Blockchain technology, renowned for its decentralized and secure nature, has gained substantial attention. Central to its functionality are consensus mechanisms, which are essential for validating transactions and upholding the integrity of the distributed ledger. However, the efficiency and scalability of blockchain are currently impeded by the resource limitations and excessive communication demands of existing consensus mechanisms. To address these challenges, we propose GT-BFT, a streamlined and lightweight blockchain consensus mechanism grounded in a global trust model. This model capitalizes on node behavior to form consensus groups and facilitate consensus achievement. GT-BFT integrates a novel approach of selective broadcasting along with a Byzantine threshold determination algorithm, significantly boosting both the efficiency and security of the network. Our extensive analysis and performance evaluation reveal that GT-BFT surpasses existing mechanisms in key areas such as security, system throughput, and transaction confirmation speed, marking a significant advancement in blockchain consensus technology.

With the rapid proliferation of crowd mobility data produced by ubiquitous mobile devices equipped with spatial positioning modules, deep neural networks (DNNs) have become widely applied in spatio-temporal trajectory modeling. However, recent studies have shown that DNNs are vulnerable to adversarial examples with strong transferability, which are crafted by introducing small perturbations to original examples but can cause catastrophic mistakes. To mitigate this vulnerability and enhance model robustness, we propose a novel self-supervised collaborative learning framework named Auto-GAN that consists of a generator for automatically learning robust latent features and a discriminator for providing comprehensive guidance to the generator. By leveraging the collaboration between the generator and discriminator, our proposed method significantly improves the denoising performance. Moreover, we combine point-level and feature-level constraints into training processes between original example reconstruction and adversarial example denoising, thereby effectively suppressing the potential “error amplification effect". Extensive experiments conducted on two representative real-world mobility datasets show that our proposed method can significantly enhance the model’s robustness against various adversarial attacks, while preserving the model’s prediction accuracy on original examples.

Simulating human mobility realistically and generating large-scale, high-quality trajectories are crucial for various location-based applications such as traffic management, epidemic spreading analysis, and location privacy protection. While the most popular model-free methods succeed by directly learning distribution of real-world data, they struggle to produce high-quality mobility data without leveraging the domain knowledge of human mobility. Moreover, such model-free methods primarily rely on auto-regressive paradigms, usually accompanied by error accumulation problem. To address the issues, we propose a model-free Domain-Knowledge Enhanced Generative Adversarial Network (DKE-GAN), which efficiently combines domain knowledge of urban context with model-free learning paradigm to generate high-quality mobility data. In addition, we incorporate reinforcement learning into the training process, thereby effectively alleviating the error accumulation. Furthermore, we introduce Trajectory Representation Learning (TRL) to convert noise-carrying raw trajectories into low-dimensional representation vectors for fully mining human mobility patterns. Extensive experiments conducted on two representative real-world mobility datasets demonstrate that our proposed method outperforms six state-of-the-art baselines, significantly achieving performance improvements in simulating human mobility.

In the Internet of Things (IoT) scenario, the device diversity and data sparsity present a significant challenge for malicious traffic detection, notably the “small sample problem” where insufficient data hampers the performance of the deep learning methods that depend on large volumes of labeled data for training. Transfer learning (TL) has the capability to transfer knowledge from a label-rich but heterogeneous domain to a label-sparse domain, making it a powerful tool for addressing challenges in IoT malicious traffic detection. To address these challenges, we introduce the EMTD-SSC model, a novel enhanced malicious traffic detection model that leverages TL under small sample conditions in IoT environments. Initially, our approach includes a comprehensive labeled data set that merges a small-scale IoT intrusion detection domain with the traditional intrusion detection domain to enrich semantic information transfer from the source to target domains. The EMTD-SSC model employs dual residual convolutional autoencoders for robust feature extraction and transfer, incorporating skip connections to expedite the model convergence and minimize information loss. Furthermore, to optimize transfer efficiency, we minimize the multilayer multi kernel maximum mean discrepancy (MLMK-MMD) across corresponding network layers, facilitating effective domain adaptation. Through unsupervised training and subsequent fine tuning on the target domain data, the model significantly enhances anomaly detection capabilities. Extensive experiments on the two well-known public data sets demonstrate that the EMTD-SSC model’s effectiveness, achieving an impressive 94.8% accuracy in the binary classification tasks.

