multi-view anchor graphs of diverse sizes has not been well explored in existing literature. To address the above issues, we propose a novel anchor-based method termed Flexible and Diverse Anchor Graph Fusion for Scalable Multi-view Clustering (FDAGF) in this paper. Instead of manually tuning optimal anchor with massive hyper-parameters, we propose to optimize the contribution weights of a group of pre-defined anchor numbers to avoid extra time expenditure among views. Most importantly, we propose a novel hybrid fusion strategy for multi-size anchor graphs with theoretical proof, which allows flexible and diverse anchor graph fusion. Then, an efficient linear optimization algorithm is proposed to solve the resultant problem. Comprehensive experimental results demonstrate the effectiveness and efficiency of our proposed framework. The source code is available at https://github.com/Jeaninezpp/FDAGF.

Multi-view clustering has gained broad attention owing to its capacity to exploit complementary information across multiple data views. Although existing methods demonstrate delightful clustering performance, most of them are of high time complexity and cannot handle large-scale data. Matrix factorization-based models are a representative of solving this problem. However, they assume that the views share a dimension-fixed consensus coefficient matrix and view-specific base matrices, limiting their representability. Moreover, a series of large-scale algorithms that bear one or more hyperparameters are impractical in real-world applications. To address the two issues, we propose an auto-weighted multi-view clustering (AWMVC) algorithm. Specifically, AWMVC first learns coefficient matrices from corresponding base matrices of different dimensions, then fuses them to obtain an optimal consensus matrix. By mapping original features into distinctive low-dimensional spaces, we can attain more comprehensive knowledge, thus obtaining better clustering results. Moreover, we design a six-step alternative optimization algorithm proven to be convergent theoretically. Also, AWMVC shows excellent performance on various benchmark datasets compared with existing ones. The code of AWMVC is publicly available at https://github.com/wanxinhang/AAAI-2023-AWMVC.

The trade-off between privacy and accuracy presents a challenge for current federated learning (FL) frameworks, hindering their progress from theory to application. The main issues with existing FL frameworks stem from a lack of interpretability and targeted privacy protections. To cope with these, we proposed Disentangled Federated Learning for Privacy (DFLP) which employes disentanglement, one of interpretability techniques, in private FL frameworks. Since sensitive properties are client-specific in nature, our main idea is to turn this feature into a tool that strikes the balance between data privacy and FL model performance, enabling the sensitive attributes to be private. DFLP disentangles the client-specific and class-invariant attributes to mask the sensitive attributes precisely. To our knowledge, this is the first work that successfully integrates disentanglement and the nature of sensitive attributes to achieve privacy protection while ensuring high FL model performance. Extensive experiments validate that disentanglement is an effective method for accuracy-aware privacy protection in FL frameworks.

Similarity range query over string sequences plays a significant role in bioinformatics, entity extraction, data mining and information retrieval. Meanwhile, with the popularity of cloud computing, a new paradigm is to outsource the similarity range query service to the cloud. However, existing solutions still have suffer from security and query efficiency drawbacks. To address these issues, we propose an efficient and private similarity range query scheme over encrypted string sequences. Specifically, we first organize string sequences into inverted index and design an inverted index based efficient similarity range query algorithm by applying several filter strategies. Second, based on public-key homomorphic encryption, we design a set of privacy-preserving protocols to protect the privacy of inverted index based range queries. Based on this, we propose a private and computationally efficient similarity range query scheme. Finally, we analyze the security of our scheme and conduct experiments to evaluate its performance, and the results indicate that our proposed scheme is computationally effective.

Improving the transferability of adversarial examples for the purpose of attacking unknown black-box models has been intensively studied. In particular, feature-level transfer-based attacks, which destroy the intermediate feature outputs of source models, are proven to generate more transferable adversarial examples. However, existing state-of-the-art feature-level attacks only destroy a single intermediate layer, this severely limits the transferability of adversarial examples. And all of these attacks have a vague distinction between positive and negative features. By contrast, we propose the Multi-layer Feature Division Attack (MFDA), which aggregates multi-layer feature information on the basis of feature division to attack. Extensive experimental evaluation demonstrates that MFDA can significantly boost the adversarial transferability and quantitatively distinguish the effects of positive and negative features on transferability. Compared to the state-of-the-art feature-level attacks, our improvement methods with MFDA increase the average success rate by 2.8% against normally trained models and 3.0% against adversarially trained models.

With the rapid development of machine learning, MLaaS has infiltrated into many fields such as image recognition, natural language processing, medical diagnosis, and so on. However, in MLaaS, data interaction between users and service providers is inevitable, and both users' private data and servers' model parameters are at risk of privacy disclosure. In order to solve this problem, homomorphic encryption is an extensively used technique to process private information over ciphertexts. However, since homomorphic encryption only supports linear operations, approximation techniques are required to calculate nonlinear functions, which leads to the loss of prediction accuracy and heavy computation overhead. Therefore, in this paper, we propose a secure neural network prediction scheme combining the trusted execution environment and homomorphic encryption with different security assumptions. Specifically, we first define the security model of TEE-assisted neural network prediction. Then, by combining a lightweight homomorphic encryption technique with TEE, we design secure neural network prediction protocols under different security levels, with which neural network prediction can be securely processed with high performance and accuracy. Finally, we evaluate the performance of our scheme on the MNIST, Fashion-MNIST, and KMNIST datasets, and the results demonstrate that our scheme indeed improves the prediction efficiency and accuracy compared to traditional homomorphic encryption-based schemes with polynomial approximation.

As an essential component part of the Intelligent Transportation System (ITS), the Internet of Vehicles (IoV) plays a vital role in alleviating traffic issues. Object detection is one of the key technologies in the IoV, which has been widely used to provide traffic management services by analyzing timely and sensitive vehicle-related information. However, the current object detection methods are mostly based on centralized deep training, that is, the sensitive data obtained by edge devices need to be uploaded to the server, which raises privacy concerns. To mitigate such privacy leakage, we first propose a federated learning-based framework, where well-trained local models are shared in the central server. However, since edge devices usually have limited computing power, plus a strict requirement of low latency in IoVs, we further propose a sparse training process on edge devices, which can effectively lighten the model, and ensure its training efficiency on edge devices, thereby reducing communication overheads. In addition, due to the diverse computing capabilities and dynamic environment, different sparsity rates are applied to edge devices. To further guarantee the performance, we propose, FedWeg, an improved aggregation scheme based on FedAvg, which is designed by the inverse ratio of sparsity rates. Experiments on the real-life dataset using YOLO show that the proposed scheme can achieve the required object detection rate while saving considerable communication costs.

Consistency plays an important role in learning theory. However, in multiple kernel clustering (MKC), the consistency of kernel weights has not been sufficiently investigated. In this work, we fill this gap with a non-asymptotic analysis on the consistency of kernel weights of a novel method termed SimpleMKKM. Under the assumptions of the eigenvalue gap, we give an infinity norm bound as $\widetilde{\mathcal{O}}(k/\sqrt{n})$, where $k$ is the number of clusters and $n$ is the number of samples. On this basis, we establish an upper bound for the excess clustering risk. Moreover, we study the difference of the kernel weights learned from $n$ samples and $r$ points sampled without replacement, and derive its upper bound as $\widetilde{\mathcal{O}}(k\cdot\sqrt{1/r-1/n})$. Based on the above results, we propose a novel strategy with Nyström method to enable SimpleMKKM to handle large-scale datasets with a theoretical learning guarantee. Finally, extensive experiments are conducted to verify the theoretical results and the effectiveness of the proposed large-scale strategy.

Since data outsourcing poses privacy concerns with data leakage, searchable symmetric encryption (SSE) has emerged as a powerful solution that enables clients to perform query operations on encrypted data while preserving their privacy. Dynamic SSE schemes have been proposed to handle update operations. However, it is shown that updates might increase the risk of information leakage. Meanwhile, to meet the requirement of real-world applications, it is desirable to have the searchable encryption scheme which supports both multiple clients and multi-keyword queries. To address these issues, this paper proposes MMDSSE, a multi-client forward secure dynamic SSE scheme that supports multi-keyword queries. MMDSSE allows the clients narrow down the results by providing an arbitrary subset of the entire archive, and thus suitable for cloud storage environment. Security analysis and experimental evaluations show that MMDSSE is secure and efficient.

Private Set Intersection (PSI) is one of the most important functions in secure multiparty computation (MPC). PSI protocols have been a practical cryptographic primitive and there are many privacy-preserving applications based on PSI protocols such as computing conversion of advertising and distributed computation. Private Set Intersection Cardinality (PSI-CA) is a useful variant of PSI protocol. PSI and PSI-CA allow several parties, each holding a private set, to jointly compute the intersection and cardinality, respectively without leaking any additional information. Nowadays, most PSI protocols mainly focus on two-party settings, while in multiparty settings, parties are able to share more valuable information and thus more desirable. On the other hand, with the advent of cloud computing, delegating computation to an untrusted server becomes an interesting problem. However, most existing delegated PSI protocols are unable to efficiently scale to multiple clients. In order to solve these problems, this paper proposes MDPPC, an efficient PSI protocol which supports scalable multiparty delegated PSI and PSI-CA operations. Security analysis shows that MDPPC is secure against semi-honest adversaries and it allows any number of colluding clients. For 15 parties with set size of 220on server side and 216on clients side, MDPPC costs only 81 seconds in PSI and 80 seconds in PSI-CA, respectively. The experimental results show that MDPPC has high scalability.

The rapid development of AI applications powered by deep learning in edge devices boosts the opportunity for real-time health monitoring. To address the potential privacy concern in the inference phase, homomorphic encryption (HE) is an alternative solution that encrypts inference data without exposing raw data and has several distinct advantages, (i.e., single-round communication, lightweight bandwidth consumption, and non-interactive computation). However, the computational overhead on the current HE-based privacy-preserving inference necessitates a substantial amount of time, which is not feasible for some real-time applications on edge devices. To address this issue, we propose CNN-guardian, a unified and compact neural network structure for real-time inference in HE-based inference on edge GPU. CNN-guardian designs a HE-friendly neural network and GPU engine that optimizes HE operations to accelerate the inference in the HE domain.

By encrypting the data of infected hosts, cryptographic ransomware has caused billions of dollars in financial losses to a wide range of victims. Many detection techniques have been proposed to counter ransomware threats over the past decade. Their common approach is to monitor I/O behaviors from user space and apply custom heuristics to discriminate ransomware. These techniques implicitly assume that ransomware behaves very differently from benign programs in terms of heuristics. However, when we investigated the behavior of benign and ransomware programs, we found that the boundary between their behaviors was blurred. A ransomware program can still achieve its goal even though it follows the behavior patterns of benign programs. In this paper, we aim to explore the limits of ransomware detection techniques that based on I/O behaviors. To this end, we present Animagus, an imitation-based ransomware attack that imitates behaviors of benign programs to disguise its encryption tasks. It first learns behavior patterns from a benign program, and then spawns and orchestrates child processes to perform encryption tasks behaving the same as the benign program. We evaluate its effectiveness against six state-of-the-art detection techniques, and the results show that it can successfully evade these defenses. We investigate in detail why they are ineffective and how Animagus is different from existing ransomware samples. In the end, we discuss potential countermeasures and the benefits that detection tools can gain from our work.

Website fingerprinting attack is an extensively studied technique used in a web browser to analyze traffic patterns and thus infer confidential information about users. Several website fingerprinting attacks based on machine learning and deep learning tend to use the most typical features to achieve a satisfactory performance of attacking rate. However, these attacks suffer from several practical implementation factors, such as a skillfully pre-processing step or a clean dataset. To defend against such attacks, random packet defense (RPD) with a high cost of excessive network overhead is usually applied. In this work, we first propose a practical filter-assisted attack against RPD, which can filter out the injected noises using the statistical characteristics of TCP/IP traffic. Then, we propose a list-assisted defensive mechanism to defend the proposed attack method. To achieve a configurable trade-off between the defense and the network overhead, we further improve the list-based defense by a traffic splitting mechanism, which can combat the mentioned attacks as well as save a considerable amount of network overhead. In the experiments, we collect real-life traffic patterns using three mainstream browsers, i.e., Microsoft Edge, Google Chrome, and Mozilla Firefox, and extensive results conducted on the closed and open-world datasets show the effectiveness of the proposed algorithms in terms of defense accuracy and network efficiency.

The Multi-receiver Encryption (MRE) scheme can meet the secure data transmission requirements in multicast and broadcast scenarios. To meet compliance, critical information infrastructure in China should be protected with Chinese national commercial cryptographic algorithms. Designing an MRE scheme based on Elliptic Curve Cryptography (ECC) is one of the current design methods with better flexibility and performance. However, the research on MRE schemes based on SM2 elliptic curve public-key cryptography is still in a blank state. This paper proposes a Certificateless SM2-based Multi-receiver Encryption (CL-SM2-MRE) scheme. We prove the security of the CL-SM2-MRE scheme under the Random Oracle Model (ROM) and analyze the performance.

