PBAG: A Privacy-Preserving Blockchain-Based Authentication Protocol With Global-Updated Commitment in IoVs

Internet of Vehicles (IoVs) is increasingly used as a medium to propagate critical information via establishing connections between entities such as vehicles and infrastructures. During message transmission, privacy-preserving authentication is considered the first line of defence against attackers and malicious information. To achieve a more secure and stable communication environment, ever-increasing numbers of blockchain-based authentication schemes are proposed. At first glance, existing approaches provide robust architectures and achieve transparent authentication. However, in these schemes, verifiers need to conduct real-time operations in the blockchain (e.g., querying certificates). To remedy this limit, we propose a privacy-preserving blockchain-based authentication protocol with global-updated commitment (PBAG). In PBAG, based on the issued certificates, a public global commitment is computed, and a unique evaluation proof is generated for each authorized vehicle. Instead of querying the blockchain in real-time, verifiers can independently authenticate vehicles using the global commitment that is pre-updated with the assistance of the blockchain. Moreover, our scheme proposes a dynamic update mechanism to ensure the freshness of the global commitment and evaluation proofs. Benefiting from the update mechanism, there will be an authentication failure for vehicles holding invalid certificates when using the latest global commitment, thus avoiding the time-consuming of checking the Certificate Revocation List (CRL). In terms of privacy protection, our scheme provides privacy properties such as anonymity and unlinkability. It allows anonymous authentication based on evaluation proofs and achieves traceability of identity in the event of a dispute. The simulation demonstrates that the average computation cost of verifying per message is 0.36ms under the batch-enabled mechanism, reducing by more than 63.7% compared with existing schemes.