Abstract: This paper presents an efficient anonymous message authentication scheme for vehicular ad hoc networks. By using identity-based sign-encryption technique, a vehicular user can first authenticate with a region center to obtain a group signature key material, where the group is managed by the region center. Then, the user can employ the key material to sign a message and broadcast it into the network. Other vehicular users can directly check the signature without revocation verification. In addition, the used group signature supports batch verification, which significantly reduces the verification overhead. Compared with the existing schemes, the proposed scheme can achieve backward secure revocation.