Vehicular ad-hoc networks (VANETs) have drawn a lot of attention for their potential to improve traffic efficiency and safety. To deal with anonymous authentication and message integrity during communication, many protocols have been designed. One important approach is using Ring Signature to obtain superior security and better efficiency. However, most of the previous Ring Signature-Based authentication protocols could not support the Trusted Authority (TA) to revoke the vehicle user's identity whenever it wanted. In this paper, we solve this problem and realize Conditional Privacy-Preservation Authentication successfully. As part of our work, we propose the first Lattice-based Revocable Ring Signature scheme, and prove its security under the random oracle model, which could be of independent interest. It is quantum-resistant, highly efficient, and suitable for scenarios where the TA needs to be accountable. Lastly, it is worth mentioning that we adopted a similar structure with the NIST signature standard CRYSTALS-Dilithium, which will increase the richness of the algorithm and standardization.

Ultra-large-scale matrix inversion has been applied as the fundamental operation of numerous domains, owing to the growth of big data and matrix applications. Using cryptography as an example, the solution of ultra-large-scale linear equations over finite fields is important in many cryptanalysis schemes. However, inverting matrices of extremely high order, such as in millions, is challenging; nonetheless, the need has become increasingly urgent. Hence, we propose a parallel distributed block recursive computing method that can process matrices at a significantly increased scale, based on Strassen’s method; furthermore, we describe the related well-designed algorithm herein. Additionally, the experimental results based on comparison show the efficiency and the superiority of our method. Using our method, up to 140,000 dimensions can be processed in a supercomputing center.

Most of the cryptographic protocols currently in use are not appropriate for Internet of Things (IoT) environments because of their huge computing overhead, especially for terminal-embedded devices with resource constrained. Moreover, the computing resources in IoT environments are frequently asymmetric, that is to say, the computing power of the terminal devices is always weak and the server side is relatively stronger. In order to guarantee the security in the scenario, we present the asymmetric computing cryptosystem. Take the key exchange protocol as an example, we show how to construct ACKE, an asymmetric computing key exchange protocol, by employing the Diffie–Hellman key exchange protocol and the Subset Product problem (NP-complete) in this article. The underlying idea this construction is to significantly decrease the computational complexity of one party, and allow for a suitable rise in the computational complexity of another party. Our proposed protocol is implemented on an IoT simulation platform composed of a notebook PC of Intel i5-5200U 2.2 GHz/8G and a smart watch of MTK6062 1.2 GHz/512M. The experimental results show that this work will assist in making the Diffie–Hellman type protocol suitable for practical applications in IoT environments.

As intelligent transportation develops by leaps and bounds, there has been a growing interest in leveraging Vehicular Ad-hoc Networks (VANETs) to improve efficiency and security. One key aspect of them is the Conditional Privacy-Preserving Authentication (CPPA) scheme, which addresses challenges of identity authentication and message integrity during communications. Most ID-Based CPPA schemes rely on Tamper-Proof Devices (TPDs), which are vulnerable to side-channel attacks. If sensitive data stored in TPDs are compromised, the entire system would be in danger. To tackle this issue, Xiong et al. introduced a CPPA scheme with double-insurance, claiming its security against adaptively chosen message attacks. However, this paper reveals that their scheme is universally forgeable, allowing anyone to create valid signatures on any message, rendering it inadequate for CPPA. In light of the weaknesses, we propose a novel scheme that inherits the time-tested Schnorr Signature and Abe-Okamoto Message Recovery Signature. Besides, we prove the security under the assumptions of Discrete Logarithms (DL) and Computational Diffie-Hellman (CDH), and conduct experiments and realistic evaluations. The results demonstrate its superiority, and establish its practicality in real-world scenarios.