Insider threats represent a significant challenge in both corporate and governmental sectors. Most existing supervised learning based detection methods that rely on transforming user behavior into sequential data do not fully utilize structural information and require extensive labeled data. This reliance poses a challenge due to the scarcity of labeled data in real-world scenarios, leading to a few-shot learning situation. To address these limitations, we propose a novel Graph modularized-based Meta-learning Framework for Insider Threat Detection, named GMFITD. Specifically, GMFITD utilizes a structural reconstruction mechanism that combines a graph-based autoencoder with an attention mechanism to explore structural information and infer potential relationships between users. Additionally, we employ a graph prototype construction method coupling episodic meta-learning principle (MAML) to compute representative embeddings for few-shot learning scenarios. By leveraging MAML, the proposed method can capture prior knowledge of insider threat classification by training on similar few-shot learning tasks with few labeled samples. We further enhance the resilience of GMFITD to adversarial attacks through an edge importance estimation mechanism, which assigns higher weights to relevant edges. Extensive experiments demonstrate that our proposed GMFITD outperforms state-of-the-art methods in insider threat detection, achieving higher accuracy with fewer labeled samples and resisting adversarial attacks.

Federated learning aims to complete model training without private data sharing, but many privacy risks remain. Recent studies have shown that federated learning is vulnerable to membership inference attacks. The weight as an important parameter in neural networks has been proven effective for membership inference attacks, but it leads to significant overhead. Facing this issue, in this paper, we propose a bias-based method for efficient membership inference attacks against federated learning. Different from the weight that determines the direction of the decision surface, the bias also plays an important role in determining the distance to move along the direction. Moreover, the number of bias is way less than the weight. We consider two types of attacks: local attack and global attack, corresponding to two possible types of insiders: participant and central aggregator. For the local attack, we design a neural network-based inference, which fully learns the vertical bias changes of the member data and non-member data. For the global attack, we design a difference comparison-based inference to determine the data source. Extensive experimental results on four public datasets show that the proposed method achieves state-of-the-art inference accuracy. Moreover, experiments prove the effectiveness of the proposed method to resist some commonly used defenses.

Insider threats present a formidable challenge to cybersecurity, as insiders possess the privileges and information necessary to execute diverse attacks. A comprehensive analysis of user behavior, including behavioral features, sequences, and inter-user relationships, is required for effective insider threat detection. However, few existing methods consider these features in an integrated manner, which could result in high false positives. To further improve the accuracy of insider threat detection, we propose a novel framework for insider threat detection based on a temporal graph convolutional network with data augmentation (referred to as TGCN-DA), which integrates the exploration of structural information among users and simultaneously captures the behavior temporal dependencies. In particular, we introduce an edge predictor to encode user structural information and strengthen intra-class edges among users based on the representation of users’ behavior. Additionally, the GCN with temporal feature mechanism is leveraged to learn dynamic changes in users’ behavior to capture behavior temporal dependence. Extensive experiments demonstrate that our proposed TGCN-DA outperforms other state-of-the-art methods and achieves higher accuracy in the task of insider threat detection.

