Blockchain-based conditional privacy-preserving authentication scheme in VANETs

In vehicular ad hoc networks (VANETs), a vehicle must be authenticated to ensure its messages’ correctness. The authentication mechanism should be privacy-preserving to protect the vehicle’s real identity. However, an authenticated vehicle may misbehave, which forms the basis for certificate revocation lists (CRLs) requirement. But, the CRLs need a large storage and communication overhead. The difficulties like the huge computation overhead, the heavy burden of storing and managing pseudo-identities, and handling ever-increasing certificate revocation makes the existing authentication schemes impracticable. To overcome these difficulties, we propose a hybrid blockchain-based conditional privacy-preserving authentication (BCPPA) scheme in VANETs. In BCPPA, vehicles obtain pseudo-identities from the trusted authority that manages the network. A vehicle uses the received pseudo-identities to achieve anonymous authentication and communicate with other network members. The pseudo-identities with encrypted, real identities are both saved into the blockchain to ensure conditional privacy and member revocation. A receiver can verify the sender’s pseudo-identity using the proposed privacy-preserving authentication mechanism. We evaluate the scheme’s performance using the Ethereum blockchain and computing platform. The security analysis and experimental results show that the proposed scheme is effective in providing authentication and privacy and has reduced computation overhead as compared to existing schemes.