Today's blockchain systems store detailed runtime information in the format of transactions and blocks, which are valuable not only to understand the finance of blockchain-based ecosystems but also to audit the security of on-chain applications. However, exploring this blockchain “big data” is challenging due to data heterogeneity and the huge amount. Existing blockchain exploration techniques are either incomplete or inefficient, making them inapt in time-sensitive applications. This paper presents ${\sf BlockExplorer}$ , an efficient and flexible blockchain exploration system for Ethereum. ${\sf BlockExplorer}$ builds on a master-slave architecture, where the master partitions all blocks into multiple non-overlapped sets and each slave simultaneously processes Ethereum big data based on a set of blocks. ${\sf BlockExplorer}$ implements a transaction-based partitioning approach to address load balance among slaves, and a code instrumentation approach to acquire complete Ethereum big data. The evaluation shows that ${\sf BlockExplorer}$ accelerates the data acquisition performance of the state-of-the-art by 4.1×, while the workload difference among slaves is up to 18%. To demonstrate the application of ${\sf BlockExplorer}$ , we develop three apps upon ${\sf BlockExplorer}$ to detect real-life attacks against Ethereum and show that our apps can detect attacks in a large range of blocks (e.g., ten million) within a short time (e.g., multiple hours).

Homomorphic encryption (HE), which allows computation over encrypted data, has often been used to preserve privacy. However, the computationally heavy nature and complexity of network topologies make the deployment of HE schemes in the Internet of Things (IoT) scenario difficult. In this work, we propose CARM, the first optimized GPU implementation that covers BGV, BFV and CKKS, targeting for accelerating homomorphic multiplication using GPU in heterogeneous IoT systems. Our solution is suitable for accelerating RNS homomorphic multiplication on both high-performance and embedded GPUs, as it is a parametric and generic design and offers various trade-offs between resource and efficiency. We offer constant-time low-level arithmetic with minimum instructions and memory usage, as well as performance- and memory-prior configurations. Through this, we can provide more real-time evaluation results and relieve the computational pressure on cloud devices. We deploy our implementations on two GPUs. Compared to the CPU implementation, we achieve up to$378.4\times$,$234.5\times$, and$287.2\times$speedup for homomorphic multiplication of BGV, BFV, and CKKS on Tesla V100S, and$8.8\times$,$9.2\times$, and$10.3\times$on Jetson AGX Xavier, respectively.

With the development of quantum computing, the existing cryptography schemes based on classical cryptographic primitives will no longer be secure. Hence, cryptographers are designing post-quantum cryptographic (PQC) schemes, and ideal lattice-based cryptography has emerged as a prime candidate. Today, as ideal lattice-based cryptography becomes more mature, its performance becomes an important optimization goal. In ideal lattice-based cryptography, polynomial arithmetic and polynomial sampling are the most time-consuming operations and therefore need to be accelerated. In this article, taking advantage of the parallelism of new 512-bit advanced vector instructions (AVX512), we present parallel implementations of polynomial arithmetic and polynomial sampling, thus comprehensively improving their performance. We conduct experiments with the Dilithium scheme(one scheme of NIST PQC Standardization Process Round-4). Our implementation gets a nice performance boost compared to its pure C language and 256-bit advanced vector instructions (AVX2) implementation.

The technique of packing multiple values into one message without losing homomorphic computation properties is the main workhorse that drives many exciting advances in applying lattice-based homomorphic encryption schemes to privacy-preserving Machine-Learning-as-a-Service (MLaaS). However, this technique does not directly work for the classic Paillier homomorphic encryption scheme, limiting the use of the Paillier scheme in the privacy-preserving MLaaS. To enrich the applications of Paillier in privacy-preserving MLaaS, we present a set of new methods for efficient linear computations over packed values under the Paillier scheme, such as vector multiplication, matrix multiplication, and convolutional calculation between ciphertexts and plaintexts. Different from the packing methods of lattice-based schemes, the Paillier packing method naturally allows higher packing capability for values in lower bit-length. This property can significantly benefit privacy-preserving MLaaS, as the values of user inputs and parameters of machine learning models are often quantized into low bits (e.g., 1-8 bits). We conduct comparisons based on different linear computation tasks, the proposed methods under the Paillier scheme clearly outperform the state-of-the-art in terms of communication and computational efficiency, especially in realistic scenarios. For example, compared to one of the recent arts CrypTFlow2 [1], the communication cost of our solution can be 21.7× smaller at best. Thanks to the reduction of communication cost, the runtime can be 2.46× faster than CrypTFlow2 at the median-country-speed of current global mobile broadband.

Fix pattern-based patch generation is a promising direction in automated program repair (APR). Notably, it has been demonstrated to produce more acceptable and correct patches than the patches obtained with mutation operators through genetic programming. The performance of pattern-based APR systems, however, depends on the fix ingredients mined from fix changes in development histories. Unfortunately, collecting a reliable set of bug fixes in repositories can be challenging. In this article, we propose investigating the possibility in an APR scenario of leveraging fix patterns inferred from code changes that address violations detected by static analysis tools. To that end, we build a fix pattern-based APR tool, Avatar , which exploits fix patterns of static analysis violations as ingredients for the patch generation of repairing semantic bugs. Evaluated on four benchmarks (i.e., Defects4J, Bugs.jar, BEARS, and QuixBugs), Avatar presents the potential feasibility of fixing semantic bugs with the fix patterns inferred from the patches for fixing static analysis violations and can correctly fix 26 semantic bugs when Avatar is implemented with the normal program repair pipeline. We also find that Avatar achieves performance metrics that are comparable to that of the closely related approaches in the literature. Compared with CoCoNut, Avatar can fix 18 new bugs in Defects4J and 3 new bugs in QuixBugs. When compared with HDRepair, JAID, and SketchFix, Avatar can newly fix 14 Defects4J bugs. In terms of the number of correctly fixed bugs, Avatar is also comparable to the program repair tools with the normal fault localization setting and presents better performance than most program repair tools. These results imply that Avatar is complementary to current program repair approaches. We further uncover that Avatar can present different bug-fixing performances when it is configured with different fault localization tools, and the stack trace information from the failed executions of test cases can be exploited to improve the bug-fixing performance of Avatar by fixing more bugs with fewer generated patch candidates. Overall, our study highlights the relevance of static bug-finding tools as indirect contributors of fix ingredients for addressing code defects identified with functional test cases (i.e., dynamic information).

Tree-based models are wildly adopted in various real-world scenarios. Recently, there is a growing interest in vertical federated tree-based model learning to build tree-based models by exploiting data from multiple organizations without violating data privacy regulations. However, most existing work focuses on batch learning settings where all training samples are prepared at once. They cannot be applied to scenarios where local samples come in a streaming manner. Additionally, the present federated learning algorithms suffer from inference attacks. In this paper, we present a novel solution that enables different organizations to jointly train a tree-based model in an incremental and privacy-preserving manner. Our solution is based on Very Fast Decision Tree (VFDT) for incrementally building a tree model. Since data statistics exchanged in the training process may implicitly disclose private information, we propose a protection mechanism based on order-preserving encryption. To further improve the efficiency of the solution, we compress the size of statistics by means of regional counting, which not only maintains model accuracy but also enhances privacy. We conduct extensive experiments on various real-world datasets and the results show the superiority of our solution in terms of both efficiency and privacy.

Internet of Things (IoT) is increasingly being used in real life, especially in the eHealthcare field. Among eHealthcare, the application of predicting patients' health status based on their daily activity data which is collected by IoT equipment has attracted extensive attentions and researches. In this application, patients' data which are treated as time-series data are transmitted to healthcare center (HC), then HC makes predictions based on an established classification model. However, making predictions using classification models requires a lot of computing resources, while HC usually cannot afford such numerous calculations. The use of the cloud solves the problem of insufficient computing resources, but it causes another problem, namely the leakage of user privacy. In particular, not only patients' data leak patients' privacy information, the classification model also causes the privacy disclosure of patients and HC. We design a new system model and propose an algorithm which can protect patients' data and classification model from leakage and offload calculation to multiple clouds. Our algorithm can better protect privacy of patients and HC in more complex classification scene, and can effectively reduce the computational cost of the healthcare center

Browser APIs are essential to the modern web experience. Due to their large number and complexity, they vastly expand the attack surface of browsers. To detect vulnerabilities in these APIs, fuzzers generate test cases with a large amount of random API invocations. However, the massive search space formed by arbitrary API combinations hinders their effectiveness: since randomly-picked API invocations unlikely interfere with each other (i.e., compute on partially shared data), few interesting API interactions are explored. Consequently, reducing the search space by revealing inter-API relations is a major challenge in browser fuzzing.

Taint analysis assists fuzzers in solving complex fuzzing constraints by inferring the influencing input bytes. Execution paths in real-world programs often reach loops, where constraints in these loops can be visited and recorded multiple times. Conventional taint analysis techniques experience difficulties when distinguishing between multiple occurrences of the same constraint. In this paper, we propose PATA, a fuzzer that implements path-aware taint analysis, i.e. one that distinguishes between multiple occurrences of the same variable based on the execution path information. PATA does so using the following steps. First, PATA identifies variables used in constraints and constructs the Representative Variable Sequence (RVS), consisting of occurrences of all representative constraint variables and their values. Next, PATA perturbs the input, matches its RVS with that of the original input, and looks for value changes to identify the influencing input bytes for each entry in the RVS. Finally, PATA mutates the corresponding input bytes to solve constraints in the given path. To demonstrate the effectiveness of PATA over conventional taint analysis methods, we evaluated its performance on the benchmarks Google’s fuzzer-test-suite and LAVA-M against AFL, MOPT, TortoriseFuzz, VUzzer, Angora, Redqueen, and Greyone. On Google’s fuzzer-test-suite, PATA outperformed these state-of-the-art fuzzers by 29%–1830% and 7%–87% in the number of unique paths found and basic blocks covered, respectively. More importantly, it found more bugs than the comparison fuzzers, including 17 unlisted ones. On LAVA-M, PATA performed the best out of all evaluated fuzzers and found 2602 bugs. On open-source projects, PATA found 40 previously unknown bugs, with 12 of them confirmed as CVEs.

Federated Learning (FL) is a framework where multiple parties can train a model jointly without sharing private data. Private information protection is a critical problem in FL. However, the communication overheads of existing solutions are too heavy for IoT devices in resource-constrained environments. Additionally, they cannot ensure robustness when IoT devices become offline. In this paper, Democratic Federated Learning (DemoFL) is proposed, which is a privacy-preserving FL framework that has sufficiently low communication overheads. DemoFL involves a consensus module to ensure the system is robust. It also utilizes a tree structure to reduce the time communication overheads and realizes high robustness without reducing accuracy. The proposed algorithm reduces the communication complexity of aggregation at training by M $M$ times, M $M$ being a controllable parameter. Sufficient experiments have been conducted to evaluate the efficiency of the proposed method. The experimental results also demonstrate the practicality of the proposed framework for IoT devices in unstable environments.

The supervisory control and data acquisition (SCADA) system is widely used in industrial control and the contemporary Industrial Internet of Things (IIoT). Unfortunately, due to its relatively weak design in terms of data security and access control, SCADA systems are becoming a favorite target for attackers. End-to-end encryption, such as SSL/TLS protocol, is used to protect the data transmission, but it cannot guarantee security in third-party cloud platforms. In this article, we propose a secure revocable fine-grained access control and data sharing scheme. This scheme not only ensures the confidentiality of the data but also enhances the access control of the SCADA system. Our scheme is based on three key observations. The common communication architecture of SCADA systems cannot protect data security itself. The security supports provided by industrial control protocols are limited. Moreover, the third-party cloud platforms are semitrusted. In addition, we have introduced digital signature technology to assure the integrity of the data in the SCADA system. We prove that our scheme is secure. This scheme has been experimentally evaluated to introduce negligible performance losses while improving data security in the SCADA system.

White-box block cipher (WBC) has been proposed by Chow \textit{et al.} to prevent the secret key to be extracted from its implementation in an untrusted context. A pivotal technique behind WBC is to convert the iterated round functions into a series of look-up tables (LUTs) with encodings. The construction of encoded LUTs consists of matrix operations, such as multiplication and inversion. The widely-used matrix libraries in applications, such as open-source NTL and M4RI, are primarily designed for large dimensional matrix operations. Therefore, they might not be suitable for WBC implementations which are mainly based on small-scale matrices and vectors. In this paper, we propose a new matrix library named WBMatrix for the optimization of WBC implementations. WBMatrix reduces the operating steps of multiplication and simultaneously generates pairwise invertible matrices as encodings. The performance comparison supports that WBMatrix improves the table construction and encryption phases on Intel x86 and ARMv8 platforms. Moreover, WBMatrix also boosts the initialization and encryption phases of LowMC/LowMC-M block ciphers and enhances the performance for the generation of key-dependent Sbox.

