A Distributed Model for Privacy Preserving V2I Communication with Strong Unframeability and Efficient Revocation

Abstract

Although Vehicle to Infrastructure (V2I) communications greatly improve the efficiency of early warning systems for car safety, communication privacy is an important concern. Although solutions exist in the literature for privacy preserving VANET communications, they usually require high trust assumptions for a single authority. In this paper we propose a distributed trust model for privacy preserving V2I communications. Trust is distributed among a certification authority that issues the vehicles’ credentials, and a signing authority that anonymously authenticates V2I messages in a zero knowledge manner. Anonymity is based on bilinear pairings and partially blind signatures. In addition, our system supports enhanced conditional privacy since both authorities and the relevant RSU need to collaborate to trace a message back to a vehicle, while efficient certificateless revocation is supported. Moreover, our scheme provides strong unframeability for honest vehicles. Even if all the entities collude, it is not possible to frame a honest vehicle, by tracing a forged message back to an honest vehicle. The proposed scheme concurrently achieves conditional privacy and strong unframeabilty for vehicles, without assuming a fully trusted authority. Our evaluation results show that the system allows RSUs to efficiently handle multiple messages per second, which suffices for real world implementations.