An Efficient and Secure Anonymous Authentication Scheme for VANETs Based on the Framework of Group Signatures

Vehicular ad hoc networks (VANETs) have stimulated interests in both academic and industry settings. Once deployed, they would bring a new driving experience to drivers. However, in an open-access environment, privacy is one of the greatest challenges, as drivers want to keep their personal information protected. Therefore, many authentication protocols have been proposed as solutions to the privacy issue. In most of the existing protocols, to prevent the revoked entity from generating a valid authentication information, the verifiers must frequently download the revocation list from one or more remote authorities to keep the list up-to-date, which greatly increases the workload of the remote authority. In this paper, to cope with such challenging concerns, based on the idea of group signatures, we propose a novel authentication protocol scheme by using the complete sub-tree method to achieve membership revocation, which ensures forward security. In our scheme, the verifiers can verify the authentication information by getting the latest epoch $t$ without having to obtain the latest revocation list. In the aspect of security, the proposed protocol is featured with forward security, CCA2-anonymity, unforgeability, non-frameability, and traceability. In addition, our scheme adopts a decentralized group model, so that the whole domain of VANETs is divided into sub-regions and any vehicle has to update its non-revoked token periodically from the regional group manager who manages the region where the vehicle stays.