Towards the Optimization of a Ticket-based Authentication Scheme for VANETs

Vehicular Ad hoc NETworks (VANETs) mainly intend to increase road safety by exchanging safety related messages. In order to provide a secure communication in VANETs, a key requirement is to enable receivers to authenticate received messages while preserving the privacy of the identities of sending vehicles. However, if a misbehavior takes place, involved vehicles should be identified and evicted from the network. To this end, we proposed in a previous work [1] a ticket-based authentication scheme for VANETs preserving privacy, in which vehicles use temporary tickets to communicate with other vehicles in the network while conditionally maintaining their privacy. A vehicle’s ticket is formed through two stages: an offline stage and an online stage. Besides, the ticket should be updated whenever its vehicle enters into a new domain (containing few Road Side Units), and modified whenever its validity period expires. In this paper, we propose an optimization of that previously proposed work in order to decrease the cryptographic delay. In fact, the Identity Based Online/Offline Signature (IBOOS) technique and Shamir’s trick are introduced, already verified tickets are stored by receiving vehicles for reference later and the signature size is reduced.