An Efficient Conditional Privacy-Preserving Authentication Protocol Based on Generalized Ring Signcryption for VANETs

With the rapid development of the Internet of Things (IoT), vehicular
ad hoc
networks (VANETs) have gradually become a research hotspot. A number of Conditional Privacy-preserving Authentication (CPPA) schemes have been proposed to protect the security and privacy of the VANETs communication. However, most of them can only provide one function between signature and signcryption, making it difficult to meet the needs of complex application scenarios. Moreover, the majority of CPPA schemes allow a Trusted Authority (TA) to expose the malicious message's sender, but they can hardly prove the authenticity of the tracking result. Therefore, we propose a new CPPA protocol to solve these problems. In our protocol, generalized ring signcryption is introduced to provide ring signature mode and ring signcryption mode in one algorithm to satisfy the different security requirements in complex application scenarios. A convenient public verification algorithm is designed to make the tracking result provable and more credible. Furthermore, we prove that our protocol achieves confidentiality, unforgeability, and Known Session-Specific Temporary Information Security (KSSTIS). We also introduce pseudonyms in our protocol to resist the ring selection attack. The performance analysis shows that our protocol has at least 61.84% improvement in computational cost compared with several similar schemes.