A Blockchain-Based Trust Management With Conditional Privacy-Preserving Announcement Scheme for VANETs

As the infrastructure of the intelligent transportation system, vehicular ad hoc networks (VANETs) have greatly improved traffic efficiency. However, due to the openness characteristics of VANETs, trust and privacy are still two challenging issues in building a more secure network environment: it is difficult to protect the privacy of vehicles and meanwhile to determine whether the message sent by the vehicle is credible. In this article, a blockchain-based trust management model, combined with conditional privacy-preserving announcement scheme (BTCPS), is proposed for VANETs. First, an anonymous aggregate vehicular announcement protocol is designed to allow vehicles to send messages anonymously in the nonfully trusted environment to guarantee the privacy of the vehicle. Second, a blockchain-based trust management model is present to realize the message synchronization and credibility. Roadside units (RSUs) are able to calculate message reliability based on vehicles' reputation values which are safely stored in the blockchain. In addition, BTCPS also achieves conditional privacy since trusted authority can trace malicious vehicles' identities in anonymous announcements with the related public addresses. Finally, a mixed consensus algorithm based on proof-of-work and practical Byzantine fault tolerates algorithm is suggested for better efficiency. Security analysis and performance evaluation demonstrate that the proposed scheme is secure and effective in VANETs.