Thanks to relatively small public and secret keys, the Supersingular Isogeny Key Encapsulation (SIKE) protocol made it into the third evaluation round of the post-quantum standardization project of the National Institute of Standards and Technology (NIST). Even though a large body of research has been devoted to the efficient implementation of SIKE, its latency is still undesirably long for many real-world applications. Most existing implementations of the SIKE protocol use the Montgomery representation for the underlying field arithmetic since the corresponding reduction algorithm is considered the fastest method for performing multiple-precision modular reduction. In this paper, we propose a new data representation for supersingular isogeny-based Elliptic-Curve Cryptography (ECC), of which SIKE is a sub-class. This new representation enables significantly faster implementations of modular reduction than the Montgomery reduction, and also other finite-field arithmetic operations used in ECC can benefit from our data representation. We implemented all arithmetic operations in C using the proposed representation such that they have constant execution time and integrated them to the latest version of the SIKE software library. Using four different parameters sets, we benchmarked our design and the optimized generic implementation on a 2.6 GHz Intel Xeon E5-2690 processor. Our results show that, for the prime of SIKEp751, the proposed reduction algorithm is approximately 2.61 times faster than the currently best implementation of Montgomery reduction, and our representation also enables significantly better timings for other finite-field operations. Due to these improvements, we were able to achieve a speed-up by a factor of about 1.65, 2.03, 1.61, and 1.48 for SIKEp751, SIKEp610, SIKEp503, and SIKEp434, respectively, compared to state-of-the-art generic implementations.

Saber is a module-lattice-based key encapsulation scheme that has been selected as a finalist in the NIST Post-Quantum Cryptography standardization project. As Saber computes on considerably large matrices and vectors of polynomials, its efficient implementation on memory-constrained IoT devices is very challenging. In this paper, we present an implementation of Saber with a minor tweak to the original Saber protocol for achieving reduced memory consumption and better performance. We call this tweaked implementation ‘Saber+’, and the difference compared to Saber is that we use different generation methods of public matrix$\boldsymbol{A}$and secret vector$\boldsymbol{s}$for memory optimization. Our highly optimized software implementation of Saber+ on a memory-constrained RISC-V platform achieves 48% performance improvement compared with the best state-of-the-art memory-optimized implementation of original Saber. Specifically, we present various memory and performance optimizations for Saber+ on a memory-constrained RISC-V microcontroller, with merely 16KB of memory available. We utilize the Number Theoretic Transform (NTT) to speed up the polynomial multiplication in Saber+. For optimizing cycle counts and memory consumption during NTT, we carefully compare the efficiency of the complete and incomplete-NTTs, with platform-specific optimization. We implement 4-layers merging in the complete-NTT and 3-layers merging in the 6-layer incomplete-NTT. An improved on-the-fly generation strategy of the public matrix and secret vector in Saber+ results in low memory footprint. Furthermore, by combining different optimization strategies, various time-memory trade-offs are explored. Our software implementation for Saber+ on selected RISC-V core takes just 3,809K, 3,594K, and 3,193K clock cycles for key generation, encapsulation, and decapsulation, respectively, while consuming only 4.8KB of stack at most.

With the popularity of cloud storage services, people are increasingly accustomed to storing images in the cloud. However, cloud storage services raise privacy concerns, e.g., leakage of images to unauthorized third parties and service providers may exploit image detection technologies to portrait users without permission. Although privacy concerns can be solved by encrypting images before they are uploaded to the cloud, traditional encryption methods significantly affect the usability and user experience, for example, users cannot preview images in the cloud. Recently, Marohnet al.proposed two approximate thumbnail-preserving encryption schemes, called DRPE and TPE-LSB, to balance the privacy and usability of images in the cloud. However, both schemes have defects that either the decryption may fail or the ciphertext images have poor performance in perceived quality and too many noise points after decryption. To this end, we pertinently propose a high-fidelity thumbnail-preserving encryption scheme (HF-TPE). Compared with the previous works, on the one hand, the HF-TPE scheme not only ensures the correct decryption of ciphertext images, but also makes the ciphertext thumbnails more close to the plaintext images perceptually. On the other hand, the decrypted thumbnails have lower noise intensity and upper limit of the number of noises. In addition, simulation experiments further show that the HF-TPE scheme can guarantee users’ usability.

Mobile payment system has been expected to provide more efficient and convenient payment methods. However, compared to traditional payments, mobile payment issues related to the security of electronic accounts and payment apps present serious challenges. In this paper, we find the potential security risks by analyzing the commonly used tokenized mobile payment method and put forward the corresponding off-site attack strategy. In this scenario, the attackers are not only limited to malicious third parties but also can be illegal merchants. To address the off-site attack, especially the potential attackers who may be malicious merchants, we also propose SALP, a secure and authenticated payment protocol, using time and position as necessary conditions for the payment confirmation. Furthermore, we leverage identity-based signature (IBS) to prevent altering the information and reduce the overhead of the third-party authentication. We conduct case studies to demonstrate that the SALP can effectively prevent the off-site payment attack without a trusted hardware environment. In particular, we finally argue that SALP does not bring additional system overhead without degrading the convenience of mobile payment.

Cloud computing enables enterprises and individuals to outsource and share their data. This way, cloud computing eliminates the heavy workload of local information infrastructure. Attribute-based encryption has become a promising solution for encrypted data access control in clouds due to the ability to achieve one-to-many encrypted data sharing. Revocation is a critical requirement for encrypted data access control systems. After outsourcing the encrypted attribute-based ciphertext to the cloud, the data owner may want to revoke some recipients that were authorized previously, which means that the outsourced attribute-based ciphertext needs to be updated to a new one that is under the revoked policy. The integrity issue arises when the revocation is executed. When a new ciphertext with the revoked access policy is generated by the cloud server, the data recipient cannot be sure that the newly generated ciphertext guarantees to be decrypted to the same plaintext as the originally encrypted data, since the cloud server is provided by a third party, which is not fully trusted. In this article, we consider a new security requirement for the revocable attribute-based encryption schemes: integrity. We introduce a formal definition and security model for the revocable attribute-based encryption with data integrity protection (RABE-DI). Then, we propose a concrete RABE-DI scheme and prove its confidentiality and integrity under the defined security model. Finally, we present an implementation result and provide performance evaluation which shows that our scheme is efficient and practical.

To manage outsourced encrypted data sharing in clouds, attribute-based proxy re-encryption (ABPRE) has become an elegant primitive. In ABPRE, a cloud server can transform an original recipient’s ciphertext to a new one of a shared user’s. As the transformation is computation consuming, a malicious cloud server may return an incorrect re-encrypted ciphertext to save its computation resources. Moreover, a shared user may accuse the cloud server of returning an incorrect re-encrypted ciphertext to refuse to pay the cost of using the cloud service. However, existing ABPRE schemes do not support a mechanism to achieve verifiability and fairness. In this article, a novel verifiable and fair attribute-based proxy re-encryption (VF-ABPRE) scheme is introduced to support verifiability and fairness. The verifiability enables a shared user to verify whether the re-encrypted ciphertext returned by the server is correct and the fairness ensures a cloud server escape from malicious accusation if it has indeed conducted the re-encryption operation honestly. Additionally, we conduct a performance experiment to show the efficiency and practicality of the new VF-ABPRE scheme.

With the explosive growth of user data, recommenders have become increasingly complicated. State-of-the-art algorithms often have high computational complexity and heavily use non-linear transformations. This fact makes the privacy-preserving problem more challenging, despite the significant advances in cryptography. To alleviate this problem, we propose a privacy-friendly recommender, CryptoRec. It only relies on additions and multiplications, which are efficiently supported by most cryptographic primitives. Different from others, in CryptoRec, the parameter space only contains item features (user features can be directly computed from the item features). This property allows CryptoRec to, (1) naturally achieve transferability if two datasets share the same item entries, which can benefit differential privacy protection; (2) directly estimate the preference of new users whose data is not included in the training set, drastically improving recommendation efficiency. We first evaluate CryptoRec on three real-world datasets. The evaluation results show that the accuracy is competitive with state-of-the-art. Then, we build differential privacy into CryptoRec and leverage its transferability property to reduce the overall privacy loss. Lastly, we demonstrate the simplicity and efficiency of using CryptoRec to construct secure recommendation protocols based on homomorphic encryption schemes. Our results show that CryptoRec outperforms existing solutions in terms of both accuracy and efficiency.

Driven by artificial intelligence and computer vision industries, Graphics Processing Units (GPUs) are now rapidly achieving extraordinary computing power. In particular, the NVIDIA Tegra K1/X1/X2 embedded GPU platforms, which are also treated as edge computing devices, are now widely used in embedded environments such as mobile phones, game consoles, and vehicle-mounted systems to support high-dimension display, auto-pilot, and so on. Meanwhile, with the rise of the Internet of Things (IoT), the demand for cryptographic operations for secure communications and authentications between edge computing nodes and IoT devices is also expanding. In this contribution, instead of the conventional implementations based on FPGA, ASIC, and ARM CPUs, we provide an alternative solution for cryptographic implementation on embedded GPU devices. Targeting the new cipher suite added in TLS 1.3, we implement Edwards25519/448 and Curve25519/448 on an edge computing platform, embedded GPU NVIDIA Tegra X2, where various performance optimizations are customized for the target platform, including a novel parallel method for the register-limited embedded GPUs. With about 15 W of power consumption, it can provide 210k/31k ops/s of Curve25519/448 scalar multiplication, 834k/123k ops/s of fixed-point Edwards25519/448 scalar multiplication, and 150k/22k ops/s of unknown-point one, which are respectively the primitives and main workloads of key agreement, signature generation, and verification of the TLS 1.3 protocol. Our implementations achieve 8 to 26 times speedup of OpenSSL running in the very powerful ARM CPU of the same platform and outperform the state-of-the-art implementations in FPGA by a wide margin with better power efficiency.

Over the past years, the increasingly severe data island problem has spawned an emerging distributed deep learning framework—federated learning, in which the global model can be constructed over multiple participants without directly sharing their raw data. Despite its promising prospect, there are still many security challenges in federated learning, such as privacy preservation and integrity verification. Furthermore, federated learning is usually performed with the assistance of a center, which is prone to cause trust worries and communicational bottlenecks. To tackle these challenges, in this paper, we propose a privacy-preserving and verifiable decentralized federated learning framework, named PVD-FL, which can achieve secure deep learning model training under a decentralized architecture. Specifically, we first design an efficient and verifiable cipher-based matrix multiplication (EVCM) algorithm to execute the most basic calculation in deep learning. Then, by employing EVCM, we design a suite of decentralized algorithms to construct the PVD-FL framework, which ensures the confidentiality of both global model and local update and the verification of every training step. Detailed security analysis shows that PVD-FL can well protect privacy against various inference attacks and guarantee training integrity. In addition, the extensive experiments on real-world datasets also demonstrate that PVD-FL can achieve lossless accuracy and practical performance.

The effectiveness of state-of-the-art deep learning (DL) models has empowered the development of industrial Internet of things (IIoT). Recently, considering resource-constrained and privacy-required IIoT devices, collaborative inference has been proposed, which splits DL models and deploys them in IIoT devices and an edge server separately. However, in this article, we argue that there are still severe privacy vulnerabilities in collaborative inference systems. And we devise the first membership inference attack (MIA) against collaborative inference, to infer whether a particular data sample is used for training the model of IIoT systems. Existing MIAs either assume full access to the systems’ APIs or availability of the target model's parameters, which is not applicable in realistic IIoT environments. In contrast to prior works, we proposetransfer-inheritshadow learning and thus relax these key assumptions. We evaluate our attack on different datasets and various settings, and the results show it has high effectiveness.

Distance-bounding (DB) protocols are used to verify the physical proximity of two devices. DB can be used to establish trusted ad-hoc connections in the industrial Internet-of-Things, e.g., nodes can verify they are deployed in the same location and monitoring the same piece of equipment. Thresholds and error correction codes (ECCs) are two methods to provide error-resilience for DB protocols working in noisy environments. However, the threshold method adds overheads and the ECC method increases the adversary success probability, compared to threshold, when implemented in precommitment DB protocols. In this article, we investigate the ECC method and demonstrate that designers can mitigate increased adversary success probability by using nonsystematic codes. To demonstrate this idea, we compare a prominent precommitment protocol by Brands and Chaum (BC) integrated with different types of ECCs with two existing error-resilience methods, showing how nonsystematic codes provide improved protocol security. Moreover, We further evaluate the BC protocol with nonsystematic ECCs and discuss how to configure protocols to minimize the protocol failure rate, while maintaining adequate attack success probability.

