EAKM: Efficient Conditional Privacy-Preserving Authentication Scheme with On-Chain Key Management in VANETs

Conditional privacy-preserving authentication can provide anonymity and traceability to Vehicular Ad-Hoc Networks (VANETs), which protects users' privacy while resisting malicious users and false messages. However, existing schemes suffer from various disadvantages, such as unavailable batch verification, unrenewable user public keys/certificates, and untimely revocation. In this work, we design an efficient conditional privacy-preserving authentication scheme with the on-chain key management (EAKM) for VANETs. To achieve lightweight authentication, we design an efficient Signature of Knowledge (SoK) and a batch verification algorithm. Moreover, we use the hash chain technology to update users' anonymous public keys. In addition, based on the blockchain technology and smart contract, we could manage users' anonymous public keys efficiently and transparently. Security analysis and simulation results show that EAKM ensures conditional privacy with less authentication overhead.