With the rapid development of artificial intelligence and big data technologies, gait recognition has become a key method for identity authentication. As a unique biometric characteristic, gait is difficult to counterfeit and supports long-distance, non-contact authentication, making it ideal for security, surveillance, and health monitoring. However, traditional gait authentication faces privacy and efficiency challenges. This paper presents a privacy-preserving gait authentication scheme based on partial Euclidean distance calculation, and the scheme encrypts gait features using block-diagonal orthogonal matrices and random perturbation vectors, enabling efficient encrypted computation on the cloud. Experimental results demonstrate that the proposed scheme improves processing efficiency and matching accuracy while protecting privacy. For instance, on the CASIA-B dataset, it reduces computation time by approximately 30% without compromising accuracy.

In the field of machine learning, PCA based face recognition is widely applied in identity authentication and access control. Due to limited storage and computational capabilities, the client often needs to outsources face recognition tasks to cloud servers, which brings privacy leakage risks. Existing privacy-preserving schemes calculate the inner product of encrypted vectors to perform face matching, but they involve complex operations, making efficient recognition challenging and lacking in automatic verification of computational integrity. In this paper, we propose a blockchain-aided privacy-preserving PCA based face recognition scheme. Our approach uses sparse matrices to construct keys, reducing the number of non-zero elements in matrix operations. The scheme also introduces a blockchainaided verification and payment mechanism based on hash commitments to verify the integrity of computation tasks. This mechanism allows encrypted face images and face recognition results to be uploaded to the blockchain, effectively reducing the number of interactions between the client and the cloud server. Experimental results demonstrate that this scheme reduces the overall execution time by 43% without compromising recognition accuracy, achieving a recognition accuracy rate of 99.35%.

Lattice-based Post-Quantum Cryptography (PQC) can effectively resist the quantum threat to blockchain's underlying cryptographic algorithms. Blockchain node decryption is one of the most commonly used cryptographic computations in blockchain systems, and polynomial multiplication, a time-consuming operation for decryption, is one of the factors limiting blockchain efficiency. This paper proposes a novel distributed computing algorithm for polynomial multiplication, applicable in blockchain decryption. By splitting polynomials into lower-degree terms and delegating tasks to distributed nodes, our approach reduces computation time. A novel verification strategy based on the Karatsuba algorithm ensures result accuracy. The experimental results demonstrate that our proposed scheme improves the execution efficiency of NTT and INTT operations by approximately 47.8% and 52.4%, and reduces Kyber decryption time by up to 23.5%.

Cloud-assisted computation empowers resource-constrained clients to efficiently tackle computationally intensive tasks by outsourcing them to resource-rich cloud servers. In the current era of Big Data, the widespread need to solve large-scale modular linear systems of equations ($\mathcal {LMLSE}$) of the form$\mathbf {A}\mathbf {x}\equiv \mathbf {b}\;{\rm mod}\;{q}$poses a significant challenge, particularly for lightweight devices. This paper delves into the secure outsourcing of$\mathcal {LMLSE}$under a malicious single-server model and, to the best of our knowledge, introduces the inaugural protocol tailored to this specific context. The cornerstone of our protocol lies in the innovation of a novel matrix encryption method based on sparse unimodular matrix transformations. This novel technique bestows our protocol with several key advantages. First and foremost, it ensures robust privacy for all computation inputs, encompassing$\mathbf {A},\mathbf {b}, q$, and the output$\mathbf {x}$, as validated by thorough theoretical analysis. Second, the protocol delivers optimal verifiability, enabling clients to detect cloud server misbehavior with an unparalleled probability of 1. Furthermore, it boasts high efficiency, requiring only a single interaction between the client and the cloud server, significantly reducing local-client time costs. For an$m$-by-$n$matrix$\mathbf {A}$, a given parameter$\lambda =\omega (\log q)$, and$\rho =2.371552$, the time complexity is diminished from$O(\max \lbrace m n^{\rho -1}, m^{\rho -2} n^{2}\rbrace \cdot (\log q)^{2})$to$O((mn+m^{2})\lambda \log q+mn(\log q)^{2})$. The comprehensive results of our experimental performance evaluations substantiate the protocol's practical efficiency and effectiveness.

In recent years, Bitcoin has become one of the most popular cryptocurrencies. The most significant mechanism of Bitcoin is PoW (Proof-of-Work), but it also brings opportunities for mining attacks. In our last study, we proposed a Selfish Mining-based Denial-of-Service Attack (SDoS), which can cause serious threats to the Bitcoin system. On this basis, we further put forward three greedier SDoS attack strategies: a competitive greedy SDoS attack strategy ESDoS, a trail greedy SDoS attack strategy TSDoS, a hybrid greedy SDoS attack strategy ETSDoS, and a more public SDoS attack strategy PSDoS. Besides, we also study the adversary’s optimal strategies under different conditions. The experimental results show that if the adversary adopts the SDoS optimal strategy, his revenue increase rate will be further improved and significantly higher than the other existing mining attacks. If the adversary masters 14% of the total mining power, he has a chance to improve his revenue (25% in Selfish Mining, 19.6% in SDoS), and if the adversary masters 15% of the total mining power, he is capable of launching a 51% attack.

