CPPA-RORS: A conditional privacy-preserving authentication scheme based on revocable one-time ring signature for VANETs

Abstract

Vehicular ad-hoc networks (VANETs) are a wireless communication system designed to improve driving safety and traffic management, with a focus on enhancing road traffic efficiency and safety. Privacy protection is one of the crucial security challenges for VANETs. However, considering the high mobility of vehicles that frequently transmit delay-intolerant safety and informative messages, two problems exist in some ring signature-based conditional privacy-preserving authentication (CPPA) schemes for VANETs: first, vehicles cannot detect the malicious vehicles when a malicious vehicle signs a message multiple times; and second, the TAs cannot reveal vehicles’ identities when some vehicles engage in illegal activities. To address these concerns, we propose a CPPA scheme based on revocable one-time ring signature (CPPA-RORS) scheme, leveraging the properties of ring signatures. The scheme ensures anonymity of the honest vehicles while providing TAs with the ability to reveal malicious vehicles at any time. We allow one vehicle only can sign one signature on one message, called one-time, to safeguard vehicle privacy with high security. CPPA-RORS scheme provides the formal security model for VANETs, and in particular simultaneously offers message-linkability and mandatory revocability, effectively preventing the double-spending attack (Shrestha et al. 2020) and enabling TAs to revoke the anonymity of any vehicle at any time for further enhancing the security and trustworthiness of the networks. Theoretical analysis and experimental results show that CPPA-RORS provides robust security measures and privacy for vehicles in VANETs.