Reliable Cooperative Authentication for Vehicular Networks

Vehicular ad-hoc networks (VANETs) have been researched with regard to enhance driver's safety and comfort. In VANETs, all vehicles share their status and road conditions with neighboring nodes by periodically generating safety messages. To provide reliable VANET services, message authentication is an important feature. In particular, anonymous message authentication has attracted considerable interest, because periodic broadcast messages from a vehicle can be used to track its location. Unfortunately, previously proposed anonymous message authentication protocols had serious practical shortcomings, including high communication, authentication, and revocation costs, as well as reliability issues. Thus, in this paper, we propose an anonymous authentication protocol based on a cooperative authentication method. The proposed method does not require mode synchronization between cooperative and non-cooperative authentication. In addition, we design a two-layer pseudo-identity generation method and construct a key update tree for efficient revocation. Simulations show that our protocol does not result in packet losses caused by authentication overheads, even when the vehicle density is 200/km².