In recent years, researchers have made a great success on the automatic classification and detection of malware utilizing machine learning methods. However, most machine learning based approaches over rely on the training samples such that a new malware family not belonging to the training set cannot be identified. To address such issue, we propose a soft relevance value (s-value), a new evaluating way of feature soft relevance that uses the mixed distance criterion to assess classified results. Specifically, we leverage the mixed distance criterion from pattern recognition to distinguish testing samples as a new family which is not labeled in training set. Finally, we evaluate hows-value can be used to distinguish and classify a new malware family with the malware datasets from the Research Prediction Competition of Microsoft Malware Classification Challenge and Windows (Kaggle). The experimental results show that, the train-ing time is approximately 12 hours, while the prediction time is only ∼0.5 second. Comparing against the Kaggle winner, our time costs for training and pprediction only occupy 16.7% and 3.8% of the winner.s time costs, respectively. The accuracy of classifying malware reaches 99.8%. Such results indicates that our proposeds-value achieves a balance in accuracy, training and prediction time, and outperforms the state-of-the-art machine learning based malware detection approaches. Besides, our method is able to identify new malware families that are not included in the training set.

Recently, Zhanget al.proposed a lattice-based data outsourcing scheme with public integrity verification (DOPIV), which enables an original data owner to delegate a proxy to generate the signatures of data and outsource them to the cloud server. They employed a third party auditor (TPA) to check the integrity of the outsourced data and any TPA can verify the data integrity efficiently. DOPIV is claimed to achieve proxy-oriented secure data outsourcing as well as storage correctness guarantee. Unfortunately, we find that there exist vulnerabilities in DOPIV which allow the cloud server to simply delete the received data without being noticed by the TPA. Fortunately, we come up with a simple and efficient solution to thwart the proposed attack. Our improved scheme maintains all the features claimed in DOPIV.

The rapid development of in-vehicle networks and protocols brings efficient communication service but also increases the risk of attack. Any vulnerability may be leveraged to cause serious consequences. It is of vital importance to guarantee their security. However, the vulnerability detection efficiency of traditional techniques such as fuzzing is challenged by the complex relations among protocol states.In this paper, we propose PAVFuzz, a state-sensitive fuzz testing framework to secure those protocols used in autonomous vehicles. It automatically learns relations between two data elements in different protocol states. The relations will then be used to calculate and update the mutation weight of each data element continuously. Accordingly, PAVFuzz is able to select the target data elements and perform state-sensitive mutation to boost the efficiency. Experiments show that, compared with state-of-the-art fuzzers Peach and AFL, PAVFuzz increases branch coverage by averagely 22.51% and 369.19% within 24 hours. It has successfully exposed 12 serious previously unknown vulnerabilities among several protocols that are widely used in autonomous vehicles, such as RTPS and SOME/IP. We have reported them to the developers and corresponding patches have been released.

The rapid development of the Internet of Things (IoT) has brought challenges to IoT platforms for high-efficiency deployments and low-budget management. Identifying IoT devices is the prerequisite for monitoring, protecting, and managing them. Considering different providers and IoT device renovation, centralized device identification solutions require large amounts of training data and frequent model updates. Traditional solutions based on machine learning cannot preserve identification precision for the long term at a low cost in reality. In this paper, we propose a multi-level IoT device identification framework, alleviating the problem of novel class detection and large-scale updating of IoT models in IoT device identification. The proposed framework improves the usability of device identification technology in the real world. We also designed an IoT device identification method, achieving an average identification accuracy of 93.37 %. With this proposed multi-level IoT device identification framework, IoT device identification can achieve a high precision over a long time.

Kyber, an IND-CCA-secure key encapsulation mechanism (KEM) based on the MLWE problem, has been shortlisted for the third round evaluation of the NIST Post-Quantum Cryptography Standardization. In this paper, we explored the optimizations of Kyber in high-performance processors from the ARM Cortex-A series, which are widely used in mainstream mobile phones. To improve the performance of Kyber, we utilized the powerful SIMD instruction set NEON in an ARMv8-A to parallelize the core modules of Kyber, i.e., modular reduction and NTT. Specifically, we specially designed the optimized implementation based on the characteristic of the NEON instruction set for the Barrett and Montgomery reduction algorithms. To make full use of the computing power of NEON instructions, we proposed a novel strategy for computing the 16-bit Barrett reduction without handling the 32-bit intermediate result. Our Barrett and Montgomery reduction showed 8.52 and 8.89 times faster than the reference implementation. As for NTT/INTT, we adopted the 2+5 layer merging strategy on an ARMv8-A to implement NTT/INTT after carefully analyzing the register occupancy of various layer merging techniques. Thanks to the selected layer merging strategy, our NTT and INTT achieved 11.89 and 13.45 times speedups compared with the reference implementation. Our optimized software achieved 1.77×, 1.85×, and 2.16× speedups for key generation, encapsulation, and decapsulation compared with Kyber's reference implementation.

Fault localization produces bug positions as the basic input for many automated program repair (APR) systems. Given that test cases are the common means that automatic fault localization techniques leverage, we investigate the impact of their characteristics (in terms of quality and quantity) on APR. In particular, we analyze the statements that appear in crash stack traces when test cases fail (note that stack traces are available when an ordinary test case fails since its verdict is often made by assertions that produce errors such as AssertError in Java and JUnit), and explore the possibility of using some relevant crash information to enhance fault localization; this ultimately improves the effectiveness of APR tools. Our study reveals that the considered state-of-the-art APR systems achieve the best performance when fixing bugs associated with boolean type expected values (e.g., assertTrue ()) or assertFalse(). In contrast, they achieve their worst performance when addressing bugs related to null check assertions. Meanwhile, null check bugs as well as the bugs associated with boolean and string type expected values are still the main challenge that should be addressed by the future APR. For exception throwing bugs, existing APR systems present the best performance on fixing NullPointerException bugs, while the tough task of them is to resolve the bugs throwing developer-defined exceptions. The information in stack traces after executing the bug-triggering test cases can be used to effectively improve the performance on fault localization and program repair.

With the boom of Initial Coin Offerings (ICO) in the financial markets, smart contracts have gained rapid popularity among consumers. Smart contract vulnerabilities however made them a prime target to malicious attacks that are leading to huge losses. The research community is thus applying various software engineering technologies to smart contracts to address them. In general, to detect vulnerabilities in smart contracts, mutation and fuzz based testing approaches have been widely studied and indeed achieved promising performance on benchmark datasets. Generating test inputs with mutation approaches essentially relies on the available test cases in a smart contract program. In our preliminary study, however, we observed that 56.4% of 218 identified open-source smart contract project repositories do not provide any test case for validation. Fuzzing test inputs leads to random values and lacks practical usefulness. Our work addresses this problem: we propose an approach, Smartgift, which generates practical inputs for testing smart contracts by learning from the transaction records of real-world smart contracts. Leveraging a collected set of over 60 thousand transaction records, Smartgift is able to generate relevant test inputs for ~77% smart contract functions, largely outperforming the traditional fuzzing approach (successful for only 60% functions). We further demonstrate the practicality of the test inputs by using them to replace the test inputs of the ContractFuzzer state of the art smart contract vulnerability detector: with inputs by Smartgift, ContractFuzzer can now detect 131 of the 154 vulnerabilities in its benchmark.

Software supply chain security has now become a critical concern in the software industry (and beyond) following the large impact of recent attacks: hackers injected malicious code into Solarwinds components and Octopus scanner, which eventually infected a wide range of downstream dependencies, affecting a massive number of users. Since supply chain vulnera-bilities are a well-known concern, especially with open source systems, approaches in the literature mainly focus on identifying and patching such vulnerability. Frequently, however, a vulnerability patch is not immediately propagated to earlier releases that have been inherited by dependents, leaving residual vulnerabilities in supply chains. Our work addresses this challenge and develops a simple approach to iteratively explore the attack surface of supply chain residual vulnerabilities in open source projects. We have assessed our search scheme on 50 GitHub-hosted projects having high stars and forks: we mine their bug fix commits and identify buggy package versions to track the affected dependents and estimate the potential attack surface. We find that many projects fix their vulnerable issues by update their dependency versions, and version inheritance is a significant cause of supply chain attacks for open source projects.

Deep learning makes the Internet-of-Things (IoT) devices more attractive, and in turn, IoT facilitates the resolution of the contradiction between data collection and privacy concerns. IoT devices with small-scale computing power can contribute to model training without sharing data in collaborative learning. However, collaborative learning is susceptible to generative adversarial network (GAN) attack, where an adversary can pretend to be a participant engaging in the model training and learn other participants' data. In this article, we propose a secure collaborative deep learning model which resists GAN attacks. We isolate the participants from the model parameters, and realize the local model training of participants via the interaction mode, ensuring that neither the participants nor the server would have access to each other's data. In particular, we target convolutional neural networks, the most popular network, design specific algorithms for various functionalities in different layers of the network, making it suitable for deep learning environments. To our best knowledge, this is the first work designing specific protocol against GAN attacks in collaborative learning. The results of our experiments on two real data sets show that our protocol can achieve good accuracy, efficiency, and image processing adaptability.

Cloud computing has become prevalent due to its nature of massive storage and vast computing capabilities. Ensuring a secure data sharing is critical to cloud applications. Recently, a number of identity-based broadcast proxy re-encryption (IB-BPRE) schemes have been proposed to resolve the problem. However, the IB-BPRE requires a cloud user (Alice) who wants to share data with a bunch of other users (e.g., colleagues) to participate the group shared key renewal process because Alice's private key is a prerequisite for shared key generation. This, however, does not leverage the benefit of cloud computing and causes the inconvenience for cloud users. Therefore, a novel security notion named revocable identity-based broadcast proxy re-encryption (RIB-BPRE) is presented to address the issue of key revocation in this work. In a RIB-BPRE scheme, a proxy can revoke a set of delegates, designated by the delegator, from the re-encryption key. The performance evaluation reveals that the proposed scheme is efficient and practical.

The emergence of cloud infrastructure has significantly reduced the costs of hardware and software resources in computing infrastructure. To ensure security, the data is usually encrypted before it's outsourced to the cloud. Unlike searching and sharing the plain data, it is challenging to search and share the data after encryption. Nevertheless, it is a critical task for the cloud service provider as the users expect the cloud to conduct a quick search and return the result without losing data confidentiality. To overcome these problems, we propose a ciphertext-policy attribute-based mechanism with keyword search and data sharing (CPAB-KSDS) for encrypted cloud data. The proposed solution not only supports attribute-based keyword search but also enables attribute-based data sharing at the same time, which is in contrast to the existing solutions that only support either one of two features. Additionally, the keyword in our scheme can be updated during the sharing phase without interacting with the PKG. In this article, we describe the notion of CPAB-KSDS as well as its security model. Besides, we propose a concrete scheme and prove that it is against chosen ciphertext attack and chosen keyword attack secure in the random oracle model. Finally, the proposed construction is demonstrated practical and efficient in the performance and property comparison.

Botmasters generate a large number of malicious algorithmically generated domains (mAGDs) through domain generation algorithms (DGAs) to infect a large number of hosts on a network, which creates inconvenience in people's network lives. The workload of detecting mAGDs by collecting the responses of the domain name system (DNS) is considerable. In this article, we propose a system named the automatic NXDomain classification system (ANCS) that can automatically identify and classify the nonexistent domain (NXD) as benign or malicious by studying the features extracted from benign NXDs (bNXDs) and mAGDs. The ANCS uses online, incremental, and fuzzy rough sets machine learning to improve the time, memory, false positive rate, false negative rate, and accuracy of the detection process. First, an online and incremental algorithm can reduce the training time. Second, the addition of fuzzy rough sets can dynamically adjust the degree of the membership function, optimizing the weight distribution of each feature, and further, improving the classification accuracy. The experimental evaluation shows that the ANCS can reach a very high classification accuracy at a low false positive rate and a low false negative rate, which has good practicability. Moreover, both time and memory are well guaranteed, and the ANCS also has good generalization performance, making up for sensitive points of noisy samples and the lack of nonincremental machine learning.

Low Entropy Masking Schemes (LEMS) had been proposed to mitigate the high-performance overhead results from the Full Entropy Masking Schemes (FEMS) while offering good protection against side-channel attacks. The masking schemes usually rely on Boolean masking, however, splitting sensitive variables in a multiplicative way is more amenable to non-linear functions and it had been applied to both software and hardware with a competitive alternative to state-of-the-art masked design. Compared to the comprehensive analysis done for Boolean LEMS, the specific leakage characteristics of Multiplicative LEMS have not yet been analyzed. In this paper, we introduce security models for LEMS to characterize the balance of the mask set. Based on the security model, we present an inherent weakness of Multiplicative LEMS. We prove that this defect of Multiplicative LEMS cannot be compensated by choosing a proper mask set, and the security of FEMS is guaranteed thanks to the Dirac function which is used to resist zero-value attack. Then, we exhibit the leakages in the implementation of Multiplicative LEMS. In particular, we propose a new attack against Multiplicative LEMS more efficient by utilizing the distribution of masked intermediate values. The feasibility of the attack is verified by both simulation and practical experiments.