The advent of 6G communications technology will bring about a transition from the “Internet of Everything” to the “Intelligent Connection of Everything”. 6G-enabled vehicular ad hoc networks (VANETs) will enjoy lower latency, higher speed, and greater capacity network services. Nevertheless, achieving secure data sharing will be an even tougher challenge. Given this, we propose an attribute-based data sharing scheme with blockchain for 6G-enabled VANETs. First, we propose an efficient multi-tree-based user revocation mechanism. With the Chinese remainder theorem, our mechanism supports user batch revocation and batch joining. Second, we achieve distributed data storage by utilizing the blockchain and smart contracts. To solve the problem of insufficient storage capacity on the blockchain, we adopt a combination of on-chain and off-chain storage. Third, to reduce the computation burden on users, our proposal supports online/offline encryption and verifiable outsourced decryption. Meanwhile, our mechanism supports policy hiding, data revocation, and cross-domain data sharing. The proposed scheme is proven to satisfy the indistinguishability under chosen plaintext attack (IND-CPA) in the standard model. Theoretical analysis shows that our mechanism outperforms existing schemes in functionality and security. Simulation experiments show that our proposal is efficient and suitable for 6G-enabled VANETs.

Vehicular fog computing (VFC), as an extended model of fog computing, combines fog computing with traditional in-vehicle networks to provide real-time response services for users. However, in such a dynamic system architecture, achieving secure and efficient data sharing is an enormous challenge. Ciphertext-policy attribute-based encryption (CP-ABE) is widely regarded as an excellent way of achieving one-to-many data sharing. Nevertheless, several practical challenges hinder its widespread application in VFC, such as inefficient attribute revocation, single-factor access control, and centralized data storage. For this purpose, we design a multifactor combined data sharing scheme for VFC with CP-ABE and blockchain (MC-DS-VFC, in short). We first propose an efficient attribute revocation mechanism that does not require complex key update operations. We then embed time, user attributes, and access interests into data sharing for more fine-grain access control, which enables users with sufficient attributes to efficiently access real-time shared data according to their access interests. Finally, we combine the interplanetary file system (IPFS) and the blockchain maintained by roadside units (RSUs) to achieve distributed collaborative storage. Furthermore, our mechanism also supports user traceability, attribute joining, online/offline encryption, and verifiable outsourced decryption. Our proposal is shown to satisfy the indistinguishability under chosen plaintext attack (IND-CPA) in the standard model. Theoretical analysis and simulation experiments indicate that the MC-DS-VFC scheme is efficient and practical for VFC.

Abstract The rectangle attack is the extension of the traditional differential attack and is evolved from the boomerange attack. It has been widely used to attack several existing ciphers. In this article, we study the security of lightweight block ciphers GIFT, Khudra and MIBS against related-key rectangle attack. We use Mixed-Integer Linear Programming-aided cryptanalysis to search rectangle distinguishers by taking into account the effect of the ladder switch technique. For GIFT, we build a 19-round related-key rectangle distinguisher and attack on 23-round GIFT-64, which requires 260 chosen plaintexts and 2107 encryptions. For Khudra, a 14-round related-key rectangle distinguisher can be built, which leads us to a 17-round rectangle attack. Our attack on 17-round Khudra requires a data complexity of 262.9 chosen plaintexts and a time complexity of 273.9 encryptions. For MIBS, we construct a 13-round related-key rectangle distinguisher and propose an attack on 15-round MIBS-64 with time complexity of 259 and data complexity of 245. Compared to the previous best related-key rectangle attack, we can attack one more round on Khudra and MIBS-64 than before.

There are two nonzero cross-components of a triaxial induction logging tool in the medium coordinate system in a transversely isotropic (TI) formation. The sum of the cross-components holds dependence on only the horizontal conductivities with little nonlinearity and small shoulder bed effect in a horizontally layered formation. Based on the generalized reflection coefficient method, simplified formulas of the sum are derived to analyze its response characteristics. Numerical results show that the apparent conductivity obtained from the sum is a square-looking log with high vertical resolution. Moreover, the readings almost equal to the true horizontal conductivity of the formation beds. These characteristics can be applied to reconstruct the horizontal conductivity and the formation boundaries with triaxial induction logging data.

Different from identity-based encryption scheme, an attribute-based encryption scheme is a scheme in which each user is identified by a set of attributes, and some function of those attributes is used to determine decryption ability for each ciphertext. But key escrow problem is also the inherent problem in attribute-based encryption scheme. To avoid the problem of key escrow, this paper presents an attribute-based encryption scheme by use of another secret key that the KGC cannot obtain. Following, based on a concrete attribute-based encryption scheme insecure against malicious KGC, we give a scheme secure against malicious KGC. Furthermore, compared with the original scheme, our scheme doesn't increase the length of the public key and the ciphertext. The security of our scheme is obtained directly from the security of the original scheme.

Three-dimensional (3-D) integration of systems by vertically stacking and interconnecting multiple materials, technologies, and functional components offers a wide range of benefits, including speed, bandwidth and density increase, power reduction, small form factor, packaging reduction, yield and reliability increase, flexible heterogeneous integration with multifunctionality, and overall cost reduction. A new spectrum of opportunities and challenges arises for integrated system designers, which warrants rethinking and innovations from system design perspectives. By selecting three representative cases, i.e., solid-state data storage, power delivery, and hybrid radio-frequency/optical transceiver for distributed sensor networks, this paper intends to exemplify the potentials of exploiting the benefits of 3-D integration technology from system perspectives.

Identity-based crypto system has many advantages over PKI-based cryptosystem in key distribution, but key escrow is always an inherent drawback. In order to solve the problem, certificateless public key cryptography was introduced by Al-Riyami and Paterson in [8]. In this paper, we first introduce a certificateless signature scheme secure against both malicious PKG attack and DOD attack without random oracle, which is the first scheme satisfying theses properties in the literature. Based on the certificateless signature scheme, we also present a constant-size group signature scheme against malicious group manager.