CPPA-D: Efficient Conditional Privacy-Preserving Authentication Scheme With Double-Insurance in VANETs

With the establishment of the intelligent transportation system (ITS), the vehicular ad hoc networks (VANETs) play a significant role for improving traffic safety and efficiency. In order to avoid malicious attack and resource abuse in VANETs, the use of digital signature scheme is widely regarded as the first line of defense to achieve a secure VANETs system. However, it is still a challenging task to design a conditional privacy preserving authentication scheme, to resolve security and privacy-preserving problems in VANETs and to improve the utilization ratio of information resources. In addition, the relevant researches show that the tamper-proof device (TPD) is vulnerable to side channel attacks. If the sensitive parameters stored in TPD are extracted, the system would be totally broken. To address these issues, this paper introduces a conditional privacy-preserving authentication scheme with double-insurance supporting batch verification (CPPA-D) for VANETs, which is constructed in cyclic groups on elliptic curves. Either the master private key or the vehicle private key is leaked, it is impossible to forge a valid authenticated message to deceive the recipients, which achieves double-insurance for private keys. When multiple messages are received, our CPPA-D scheme allows the receiver to perform batch verification to improve the efficiency. Security analysis shows that our CPPA-D scheme not only can resist traditional attacks but also can solve the security problems caused by private key stolen in the TPD under side channel attack. There is also a certain advantage in computation overhead according to efficiency analysis and comparison.