Privacy-preserving batch verification signature scheme based on blockchain for Vehicular Ad-Hoc Networks

Along with the development of Internet of Things (IoT) technology and Vehicular Ad-Hoc Networks (VANETs), security and effectiveness of road utilization have also been greatly improved. Currently, many certificateless signature schemes have been proposed to improve the communication speed while protecting the communication contents and real identities of the vehicles. Among others, some schemes realize batch verification or aggregation of multiple signatures. However, they either incur high calculation costs or cannot execute the operation of batch verification successfully. In this paper, we propose an efficient and privacy-preserving certificateless public key signature scheme based on the blockchain. Firstly, our scheme provides support for batch verification and aggregation of the signatures, and has lower calculation cost compared with the previous ones. Secondly, our scheme adds two blockchains to the structure in order to protect the identity privacy of the vehicles. Utilizing the immutability and openness of the blockchain, all nodes in VANETs can verify whether the identity of the vehicle is legal. Therefore, the scheme can greatly reduce the risk of privacy disclosure, and the pseudo-identities can be generated by the vehicles themselves. Thirdly, our scheme can realize traceability of the vehicles, which means the real identities of the vehicles can be revealed if they commit an illegal behavior. The experimental results show that our scheme can greatly reduce the computational cost of the vehicles and provide the functions of batch verification and aggregation. Therefore, the proposed scheme can simultaneously improve security and efficiency of the signature schemes for VANETs.