PTRS: A privacy-preserving trust-based relay selection scheme in VANETs

As one of the essential components of Intelligent Transport Systems (ITS), Vehicular Ad Hoc Network (VANET) plays a significant role in enabling various on-road applications, most of which primarily rely on two-hop Vehicle-to-Infrastructure communications. To make such communications reliable and secure, it is significant to ensure that only the trustworthy vehicles are selected as relays. To tackle this challenge, this paper proposes a robust trust-based relay selection scheme, called PTRS, which, based on Dirichlet distribution, systematically integrates a set of unique features of VANET, e.g., hybrid architecture, high dynamics, into the traditional reputation system, with an objective to effectively differentiate the trust levels of the vehicles, meanwhile, preserving robustness. Besides, the location privacy of vehicles are preserved in our proposed scheme by using the technique of pseudonyms and trust levels instead of explicit reputation scores. Detailed security analysis is conducted, which shows that the proposed PTRS scheme is secure and robust against several sophisticated attacks in VANETs. In addition, a set of extensive simulations are carried out, demonstrating its effectiveness and accuracy.