Enhancing Security and Privacy for Identity-based Batch Verification Scheme in VANET Vehicular ad hoc network (VANET) can significantly improve the traffic safety and efficiency. The basic idea is to allow vehicles to send traffic information to roadside units (RSUs) or other vehicles. Vehicles have to be prevented from some attacks on their privacy and misuse of their private data. For this reason, the security and privacy preservation issues are important prerequisites for VANET. The identity-based batch verification (IBV) scheme was newly proposed to make VANET more secure and efficient for practical use. In this paper, we point out that the current IBV scheme exists some security risks. We introduce an improved scheme that can satisfy the security and privacy desired by vehicles. The proposed IBV scheme provides the provable security in the random oracle model. In addition, the batch verification of the proposed scheme needs only a small constant number of pairing and point multiplication computations, independent of the number of messages. We show the efficiency merits of the proposed scheme through performance evaluations in terms of computation delay and transmission overhead. Moreover, the extensive simulation is conducted to verify the efficiency and applicability of the proposed scheme in the real-world road environment and vehicular traffic.