An Efficient Authentication Scheme Based on Semi-Trusted Authority in VANETs

With the development of intelligent transportation systems, vehicular ad hoc networks (VANETs) are widely used in safety driving, and so on. However, existing signature schemes, such as pseudonym- and group-based schemes, have certain problems, such as the need for a certificate distribution and certificate revocation lists (CRLs). With such schemes, the vehicle needs to store a valid certificate generated by the management center. Simultaneously, the receiver needs to check the CRLs prior to message authentication. CRLs require large amounts of storage space and computational and communication resources. In addition, many such schemes are built on a trusted authority and do not meet real-world needs. Thus, we propose an efficient authentication scheme based on semitrusted authority in VANETs. In this scheme, we combine the self-healing key distribution method with a certificateless signature in a semitrusted authority environment, such that the receivers do not require to query the CRLs. Therefore, the vehicles do not have to store the CRLs, thereby saving storage space and communication resources. This also reduces the computational costs and improves the efficiency of the message authentication. Since the proposed scheme is built on a semitrusted authority, it is a more realistic approach.