The application of the Internet of Things (IoT) in medical field has brought unprecedented convenience to human beings. However, attackers can use device configuration vulnerabilities to hijack devices, control services, steal medical data, or make devices operate illegally. These restrictions have led to huge security risks for IoT, and have challenged the management of critical infrastructure services. Based on these problems, this article proposes an anomaly detection system for detecting illegal behavior (DIB) in medical IoT environment.The DIB system can analyze data packets transmitted by medical IoT devices, learn operation rules by itself, and remind management personnel that the device is in an abnormal operation state to ensure the safety of control service. We further propose a model that is based on rough set theory and fuzzy core vector machine (FCVM) to improve the accuracy of DIB classification anomalies. Experimental results show that the R-FCVM is effective.

The sensing-as-a-service (SaaS) model has been explored to address the challenge of intractability of managing a large number of sensors faced by future smart cities. However, how to effectively share sensor data without compromising confidentiality, privacy protection, and fair trading without third parties is one of critical issues that must be solved in the SaaS in smart cities. While blockchain shows promise in solving these issues, the existing blockchain-based data sharing (BBDS) systems are difficult to apply to SaaS in smart cities because of many unresolved issues such as requiring a customized blockchain, huge storage, communication and computation costs, and dependence on a third party to achieve fair trading. We propose a BBDS system model with its security requirements before we present a concrete construction by combining -protocol, Paillier encryption scheme, and any secure symmetrical encryption and signature schemes. To demonstrate the utility of our proposed BBDS system, we present a security analysis and compare our system with other solutions. We implement the prototype in Remix to analyze the gas cost, and we conduct experiments to evaluate the communication and computation costs of the BBDS system using symmetric encryption (advanced encryption standard (AES)) and a signature scheme (elliptic curve digital signature algorithm (ECDSA)).

In the intelligent manufacturing process of solar photovoltaic (PV) cells, the automatic defect detection system using the Industrial Internet of Things (IIoT) smart cameras and sensors cooperated in IIoT has become a promising solution. Many works have been devoted to defect detection of PV cells in a data-driven way. However, because of the subjectivity and fuzziness of human annotation, the data contains a high quantity of noise and unpredictable uncertainties, which creates great difficulties in automatic defect detection. To address this problem, we propose a novel architecture named fuzzy convolution, which integrates fuzzy logic and convolution operations at microscopic level. Combining the proposed fuzzy convolution with the regular convolution, we build a network called Hybrid Fuzzy Convolutional Neural Network (HFCNN). Compared with convolutional neural networks (CNNs), HFCNN can address the uncertainties of PV cell data to improve the accuracy with fewer parameters, making it possible to apply our method in smart cameras. Experimental results on a public dataset show the superiority of our proposed method compared with CNNs.

As quantum computers become more affordable and commonplace, existing security systems that are based on classical cryptographic primitives, such as RSA and Elliptic Curve Cryptography ( ECC ), will no longer be secure. Hence, there has been interest in designing post-quantum cryptographic ( PQC ) schemes, such as those based on lattice-based cryptography ( LBC ). The potential of LBC schemes is evidenced by the number of such schemes passing the selection of NIST PQC Standardization Process Round-3. One such scheme is the Crystals-Dilithium signature scheme, which is based on the hard module-lattice problem. However, there is no efficient implementation of the Crystals-Dilithium signature scheme. Hence, in this article, we present a compact hardware architecture containing elaborate modular multiplication units using the Karatsuba algorithm along with smart generators of address sequence and twiddle factors for NTT, which can complete polynomial addition/multiplication with the parameter setting of Dilithium in a short clock period. Also, we propose a fast software/hardware co-design implementation on Field Programmable Gate Array ( FPGA ) for the Dilithium scheme with a tradeoff between speed and resource utilization. Our co-design implementation outperforms a pure C implementation on a Nios-II processor of the platform Altera DE2-115, in the sense that our implementation is 11.2 and 7.4 times faster for signature and verification, respectively. In addition, we also achieve approximately 51% and 31% speed improvement for signature and verification, in comparison to the pure C implementation on processor ARM Cortex-A9 of ZYNQ-7020 platform.

Clone detection is widely exploited for software vulnerability search. The approaches based on source code analysis cannot be applied to binary clone detection because the same source code can produce significantly different binaries due to different operating systems, microprocessor architectures and compilers. In this paper, we presentBinSeeker, a cross-platform binary seeker that integrates semantic learning and emulation. With the help of the labeled semantic flow graph,BinSeekercan quickly identify$M$candidate functions that are most similar to the vulnerability from the target binary. The value of$M$is relatively large so this semantic learning procedure essentially eliminates those functions that are very unlikely to have the vulnerability. Then, semantic emulation is conducted on these$M$candidates to obtain their dynamic signature sequences. By comparing signature sequences,BinSeekerproduces top-$N$functions that exhibit most similar behavior to that of the vulnerability. With fast filtering of semantic learning and accurate comparison of semantic emulation,BinSeekerseeks vulnerability precisely with little overhead. The experiments on six widely used programs with fifteen known CVE vulnerabilities demonstrate thatBinSeekeroutperforms three state-of-the-art toolsGenius,GeminiandCACompare. Regarding search accuracy,BinSeekerachieves an MRR value of 0.65 in the target programs, whereas the MRR values byGenius,GeminiandCACompareare 0.17, 0.07 and 0.42, respectively. If we consider ranking a function with the targeted vulnerability in the top-5 as accurate,BinSeekerachieves the accuracy of 93.33 percent, while the accuracy of the other three tools is merely 33.33, 13.33 and 53.33 percent, respectively. Such accuracy is achieved with 0.27s on average to determine whether the target binary function contains a known vulnerability, and the time for the other three tools are 1.57s, 0.15s and 0.98s, respectively. Compared to the time used to manually identify the true positive vulnerability from the false positive candidates reported by Gemini, the time overhead ofBinSeekeris negligible. Evidently, the proposedBinSeekerachieves a better balance between accuracy and efficiency.

The development of deep learning techniques has significantly increased the ability of computers to recognize CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart), thus breaking or mitigating the security of existing captcha schemes. To protect against these attacks, recent works have been proposed to leverage adversarial machine learning to perturb captcha pictures. However, they either require the prior knowledge of captcha solving models or lack adaptivity to the evolving behaviors of attackers. Most importantly, none of them has been deployed in practical applications, and their practical applicability and effectiveness are unknown.

Electronic health records (EHR), generated in healthcare, contain extensive digital information, such as diagnoses, medications and complications. Recently, many studies have focused on constructing deep learning (DL) models with EHR data to improve the quality of healthcare services. However, in traditional centralized training, the collection of EHR causes serious privacy issues due to vulnerable transmission channels and untrusted DL service providers. An alternative that can mitigate the above privacy threat is federated learning (FL). It enables multiple healthcare institutions to learn a global predictive model by exchanging locally calculated updates without disclosing the private dataset. Unfortunately, the latest studies have shown that the local updates still expose sensitive information about the original training data. While several privacy-preserving FL protocols have been proposed, few prior works focused on energy consumption issues. Specifically, local training requires extensive computational resources, which is prohibitively expensive for resource-limited institutions. To overcome the above problems, we propose PRCL, a Privacy-aware and Resource-saving Collaborative Learning protocol. To reduce the local computational overhead, we design a novel model splitting method that partitions the neural network into three parts and outsources the computationally large middle part to cloud servers. By using the lightweight data perturbation and packed partially homomorphic encryption, PRCL protects the privacy of the original data and labels, as well as the parameters of the model. Moreover, we analyze the security of the proposed protocol, and demonstrate the superior performance of PRCL in terms of accuracy and efficiency.

LAC, a Ring-LWE based scheme, has shortlisted for the second round evaluation of the National Institute of Standards and Technology Post-Quantum Cryptography (NIST-PQC) Standardization. FPGAs are widely used to design accelerators for cryptographic schemes, especially in resource-constrained scenarios, such as IoT. Sparse Polynomial Multiplication (SPM) is the most compute-intensive routine in LAC. Designing an accelerator for SPM on FPGA can significantly improve the performance of LAC. However, as far as we know, there are currently no works related to the hardware implementation of SPM for LAC. In this paper, the proposed efficient and scalable SPM accelerator fills this gap. More concretely, we firstly develop the Dual-For-Loop-Parallel (DFLP) technique to optimize the accelerator's parallel design. This technique can achieve 2x performance improvement compared with the previous works. Secondly, we design a hardware-friendly modular reduction algorithm for the modulus 251. Our method not only saves hardware resources but also improves performance. Then, we launch a detailed analysis and optimization of the pipeline design, achieving a frequency improvement of up to 34%. Finally, our design is scalable, and we can achieve various performance-area trade-offs through parameter p. Our results demonstrate that the proposed design can achieve a very considerable performance improvement with moderate hardware area costs. For example, our medium-scale architecture for LAC-128 takes only 783 LUTs, 432 FFs, 5BRAMs, and no DSP on an Artix-7 FPGA and can complete LAC's polynomial multiplication in 8512 cycles at a frequency of 202MHz.

Although time-series data collected from users can be utilized to provide services for various applications, they could reveal sensitive information about users. Recently, local differential privacy (LDP) has emerged as the state-of-art approach to protect data privacy by perturbing data locally before outsourcing. However, existing works based on LDP perturb each data point separately without considering the correlations between consecutive data points in time-series. Thus, the important patterns of each time-series might be distorted by existing LDP-based approaches, leading to severe degradation of data utility. In this paper, we focus on real-time data collection under a honest-but-curious server, and propose a novel pattern-aware privacy-preserving approach, called PatternLDP, to protect data privacy while the pattern of time-series can still be preserved. To this end, instead of providing the same level of privacy protection at each data point, each user only samples remarkable points in time-series and adaptively perturbs them according to their impacts on local patterns. In particular, we propose a pattern-aware sampling method based on Piecewise Linear Approximation (PLA) to determine whether to sample and perturb current data point. To reduce the utility loss caused by pattern change after perturbation, we propose an importance-aware randomization mechanism to adaptively perturb sampled data locally while achieving better trade-off between privacy and utility. A novel metric-based w-event privacy is introduced to measure the privacy protection degree for pattern-rich time-series. We prove that PatternLDP can provide the above privacy guarantee, and extensive experiments on real-world datasets demonstrate that PatternLDP outperforms existing mechanisms and can effectively preserve the important patterns.

Coverage-guided fuzzing is one of the most popular software testing techniques for vulnerability detection. While effective, current fuzzing methods suffer from significant performance penalty due to instrumentation overhead, which limits its practical use. Existing solutions improve the fuzzing speed by decreasing instrumentation overheads but sacrificing coverage accuracy, which results in unstable performance of vulnerability detection.

Today's smart devices like fitness tracker, smartwatch, etc., often employ Bluetooth Low Energy (BLE) for data transmission. Such devices thus become our information portal, e.g., SMS message and notifications are delivered to those devices through BLE. In this study, we present BlueDoor, which can obtain unauthorized information from smart devices via BLE vulnerability. We thoroughly examine the BLE protocol, and leverage its intrinsic properties designed for low-cost embedded and wearable devices to bypass the encryption and authentication in BLE. By mimicking a low capacity device to downgrade the process of encryption key negotiation and authentication, BlueDoor can enforce a new key with the peripheral BLE device and pass the authentication without user participation. As a result, BlueDoor can extract BLE packets as well as read/write stored data on BLE devices. We show that BlueDoor works well on the fundamental design tradeoff of using BLE on diverse embedded and wearable devices, and thus can be generalized to various BLE devices. We implement the BlueDoor design and examine its performance on 15 COTS BLE enabled smart devices, including fitness trackers, smartwatch, smart bulb, etc. The results show that BlueDoor can break the information flow and obtain different types of information (e.g., SMS message, notifications) delivered to BLE devices. In addition to privacy threats, this further means traditional operations such as using SMS for verification in widely adopted authentication, are insecure.

