Nowadays, as an essential technique for intelligent transportation, vehicular ad hoc networks (VANETs) has significantly improved people’s travel experience, providing richer, and smarter services for vehicles while ensuring driver safety. However, considering that VANETs are complex, some security challenges still remain, including but not restricted to privacy preserving of vehicles, authentication of messages, limited resources in computational power, and network bandwidth. To address these issues, many privacy-preserving identity authentication schemes for VANETs have been proposed recently. However, these schemes still suffer some limitations. First, their computational overheads are heavy due to the complex calculations. Second, some schemes are vulnerable to various security weaknesses, unable to resist normal attacks. Third, in some schemes, the same pseudonym keeps unchanged and it is linked to the corresponding private key of user. The consequence is that if the user wants to change its pseudonym, the corresponding private key must be changed. In order to further solve the above problems, we propose a novel privacy-preserving identity authentication protocol based on the certificateless aggregate signature scheme, allowing the user to generate a fuzzy identity to hide her real identity, and the private key can be kept unchanged even if the corresponding pseudonym is updated. Furthermore, to achieve efficiency in computation, bilinear mapping is avoided in our proposed scheme. We prove that our protocol satisfies unforgeability in the random oracle based on a classic complexity assumption. Finally, the security and efficiency analyses demonstrate that our construction enjoys more security features and better performance compared with the existing schemes.

In recent years, the development of Internet of Things technology has led to a surge in interest in the Vehicular Ad-Hoc network (VANET), which has greatly improved travel efficiency and facilitated vehicle data sharing. To ensure the privacy and security of both vehicles and personnel, researchers have proposed various measures for securing VANET systems. Recently, certificate-based aggregate signature (CBAS) schemes have been proposed to design an identity authentication protocol for the VANET to prevent tampering and corruption of private vehicle data. In this study, we conduct a security analysis of the previous CBAS scheme by presenting a security attack. Afterward, we propose a novel and concrete construction of the CBAS scheme that offers improved performance for VANET, which can enhance protection in the VANET scenario. We also demonstrate its security based on standard cryptographic assumptions. Comparative results from theoretical analysis and experimental evaluation illustrate the practicality of our proposed scheme. Similarly, the identity authentication protocol created based on the above CBAS scheme has the properties of dynamic anonymity, mutual identity authentication, unforgeability.

The Internet of Things (IoT) is helpful in making people's life more convenient and efficient. To ensure that the nodes within IoT can interact securely, a certificateless signature (CLS) can be used to protect message authentication in the IoT. Recently, some concrete constructions of CLS schemes have been proposed in the literature, but through our analyses, we demonstrate that some existing CLS schemes cannot keep their claimed security because of various security flaws. For example, a valid signature can be forged by any Type I adversary by replacing the corresponding user's public key. In this article, we describe the security flaws that need to be addressed and introduce a novel CLS scheme without using bilinear mapping. The existential unforgeability in our proposed scheme can be proved based on the hardness of the elliptic curve discrete logarithm problem in the random oracle model. The comparison with existing CLS schemes shows that our scheme not only enjoys more security features but also is more efficient in computation. Moreover, we introduce an identity authentication protocol as the application of our proposed CLS scheme, which achieves mutual authentication and anonymity in communications.

In future intelligent transportation systems, vehicular ad hoc network (VANET) is a popular application. They provide early warning of dangers through wireless communication to improve road safety. Therefore, we should protect messages from leakage and changes during transmission. To ensure the security issues in the communication process, we propose a secure and effective certificateless signcryption scheme with multiple messages and multiple receivers and prove its confidentiality and unforgeability based on the hardness of the discrete logarithm problem and the computational Diffie Hellman problem. Our scheme implements the signature and encryption of multiple messages for different receivers and achieves anonymity for the receiver. Based on our signcryption scheme, we design an identity authentication and key agreement protocol applying the construction in VANET. In addition, we also point out that through comprehensive performance analysis, our proposal has higher security and efficiency of computation and communication compared to other signcryption constructions.