The rapid development of the Internet and the increasingly complex structure of network space make the network security situation more and more serious. Abnormal traffic detection is an important part of network intrusion detection and plays an important role in the field of network security. Traditional machine learning methods rely too much on feature selection and extraction and have high false positive rate and delay caused by abnormal behavior recognition. Deep learning models such as CNN and RNN have many parameters and long training time, which seriously affect the early warning function of network intrusion detection. Aiming at the problem that the parameter redundancy of deep learning models limits the corresponding model deployment in some scenarios and devices, this paper proposes a lightweight bit-operation abnormal traffic detection method based on XNOR-net convolutional neural network (XNOR-CNN). The model uses convolutional neural network(CNN) and long-short term memory(LSTM) to comprehensively analyze the temporal and spatial characteristics of network traffic, and predicts and classifies the attack behaviors in the future network traffic. In particular, the model transforms the complex convolution process into bit operation between vectors by XNOR operation, which reduces the storage of weight vectors and complex redundant calculation, greatly improves the speed of network training and reduces the consumption of network memory. In this paper, the accuracy and efficiency of XNORCNN model are proved through a large number of comparative experiments on real traffic datasets.

In the era of Internet of Things (IoT), millions of heterogeneous IoT devices generate an explosion of data and services waiting to be discovered. The convergence of IoT with social networks (SIoT) interconnects multiple IoT applications and alleviates the common data sparsity and cold start problems in traditional recommendation systems. However, the social trust relationships may also be very sparse, which affects the accuracy of trust-based recommendation systems. Meanwhile, mobile devices have limited resources and are more vulnerable to malicious attacks in the IoT environment. In order to complete the trust relationship and further improve the trust-based recommendation performance, we propose a reliable and lightweight trust inference model for service recommendation in SIoT, calledTIRec. First, we obtain a comprehensive weighted centrality metric (LGWC) considering both local and global contexts. Based on this, we propose a corresponding lightweight trust path selection algorithm. Then, we present a reliable trust inference calculation algorithm consist of trust propagation and aggregation strategy, which can efficiently resist two common malicious attacks. Finally, we incorporate the rating, direct trust, and indirect trust together into the matrix factorization model, and integrate the influence of truster and trustee to obtain the synthetic model for rating predication. To the best of our knowledge, this article is the first to integrate trust inference algorithm into the trust-based recommendation systems. The extensive experiments are conducted on three real-world data sets, and the results show that ourTIRecmodel performs better than other advanced recommendation models in both “all users” view and “cold start users” view.

The integration of trust system and recommendation system is a new hot spot in current research. Trust relationship has be exploited in social recommendation, which can effectively solve the problems of low recommendation quality, sparse data and cold start in the traditional recommendation system. Meanwhile, trust inference in social relations is necessary in completing trust information and expanding social recommendation knowledge base. In this work, we propose a new trust inference algorithm LWCTrust to improve the efficiency and accuracy of social recommendation. Firstly, we construct a local weighted centrality (LWC) metric based on the user's degree centrality and trust information, and propose a new adaptive breadth-first search algorithm. Then, based on the property of path decay, we compare two different trust decay strategies. In addition, considering inconsistencies and conflicts in trust opinion, we apply LWC metric to multi-path aggregation step and present a OWA dynamic aggregation strategy. A number of experiments are conducted on the real social network dataset Advogato, and the results validate the great performance of LWCTrust. Our work is the first to construct an efficient LWC metric using social graph trust information, and we explore the effect of attenuation functions on accuracy in path propagation.

Today, the scale of global Internet users continues to grow; the Internet has become the main driver of global economic growth; IoT technology is also constantly pushing the process of the Internet of Everything. However, the ever-changing cybersecurity situation is not optimistic and the people's demand for secure network is also increasing. In this paper, for the biggest challenge of building anomaly-based Network Intrusion Detection System: building a high-performance intrusion detection classifier model, we first propose an effective intrusion detection method based on pruning deep neural network: P-DNN. Firstly, we train a deep neural network with complex structure and good intrusion detection performance. Secondly, through the pruning operation, only the connections with more important information in the weight are reserved, reducing the complexity of the model. Finally, retrain the deep neural network to find the best model. We use the KDD Cup 99 dataset to evaluate the effectiveness of the method and achieve exciting results. The model constructed by P-DNN achieves a detection rate of 0.9904 for known attacks and a detection rate of 0.1050 for unknown attacks. By comparing with related work, the model achieves the best intrusion detection performance: COST is reduced to 0.1875 and ACC is increased to 0.9317.