Privacy Protection for VANETs by Using an Efficient Revocable Message Authentication Scheme

Correctness of exchanged information and guaranteeing the privacy of vehicle owners are the two most significant security concerns for VANETs. Pseudonymous public key infrastructure (PPKI) is a practical solution to these two issues. Almost all PPKI technologies are comprehensive schemes, such as the group signature‐based and identity‐based cryptosystems. An applicable PPKI scheme for secure vehicular communication (VC) should support revocability because it is a significant functionality in VANETs to revoke certificates of vehicles for surrendering or transferring the registrations. However, the computation or space complexity in most of the revocable PPKI‐based protocols is linear when the number of vehicles or revoked vehicles increases over time. This drawback markedly degrades the efficiency and stability of secure VC. This work therefore reduces the computation complexities of authentication message verification, certificate tracing, membership revocation, and space complexity of system parameters (e.g., revocation information and public keys), such that they are independent of the number of vehicles or revoked vehicles using a novel and efficient PPKI mechanism based on bilinear mapping. The proposed scheme uses the concept of accumulator schemes and transfers the computation of accumulators from vehicles to certificate authority (CA) for achieving constant computation and storage complexities on vehicles. The computation of accumulators on CA is also low in the proposed scheme. Finally, we formally prove that the proposed scheme, which is based on q‐strong Diffie–Hellman, n‐Diffie–Hellman exponent (DHE), variant n‐DHE, and decision linear Diffie–Hellman assumptions, is secure under the definitions of traceability and anonymity.