The identity‐based signature (IBS) scheme is one of the most promising secure and widely used cryptographic primitives for electronic commerce applications. For example, ID‐based signing in a multi‐party setting, without ever revealing any private and secret information , has received considerable interest in distributed applications such as a global manufacturer. However, there is no practical solution for such a group setting (e.g. more than two parties). Therefore, in this study, the authors present the first distributed identity‐based signing protocol for the global electronic commerce system. Specifically, the authors’ designed protocol allows a group of parties to generate the signature in a decentralised and fair manner. They also prove that their proposed protocol is secure against a malicious adversary under the discrete logarithm and decisional Diffie–Hellman assumptions. Moreover, they implement the protocol using the MIRACL libraries on physical computing devices. Findings from the evaluations demonstrate the practical utility of their proposed protocol, in terms of achieving high level of security within a reasonable time framework (e.g. signing time (including communication latency and waiting delay) takes 311.86 ms for three parties, 558.2 ms for five parties, and 707.21 ms for seven parties, under a single‐thread implementation).

With the high popularity of IoT devices, industrial IoT platforms, such as smart factories and oilfield industrial control systems, have become a new trend in the development of smart city. Although various manufacturers pay wide attention to the different functional requirements of IoT platforms, they seldom consider security issues, especially in terms of data security, which has led to a large number of cases of privacy leakage. Some works have been made to provide secure and reliable communication solutions for industrial IoT platforms, unfortunately, as different communication protocols and interaction models are adopted in different scenarios, these solutions are mainly isolated and fragmented. Therefore, it is an urgent challenge to construct a universal cross-platform secure communication scheme for industrial IoT platforms. In this article, we analyze the logic and requirements of different industrial IoT scenarios to abstracts them into a universal model. We summarize the possible attacks on different industrial IoT platforms and design a security scheme to capture these attacks based on the conditional proxy re-encryption primitive. The proposed scheme ensures that data cannot be accessed by an unauthorized user. We also evaluate the security and performance of our scheme, and the experimental results show that our scheme can achieve the functionality and security requirements with low overhead.

As a promising data-driven technology, deep learning has been widely employed in a variety of Internet-of-Things (IoT) applications. Examples include automated navigation, telemedicine, and smart home. To protect the data privacy of deep-learning-based IoT applications, a few privacy-preserving approaches have also been exploited, designed, and implemented in various scenarios. However, state-of-the-art works are still defective in accuracy, efficiency, and functionality. In this article, we propose the privacy-aware and asynchronous deep-learning-assisted IoT applications (PADL), a privacy-aware and asynchronous deep learning framework that enables multiple data collecting sites to collaboratively train deep neural networks (DNNs), while keeping the confidentiality of private data to each other. Specifically, we first design a layerwise importance propagation (LIP) algorithm to quantify the importance of the model's weights held by each site. Then, we present the customized perturbation mechanism, a precise combination of the LIP algorithm and differential privacy mechanism, which helps to make optimal tradeoffs between the availability and privacy of local models. Furthermore, to fully use the computing resources of all sites, for the first time, we propose an advanced asynchronous optimization (AAO) protocol to perform global updates without waiting. Theoretical analysis shows that the PADL is robust to extreme collusion even with only one reliable site while supporting lock-free optimization. Finally, extensive experiments conducted on real-world data sets using TensorFlow library show that the PADL outperforms the existing systems in terms of efficiency and prediction accuracy.

Data provenance is an effective method to evaluate data reliability and has become a research hotspot in recent years. However, the size of the data provenance will increase rapidly as the number of hops experienced increases, which conflicts with the limitations of energy, storage, and resources of IoT devices. The existing DP provenance compression algorithm has a high error rate when decompressing. To solve this problem, we propose an index-based provenance compression algorithm, which adopts the idea of common substring matching, combined with path identifier and path index to represent the path information in the data provenance, thereby achieving the purpose of reducing the size of data provenance. In addition, we extend the data provenance scheme to attack detection and propose a malicious node identification method based on data provenance. The simulation results show that the proposed scheme has a high compression ratio and higher decoding accuracy and has high accuracy in malicious node identification.

The implementations of post-quantum cryptographic algorithms have been newly explored, whereas, the protection against side-channel attacks shall be considered upfront, since it can have a non-negligible impact on security and performance. In this article, the security of supersingular isogeny key encapsulation (SIKE), a second-round candidate of NIST's on-going post-quantum standardization process, is thoroughly evaluated under side-channel analysis. First, the vulnerabilities of reference and optimized implementations of SIKE are thoroughly analyzed in terms of both horizontal and vertical side-channel leakage. After the optimized SIKE, which is based on Three-point Montgomery Differential Ladder algorithm, is proved to be constant-time and there is no horizontal leakage, a vertical vulnerability is analyzed based on the source code at the algorithmic level, and a theoretical differential power analysis (DPA) attack is proposed. In order to exploit this vulnerability, the differential electromagnetic attack (DEMA) is put into practice to extract the private key of SIKE based on a 32-bit ARM platform. To the best of our knowledge, this is the first practical side-channel attack at SIKE implemented on real ARM-based devices. Our experiments show that the DEMA needs only hundreds of electromagnetic traces to carry out the attack. More importantly, an efficient window-based countermeasure is proposed to eliminate the vertical leakage and prevent side-channel attacks with only a little overhead. The security of our countermeasure is carefully evaluated against most of well-known power analysis attacks. Through careful evaluation and comparison with other countermeasures, this method can lead to higher security at a very small cost in terms of time and memory.

Embedded processors have been widely used for building up Internet of Things (IoT) platforms, in which the security issue is becoming critical. This paper studies efficient techniques of lattice-based cryptography on these processors and presents the first implementation of ring-LWE encryption on ARM NEON and MSP430 architectures. For ARM NEON architecture, we propose a vectorized version of Iterative Number Theoretic Transform (NTT) for high-speed computation of polynomial multiplication on ARM NEON platforms and a 32-bit variant of SAMS2 technique for fast reduction. For MSP430 architecture, we propose an optimized SWAMS2 reduction technique, which consists of five different basic operations, including Shifting, Swapping, Addition, and two Multiplication-Subtractions. Regarding of the sampling from the discrete Gaussian distribution, we adopt Knuth-Yao sampler, accompanied with optimized methods such as Look-Up Table (LUT) and byte-scanning. Subsequently, a full-fledged implementation of Ring-LWE is presented by both taking advantage of our proposed method and previous optimization techniques re-designed for desired platforms. Our ring-LWE implementation of encryption/decryption at a classical security level of 128 bits requires only 149:4k=32:8k clock cycles on ARM NEON, and 2126:3k=244:5k clock cycles on MSP430. These results are roughly 7 times faster than the fastest ECC implementation on desired platforms with same security level.

Embedded systems are increasingly interconnected in the emerging application scenarios. Many of these applications are safety critical, making it a high priority to ensure that the systems are free from malicious attacks. This work aims to detect vulnerabilities, that could be exploited by adversaries to compromise functional correctness, in the embedded firmware, which is challenging especially due to the absence of source code. In particular, we propose EM-Fuzz, a firmware vulnerability detection technique that tightly integrates fuzzing with real-time memory checking. Based on the memory instrumentation, the firmware fuzzing can not only be guided by the traditional branch coverage to generate high-quality seeds to explore hard-to-reach regions but also by the recorded memory sensitive operations to continuously exercise sensitive regions which are prone to being attacked. More importantly, the instrumentation integrates real-time memory checkers to expose memory vulnerabilities, which is not well-supported by existing fuzzers without source code. The experiments on several real-world embedded firmware such as OpenSSL demonstrate that EM-Fuzz significantly improves the performance of state-of-the-art fuzzing tools, such as AFL and AFLFast, with the coverage improvements of 93.98% and 46.89%, respectively. Furthermore, EM-Fuzz exposes a total of 23 vulnerabilities, with an average of about 7-h per vulnerability. AFL and AFLFast together find 10 vulnerabilities, costing about 13 h and 10-h per vulnerability on average, respectively. Out of these 23 vulnerabilities, 16 are previously unknown and have been reported to the upstream product vendors, 7 of which have been assigned with unique CVE identifiers in the U.S. National Vulnerability Database.

This work deals with the energy-efficient, high-speed and high-security implementation of elliptic curve scalar multiplication, elliptic curve Diffie-Hellman (ECDH) key exchange and elliptic curve digital signatures on embedded devices using FourQ and incorporating strong countermeasures to thwart a wide variety of side-channel attacks. First, we set new speed records for constant-time curve-based scalar multiplication, DH key exchange and digital signatures at the 128-bit security level with implementations targeting 8, 16 and 32-bit microcontrollers. For example, our software computes a static ECDH shared secret in ~6.9 million cycles (or 0.86 seconds @8 MHz) on a low-power 8-bit AVR microcontroller which, compared to the fastest Curve25519 and genus-2 Kummer implementations on the same platform, offers 2× and 1.4× speedups, respectively. Similarly, it computes the same operation in ~495 thousand cycles on a 32-bit ARM Cortex-M4 microcontroller, achieving a factor-1.9 speedup when compared to the fastest Curve25519 implementation targeting another Cortex-M4 platform. A similar speed performance is observed in the case of digital signatures. Second, we engineer a set of side-channel countermeasures taking advantage of FourQ's rich arithmetic and propose a secure implementation that offers protection against a wide range of sophisticated side-channel attacks, including differential power analysis (DPA). Despite the use of strong countermeasures, the experimental results show that our FourQ software is still efficient enough to outperform implementations of Curve25519 that only protect against timing attacks. Finally, we perform a differential power analysis evaluation of our software running on an ARM Cortex-M4, and report that no leakage was detected with up to 10 million traces. These results demonstrate the potential of deploying FourQ on low-power applications such as protocols forthe Internet of Things.

Natural language processing (NLP) allows a computer program to understand human language as it is spoken, and has been increasingly deployed in a growing number of applications, such as machine translation, sentiment analysis, and electronic voice assistant. While information obtained from different sources can enhance the accuracy of NLP models, there are also privacy implications in the collection of such massive data. Thus, in this paper, we design a privacy-preserving system SecureNLP, focusing on the instance of recurrent neural network (RNN)based sequence-to-sequence with attention model for neural machine translation. Specifically, for non-linear functions such as sigmoid and tanh, we design two efficient distributed protocols using secure multi-party computation (MPC), which are used to carry out the respective tasks in the SecureNLP. We also prove the security of these two protocols (i.e., privacy-preserving long short-term memory network PrivLSTM, and privacy-preserving sequence to sequence transformation PrivSEQ2SEQ) in the semi-honest adversary model, in the sense that any honest-butcurious adversary cannot learn anything else from the messages they receive from other parties. The proposed system is implemented in C++ and Python, and the findings from the evaluation demonstrate the utility of the protocols in cross-domain NLP.

Mining pools have become dominant in today's bitcoin mining network, where miners can pool their powers together for reduced variance of block mining and steadier stream of potential income. Along with the continuous evolvement of mining pools are the increasingly intense competitions among them. Recent empirical studies have shown that the distributed denial-of-service (DDoS) attack is one of the most common ways for competing mining pools to sabotage the rivals and earn illegitimate rewards. Existing efforts have been made on using static game models to analyze the interactions between mining pools, and derive the Nash Equilibrium and optimal attacking strategies in a one-time static context. To better understand the impact of such DDoS attacks, in this paper, we take a starkly different approach, and for the first time address the dynamics in mining pool attacks. Specifically, we start by formulating the interactive competition among mining pools as a general-sum stochastic game. Then we propose an efficient Nash learning algorithm to obtain the near optimal attacking strategy that maximizes the expected long-term utility. Our theoretical analysis and extensive experimental results both show that the proposed strategy outperforms the baseline myopic learning algorithm, which only aims at maximizing the revenue in the current time stage. These findings, together with our proposed stochastic game model and learning algorithm, are expected to provide more practical guidelines for mining pools to survive and thrive in the highly-competitive bitcoin ecosystem.

Internet of Things (IoT) devices, such as intelligent road side units and video-based detectors, are being deployed in emerging applications like sustainable and intelligent transportation systems. The primary obstacles against the development of these IoT devices are various security threats and huge energy consumption. In this article, we study the problem of scheduling tasks onto a heterogeneous multiprocessor system on a chip (MPSoC) deployed in IoT for optimizing quality of security under energy, real-time, and task precedence constraints. We first provide a mixed-integer linear programming (MILP) formulation for allocating and scheduling dependent tasks with energy and real-time constraints on a heterogeneous MPSoC system to maximize system quality of security. In order to efficiently solve the formulated MILP, we then propose an analysis-based two-stage scheme that determines the allocation, operating frequency, and security service of tasks to maximize system quality of security while satisfying the design constraints. We finally carry out extensive simulation experiments to validate our proposed two-stage scheme and MILP approach. Simulation results demonstrate that the proposed two-stage scheme outperforms a number of representative existing approaches in saving energy and improving system quality of security. The results also show that the proposed MILP approach can achieve the best performance and the proposed two-stage scheme has a close performance to the MILP approach.

