Efficient Certificateless Aggregate Designated Verifier Signature With Conditional Privacy Preserving in VANETs

Vehicular ad hoc networks (VANETs) serve as the foundation of intelligent transportation systems, aiming to improve communication efficiency and safety among vehicles. With the expanding applications, security and privacy have become apparent, and the large-scale message transmission imposes substantial computation and communication overheads. The technology of aggregate signature can realize message authentication and reduce both the bandwidth and computation costs significantly. In IEEE 802.11p-based VANETs, most existing aggregate signature schemes require roadside units (RSUs) to verify single signatures before calculating aggregate signatures, which is very inefficient. Furthermore, even with a valid aggregated signature, the validity of individual signatures cannot be assured. In this paper, we propose an efficient certificateless aggregate signature scheme, where RSUs do not need to validate single signatures but compute aggregate signature directly. The successful verification of the aggregated signature implies the validity of each individual signature. Additionally, to further protect data security and user privacy, this scheme employs designated verifiers for both individual and aggregate signatures. Both formal and informal security analysis are given, and performance evaluation shows our scheme exhibits lower computation and communication costs, along with more comprehensive security attributes in VANETs.