Message Authentication Scheme for Vehicular Ad-Hoc Wireless Networks without RSU

Studies were conducted on vehicular ad-hoc network (VANET) in recent years. VANET is a network that combines on-board wireless equipment (On-Board Unit, OBU) and roadside fixed wireless equipment (Road Side Unit, RSU) through wireless communication technology. When vehicles broadcast messages, the traditional systems usually use RSU to do message authentication that we can ensure messages are integrity (message authentication) and broadcasted by legitimate vehicles (identity verification). But the cover range of RSU is limit and the cost is expensive, so these systems cannot work without RSU. In this paper, we propose the mechanism based on chameleon hashing and HMAC to do identity verification and message authentication under the environment without RSU. In the proposed scheme, two secret values are retained by TA, and TA will use these secret values to create and pre-load a public identity and a secret value to every registered vehicle. Based on the public identity and the secret value, a vehicle can broadcast message and make secure communication with other vehicles. The other vehicles can also make the message authentication and identity verification based on the techniques of chameleon hash, HMAC and Diffie-Hellman key exchange. The security and performance analysis show that the proposed scheme is secure and its performance is more superior than the related works.