Fuzzing is widely used for vulnerability detection. One of the challenges for an efficient fuzzing is covering code guarded by constraints such as the magic number and nested conditions. Recently, academia has partially addressed the challenge via whitebox methods. However, high-level constraints such as array sorts, virtual function invocations, and tree set queries are yet to be handled. To meet this end, we present VisFuzz, an interactive tool for better understanding and intervening fuzzing process via real-time visualization. It extracts call graph and control flow graph from source code, maps each function and basic block to the line of source code and tracks real-time execution statistics with detail constraint contexts. With VisFuzz, test engineers first locate blocking constraints and then learn its semantic context, which helps to craft targeted inputs or update test drivers. Preliminary evaluations are conducted on four real-world programs in Google fuzzer-test-suite. Given additional 15 minutes to understand and intervene the state of fuzzing, the intervened fuzzing outperform the original pure AFL fuzzing, and the path coverage improvements range from 10.84% to 150.58%, equally fuzzed by for 12 hours.

Summary To protect assets and resources from being hacked, intrusion detection systems are widely implemented in organizations around the world. However, false alarms are one challenging issue for such systems, which would significantly degrade the effectiveness of detection and greatly increase the burden of analysis. To solve this problem, building an intelligent false alarm filter using machine learning classifiers is considered as one promising solution, where an appropriate algorithm can be selected in an adaptive way in order to maintain the filtration accuracy. By means of cloud computing, the task of adaptive algorithm selection can be offloaded to the cloud, whereas it could cause communication delay and increase additional burden. In this work, motivated by the advent of edge computing, we propose a framework to improve the intelligent false alarm reduction for DIDS based on edge computing devices. Our framework can provide energy efficiency as the data can be processed at the edge for shorter response time. The evaluation results demonstrate that our framework can help reduce the workload for the central server and the delay as compared to the similar studies.

In vehicle-to-grid (V2G) networks, battery-powered vehicle (BV) provides service to the power grid. In order to encourage more BVs to provide the service for power grid, it is necessary to reward the BVs from the power grid. To extensively deploy V2G networks, some security and privacy problems must be solved. In this paper, for the first time, we propose the novel concept of blockchain-based anonymous rewarding scheme (BBARS) for V2G networks. The novel concept comes from the application requirement which has not been solved by now. We give the formal system model and security model of BBARS. Then, we design the concrete BBARS scheme by making use of two different public key cryptosystem. Through security analysis and performance analysis, the designed scheme is provably secure and efficient. The analysis results also show the designed BBARS scheme is practical for secure V2G networks in smart grid.

Image hashing schemes have been widely used in content authentication, image retrieval, and digital forensic. In this paper, a novel image hashing algorithm (SSL) by incorporating the most stable keypoints and local region features is proposed, which is robust against various content-preserving manipulations, even multiple combinatorial manipulations. The proposed algorithm combines S_ cale invariant feature transform (SIFT) with S_ aliency detection to extract the most stable keypoints. Then, the L_ ocal binary pattern (LBP) feature extraction method is exploited to generate local region features based on these keypoints. After that, the information of keypoints and local region features are merged into a hash vector. Finally, a secret key is used to randomize the hash vector, which can prevent attackers from forging the image and the hash value. Experimental results demonstrate that the proposed hashing algorithm can identify visually similar images which are under both single and combinatorial content-preserving manipulations, even multiple combinations of manipulations. It can also identify maliciously forged images which are under various content-changing manipulations. The collision probability between hashes of different images is nearly zero. Besides, the evaluation of key-dependent security shows that the proposed scheme is secure that an attacker cannot forge or estimate the correct hash value without the knowledge of the secret key.

Recent progress in quantum physics shows that quantum computers may be a reality in the not too distant future. Post-quantum cryptography (PQC) refers to cryptographic schemes that are based on hard problems which are believed to be resistant to attacks from quantum computers. The supersingular isogeny Diffie-Hellman (SIDH) key exchange protocol shows promising security properties among various post-quantum cryptosystems that have been proposed. In this paper, we propose two efficient modular multiplication algorithms with special primes that can be used in SIDH key exchange protocol. Hardware architectures for the two proposed algorithms are also proposed. The hardware implementations are provided and compared with the original modular multiplication algorithm. The results show that the proposed finite field multiplier is over 6.79 times faster than the original multiplier in hardware. Moreover, the SIDH hardware/software codesign implementation using the proposed FFM2 hardware is over 31 percent faster than the best SIDH software implementation.

In this paper, we present memory-efficient and scalable implementations of NIST standardized elliptic curves P-256, P-384 and P-521 on three ARMv6-M processors (i.e. Cortex-M0, M0+, and M1). Specifically, we propose a refined approach to perform the Multiply-ACcumulate (MAC) operation using hardware multiplier provided by ARMv6-M processor, and a compact doubling routine for multi-precision squaring that executes both doubling and partial product operations in an efficient way. We demonstrate that the proposed squaring implementation achieves a speed up of 28 percent compared to the same operation employed in Micro-ECC. Then, we reduce one modular reduction in co-Z conjugate point addition by using lazy reduction and special form representation (CD-AB, EF-AB), which further reduces the execution time of both P-256 and P-384 implementations. Finally, we propose scalable implementations of ECC scalar multiplication on ARMv6-M processors that are widely used for Internet of Things applications.

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In 2015, NIST held a workshop calling for new candidates for the next generation of elliptic curves to replace the almost two-decade old NIST curves. Nothing Upon My Sleeves (NUMS) curves are among the potential candidates presented in the workshop. Here, we present the first implementation of the NUMS256, NUMS379, and NUMS384 curves on two types of embedded devices. The implementations, which exhibit regular, constant-time execution to protect against timing and simple side-channel attacks, set new speed records and advance the state-of-the-art of curve-based (without endomorphism) scalar multiplication on 8-bit AVR and 32-bit ARM11 microcontrollers. For example, our NUMS256 implementation computes a scalar multiplication in ~1.4 million cycles on a low-power 32-bit ARM11 microcontroller using mixed C and assembly language. These results demonstrate the potential of deploying IoT-NUMS on constrained and low-power applications such as protocols for the Internet of Things.

Security surveillance is critical to social harmony and people's peaceful life. It has a great impact on strengthening social stability and life safeguarding. Detecting anomaly timely, effectively and efficiently in video surveillance remains challenging. This paper proposes a new approach, called S2-VAE, for anomaly detection from video data. The S2-VAE consists of two proposed neural networks: a Stacked Fully Connected Variational AutoEncoder (SF-VAE) and a Skip Convolutional VAE (SC-VAE). The SF-VAE is a shallow generative network to obtain a model like Gaussian mixture to fit the distribution of the actual data. The SC-VAE, as a key component of S2-VAE, is a deep generative network to take advantages of CNN, VAE and skip connections. Both SF-VAE and SC-VAE are efficient and effective generative networks and they can achieve better performance for detecting both local abnormal events and global abnormal events. The proposed S2-VAE is evaluated using four public datasets. The experimental results show that the S2-VAE outperforms the state-of-the-art algorithms. The code is available publicly at https://github.com/tianwangbuaa/.

Recent progress on quantum physics shows that quantum computers may be a reality in the not too distant future. Based on new mathematical hard problems, post-quantum cryptography (PQC) has been studied to make sure the attacks from quantum computers can be resistant. The latest supersingular isogeny Diffie-Hellman (SIDH) key exchange protocol shows promising security properties among various post-quantum cryptosystems. In this paper, we propose an improved modular multiplication algorithm with special primes that can be used in SIDH key exchange protocol. Both software and hardware implementations are provided and compared with original modular multiplication algorithm. The results show that the software results of improved algorithm can be 24% faster than the original software implementation, while the hardware implementation based on the proposed hardware architecture can be 6 times faster than previous hardware implementation.

The papers in this special section examine the impact of cryptographic engineering in a post-quantum world. The vast majority of public-key cryptosystems currently in use is based on integer factorization and (elliptic curve) discrete logarithm problems, which are believed to be intractable with current computing technology. However, these hard problems can be solved in polynomial time by using Shor’s algorithm (or one of its variants) on a quantum computer. Recent progress towards the development of a largescale, fault-tolerant quantum computer has motivated the interest for post-quantum cryptography (a.k.a. quantum-safe or quantum-resistant cryptography) by governments, enterprises and the cryptography community.

Recently, Rahulamathavan et al. propose a privacy preserving scheme for outsourcing SVM classification. Their core contribution is a secure protocol to attain the sign of numbers in encrypted form. In this paper, we observe that Rahulamathavan et al.'s protocol will suffer from some soundness and security problems. Then, we propose a new scheme to securely obtain the encrypted numbers' sign. Theoretical analysis and experiment results show our proposed scheme can not only fix the soundness and security problems, but also achieve higher efficiency.

Multiplication of large integers is a fundamental operation for public key cryptography. In contemporary public key cryptography, the sizes of integers are typically from more than one hundred bits to even several thousands of bits. Because these sizes exceed the bit widths of all general-purpose processors, these multiplications must be performed with a multiprecision multiplication algorithm which splits the operation into multiple partial products and accumulation steps. To ensure efficiency, multiprecision multiplication algorithms must be designed with special care and optimized for the instruction sets of specific processors. Consequently, developing efficient multiprecision multiplication algorithms and optimizing them for specific platforms has been an active research topic. In this paper, we optimize multiprecision multiplication and squaring specifically for the 64-bit ARMv8 processors which are widely used, for example, in modern smart phones and tablets. We combine the subtractive Karatsuba algorithm, operand-scanning techniques (for multiplication) and sliding-block-doubling methods (for squaring) to accelerate the performance of the 256-bit multiprecision multiplication and squaring by 7.6% and 7.0% compared to the OpenSSL implementations. We focus particularly on the multiprecision multiplications that are required in elliptic curve cryptography. Our implementation supports general elliptic curves of various sizes and all source codes are available in public domain.

With the prevalence of smartphones, app markets such as Apple App Store and Google Play has become the center stage in the mobile app ecosystem, with millions of apps developed by tens of thousands of app developers in each major market. This paper presents a study of the mobile app ecosystem from the perspective of app developers. Based on over one million Android apps and 320,000 developers from Google Play, we analyzed the Android app ecosystem from different aspects. Our analysis shows that while over half of the developers have released only one app in the market, many of them have released hundreds of apps. We classified developers into different groups based on the number of apps they have released, and compared their characteristics. Specially, we have analyzed the group of aggressive developers who have released more than 50 apps, trying to understand how and why they create so many apps. We also investigated the privacy behaviors of app developers, showing that some developers have a habit of producing apps with low privacy ratings. Our study shows that understanding the behavior of mobile developers can be helpful to not only other app developers, but also to app markets and mobile users.

Verification of an ECDSA signature requires a double scalar multiplication on an elliptic curve. In this work, we study the computation of this operation on a twisted Edwards curve with an efficiently computable endomorphism, which allows reducing the number of point doublings by approximately 50 percent compared to a conventional implementation. In particular, we focus on a curve defined over the 207-bit prime field Fpwith p = 2207- 5,131. We develop several optimizations to the operation and we describe two hardware architectures for computing the operation. The first architecture is a small processor implemented in 0.13 μm CMOS ASIC and is useful in resource-constrained devices for the Internet of Things (IoT) applications. The second architecture is designed for fast signature verifications by using FPGA acceleration and can be used in the server-side of these applications. Our designs offer various trade-offs and optimizations between performance and resource requirements and they are valuable for IoT applications.

In today's world of the internet, billions of computer systems are connected to one another in a global network. The internet provides an unsecured channel in which hundreds of terabytes of data is being transmitted daily. Computer and software systems rely on encryption algorithms such as block ciphers to ensure that sensitive data remains confidential and secure. However, adversaries can leverage the statistical behavior of underlying ciphers to recover encryption keys. Accurate evaluation of the security margins of these encryption algorithms remains to be a big challenge. In this paper, we tackle this issue by introducing several searching strategies based on differential cryptanalysis. By clustering differential paths, the searching algorithm derives more accurate distinguishers as compared to examining individual paths, which in turn provides a more accurate estimation of cipher security margins. We verify the effectiveness of this technique on ciphers with the generalized Feistel and SPN structures, whereby the best distinguishers for each of the investigated ciphers were obtained by discovering clusters with thousands of paths. With the KATAN block cipher family as a test case, we also show how to apply the searching algorithm alongside other cryptanalysis techniques such as the boomerang attack and related-key model to obtain the best cryptanalytic results. This also depicts the flexibility of the proposed searching scheme, which can be tailored to improve upon other differential attack variants. In short, the proposed searching strategy realizes an automated security evaluation tool with higher accuracy compared to previous techniques. In addition, it is applicable to a wide range of encryption schemes which makes it a flexible tool for both academic research and industrial purposes.

