A Secure and Efficient Authentication Technique for Vehicular Ad-Hoc Networks

Vehicular ad-hoc networks (VANETs) have been emerging due to the recent technologies in wireless and network communications. The most fundamental part in VANETs is to enable message authentications between vehicles and roadside units. Message authentication using proxy vehicles has been proposed to reduce the computational overhead of roadside units significantly. In this type of message authentication schemes, proxy vehicles with verifying multiple messages at the same time improve computational efficiency of roadside units when there are a large number of vehicles in their coverage areas. In this paper, first we show that the only proxy-based authentication scheme (PBAS) presented for this goal by Liu et al. cannot achieve authenticity of messages, and also it is not resistant against impersonation and modification attacks and false acceptance of batching invalid signatures. Next, we propose a new identitybased message authentication using proxy vehicles (ID-MAP). Then, to guarantee that it can satisfy message authentication requirement, existential unforgeability of underlying signature against adaptively chosen-message and identity attack is proved under Elliptic Curve Discrete Logarithm Problem in the random oracle model. It should be highlighted that ID-MAP not only is more efficient than PBAS since it is pairing-free and does not use map-to-point hash functions, but also it satisfies security and privacy requirements of vehicular ad hoc networks. Furthermore, analysis shows that the required time to verify 3000 messages in ID-MAP is reduced by 76% compared to that of PBAS.