Lightweight Elliptic Curve Cryptography (ECC) is a critical component for constructing the security system of Internet of Things (IoT). In this paper, we define an emerging family of lightweight elliptic curves to meet the requirements on some resource-constrained devices. We present the design of a scalable, regular, and highly-optimized ECC library for both MICAz and Tmote Sky nodes, which supports both widely-used key exchange and signature schemes. Our parameterized implementation of elliptic curve group arithmetic supports pseudo-Mersenne prime fields at different security levels with two optimized-specific designs: the high-speed version (HS) and the memory-efficient (ME) version. The former design achieves record times for computation of cryptographic schemes at roughly$80\sim 128$-bit security levels, while the latter implementation only requires half of the code size of the current best implementation. We also describe our efforts to evaluate the energy consumption and harden our library against some basic side-channel attacks, e.g., timing attacks and simple power analysis (SPA) attacks.

Many resource-constrained embedded devices, such as wireless sensor nodes, require public key encryption or a digital signature, which has induced plenty of research on efficient and secure implementation of elliptic curve cryptography (ECC) on 8-bit processors. In this work, we study the suitability of a special class of finite fields, called optimal prime fields (OPFs), for a “lightweight” ECC implementation with a view toward high performance and security. First, we introduce a highly optimized arithmetic library for OPFs that includes two implementations for each finite field arithmetic operation, namely a performance-optimized version and a security-optimized variant. The latter is resistant against simple power analysis attacks in the sense that it always executes the same sequence of instructions, independent of the operands. Based on this OPF library, we then describe a performance-optimized and a security-optimized implementation of scalar multiplication on the elliptic curve over OPFs at several security levels. The former uses the Gallant-Lambert-Vanstone method on twisted Edwards curves and reaches an execution time of 3.14M cycles (over a 160-bit OPF) on an 8-bit ATmega128 processor, whereas the latter is based on a Montgomery curve and executes in 5.53M cycles.

In 2014, a new fault analysis called blind fault attack (BFA) was proposed, in which attackers can only obtain the number of different faulty outputs without knowing the public data. The original BFA requires 480,000 fault injections to recover a 128-bit AES key. This work attempts to reduce the number of fault injections under the same attack assumptions. We analyze BFA from an information theoretical perspective and introduce a new probability-based distinguisher. Three approaches are proposed for different attack scenarios. The best one realized a 66.8% reduction of the number of fault injections on AES.

Over recent years lattice-based cryptography has received much attention due to versatile average-case problems like Ring-LWE or Ring-SIS that appear to be intractable by quantum computers. In this work, we evaluate and compare implementations of Ring-LWE encryption and the bimodal lattice signature scheme (BLISS) on an 8-bit Atmel ATxmega128 microcontroller. Our implementation of Ring-LWE encryption provides comprehensive protection against timing side-channels and takes 24.9ms for encryption and 6.7ms for decryption. To compute a BLISS signature, our software takes 317ms and 86ms for verification. These results underline the feasibility of lattice-based cryptography on constrained devices.

There exist some inappropriate citations and typos in our paper ‘Social Rational Secure Multi-party Computation’, Vol. 26, No. 5 (2014), Pages: 1067–1083. We would like to use this corrigendum to point out these places so that the readers can understand the context of this paper in a better way. We are sorry for the unexpected inconvenience we brought for ‘Concurrency and Computation: Practice and Experience’ and the authors of the reference [27] cited in our paper, as well as the readers of our paper. The following corrections should be included.

Abstract Advanced modern processors support single instruction, multiple data instructions (e.g., Intel‐AVX and ARM‐NEON) and a massive body of research on vector‐parallel implementations of modular arithmetic, which are crucial components for modern public‐key cryptography ranging from Rivest, Shamir, and Adleman (RSA), ElGamal, Digital Signature Algorithm (DSA), and elliptic curve cryptography, have been conducted. In this paper, we introduce a novel double operand scanning method to speed up multi‐precision squaring with non‐redundant representations on single instruction, multiple data architecture where the part of the operands are doubled to compute the squaring operation without read‐after‐write dependencies between source and destination variables. Afterwards, Karatsuba algorithm is applied to both multiplication and squaring operations. For modular multiplication, separated Montgomery algorithm is chosen. Finally, the Rivest, Shamir, and Adleman (RSA) implementations outperform the best‐known results on the ARM‐NEON platforms. Copyright © 2017 John Wiley & Sons, Ltd.

Abstract In this paper, we show efficient implementations of binary field multiplication over ARMv8. We exploit an advanced 64‐bit polynomial multiplication (PMULL) supported by ARMv8 and conduct multiple levels of asymptotically faster Karatsuba multiplication for polynomial multiplication. Finally, our method completed binary field multiplication within 57 and 153 clock cycles for B‐251 and B‐571 cases, respectively. Proposed method improves the speed‐performance by a factor of 4.5 times than previous techniques on same target platform. Copyright © 2016 John Wiley & Sons, Ltd.

In this article, we present a hybrid method to improve the performance of the Montgomery reduction by taking advantage of the Karatsuba technique. We divide the Montgomery reduction into two sub-parts, including one for the conventional Montgomery reduction and the other one for Karatsuba-aided multiplication. This approach reduces the multiplication complexity of n -limb Montgomery reduction from θ( n 2 + n ) to asymptotic complexity θ (7 n 2 /8 + n ). Our practical implementation results over an 8-bit microcontroller also show performance enhancements by 11%.

In this paper, we introduce a highly optimized software implementation of standards-compliant elliptic curve cryptography (ECC) for wireless sensor nodes equipped with an 8-bit AVR microcontroller. We exploit the state-of-the-art optimizations and propose novel techniques to further push the performance envelope of a scalar multiplication on the NIST P-192 curve. To illustrate the performance of our ECC software, we develope the prototype implementations of different cryptographic schemes for securing communication in a wireless sensor network, including elliptic curve Diffie–Hellman (ECDH) key exchange, the elliptic curve digital signature algorithm (ECDSA), and the elliptic curve Menezes–Qu–Vanstone (ECMQV) protocol. We obtain record-setting execution times for fixed-base, point variable-base, and double-base scalar multiplication. Compared with the related work, our ECDH key exchange achieves a performance gain of roughly 27% over the best previously published result using the NIST P-192 curve on the same platform, while our ECDSA performs twice as fast as the ECDSA implementation of the well-known TinyECC library. We also evaluate the impact of Karatsuba’s multiplication technique on the overall execution time of a scalar multiplication. In addition to offering high performance, our implementation of scalar multiplication has a highly regular execution profile, which helps to protect against certain side-channel attacks. Our results show that NIST-compliant ECC can be implemented efficiently enough to be suitable for resource-constrained sensor nodes.

Public-Key Cryptography (PKC) is an indispensable building block of modern security protocols, and, thus, essential for secure communication over insecure networks. Despite a significant body of research devoted to making PKC more "lightweight," it is still commonly perceived that software implementations of PKC are computationally too expensive for practical use in ultra-low power devices such as wireless sensor nodes. In the present paper we aim to challenge this perception and present a highly-optimized implementation of Elliptic Curve Cryptography (ECC) for the TI MSP430 series of 16-bit microcontrollers. Our software is inspired by MoTE-ECC and supports scalar multiplication on two families of elliptic curves, namely Montgomery and twisted Edwards curves. However, in contrast to MoTE-ECC, we use pseudo-Mersenne prime fields as underlying algebraic structure to facilitate inter-operability with existing ECC implementations. We introduce a novel "zig-zag" technique for multiple-precision squaring on the MSP430 and assess its execution time. Similar to MoTE-ECC, we employ the Montgomery model for variable-base scalar multiplications and the twisted Edwards model if the base point is fixed (e.g. to generate an ephemeral key pair). Our experiments show that the two scalar multiplications needed to perform an ephemeral ECDH key exchange can be accomplished in 4.88 million clock cycles altogether (using a 159-bit prime field), which sets a new speed record for ephemeral ECDH on a 16-bit processor. We also describe the curve generation process and analyze the execution time of various field and point arithmetic operations on curves over a 159-bit and a 191-bit pseudo-Mersenne prime field.

Abstract Wireless sensor networks (WSNs) pose a number of unique security challenges that demand innovation in several areas including the design of cryptographic primitives and protocols. Despite recent progress, the efficient implementation of Elliptic Curve Cryptography (ECC) for WSNs is still a very active research topic, and techniques to further reduce the time and energy cost of ECC are eagerly sought. This paper presents an optimized ECC implementation that we developed from scratch to comply with the severe resource constraints of 8‐bit sensor nodes such as the MICAz and IRIS motes. Our ECC software uses Optimal Prime Fields as underlying algebraic structure and supports two different families of elliptic curves, namely, Weierstraß‐form and twisted Edwards‐form curves. Due to the combination of efficient field arithmetic and fast group operations, we achieve an execution time of 5.3·106clock cycles for a full 160‐bit scalar multiplication on an 8‐bit ATmega128 microcontroller, which is more than three times faster than the widely used TinyECC library. Our implementation also shows that the energy cost of scalar multiplication on a MICAz (or IRIS) mote amounts to just 17.34mJ when using a twisted Edwards curve over a 160‐bit Optimal Prime Field. This result further demonstrates the advantage of special family of elliptic curves for resource‐constrained environments. Copyright © 2015 John Wiley & Sons, Ltd.

Efficient implementation of elliptic curve cryptography on resource-constrained microcontroller is considered to be one of the hot and challenging research topics because of the limited computing power and storages of target platforms and high computational costs of elliptic curve cryptography. In this paper, we focus on enhancing the performance of scalar multiplication over GF2m by suggesting a new technique for speeding up the performance of multiplication, called Karatsuba-Block-Comb KBC multiplication. KBC method combines both the advantages of Karatsuba algorithm and Block-Comb method. This technique replaces the part of expensive Block-Comb binary field multiplications with several cheap additions by following Karatsuba rule. In case of squaring, we describe an optimized squaring algorithm with 8-bit look-up table that is significantly faster than previous works with 4-bit look-up table. Both of the proposed approaches improve the best known results by a factor of 24.6% and 16.8% 160-bit operand over 8-bit AVR processor Atmel Corporation, San Jose, CA, USA, respectively. Finally, we realize the scalar multiplication over GF2163, which only requires 0.29s for a full scalar multiplication when the processor runs at 7.37MHz. This result outperforms the previous best implementation by a factor of 9.3%. The research results presented in this paper prove that it is also possible to achieve high performance over binary fields by combing the algorithm with sub-quadratic complexity. Furthermore, we suggest constant time KBC method. Block-Comb method does not provide constant time, and look-up table method is also vulnerable to memory address side channel attack. However, our method is establishing the scalar multiplication in 0.35s with high security against both attacks. Copyright © 2015 John Wiley & Sons, Ltd.

Abstract Multi‐precision squaring is one of the performance‐critical operations for implementation of elliptic curve cryptography. This paper continues the line of research on high‐speed multi‐precision squaring on embedded processors. In particular, we present an optimized Karatsuba squaring method for 8‐bit AVR processors. We compute the multiplication part with the fastest Karatsuba multiplication, and then the remaining two squaring parts are conducted with the fastest sliding block doubling squaring. As a result, The proposed method sets the new speed records for multi‐precision squaring, improving the execution time by up to 8.49% compared with the best known works. Copyright © 2015 John Wiley & Sons, Ltd.

SUMMARY Rational party is a new kind of parties who behave neither like honest parties nor like malicious adversaries. The crux point of rational party is the definition of the utility function, as rational parties only care about how to maximize their utility. In other words, rational parties choose the strategies, which can bring them the highest utilities. In rational secure two‐party computation protocol, the main task is how to boost mutual cooperation to complete the protocol. Social rational secure multi‐party computation (SRSMPC) means that in a social network, some distributed and rational parties with reputation properties want to jointly compute a functionality. The seemingly simple task becomes tough under three conditions. The first condition is that the network composed by parties may not be complete. That is, two parties may not be neighbors and they are connected through other parties. The second is that the network may be not secure. That is, messages may be tempered by malicious parties. The third condition is that parties may run the protocol under incomplete information scenario. That is, parties may have types and each type has a corresponding utility function. Under the first and second conditions, parties need to consider how to securely transmit messages between two parties who are not neighbors. Under the third condition, we propose the Tit‐for‐Tat strategy and prove that mutual cooperation is a sequential equilibrium between two parties. In this paper, we construct an SRSMPC protocol by using mechanism design under incomplete information to facilitate the implementation of the SRSMPC protocol within constant rounds. Meanwhile, newcomers are allowed to participate in the protocol. To the best of our knowledge, this is the first social rational secure computation protocol for multi‐party under an incomplete information scenario and an incomplete network. Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, we redefine the utilities considering other parts such as reputation in order to give rational parties incentives to participate in the protocol and finally get the correct outputs. The most distinct contribution of this paper is the proposal of rational covert adversaries whose behaviors are combinations of rational parties and covert adversaries. Finally, given proper parameters, we prove that all parties have incentives to participate in the rational secure computation protocol. Copyright © 2013 John Wiley & Sons, Ltd.