An efficient three-factor privacy-preserving authentication and key agreement protocol for vehicular ad-hoc network

As an indispensable part of the Intelligent Transportation System (ITS), the vehicular adhoc network (VANET) has attracted widespread attention from academia and industry. In order to ensure the security of VANET, vehicles need to be authenticated before accessing the network. Most existing authentication protocols in VANET adopt the Trusted Authority (TA) with centralized structure which is responsible for the authentication tasks of all vehicles. However, the large-scale network consume a lot of computing resources, which leads to unacceptable delay in message transmission in VANET. For reducing the computational cost of TA, an efficient three-factor privacy-preserving authentication and key agreement protocol was proposed in our paper. Different from before, the RoadSide Unit (RSU) no longer acts as an intermediate node but is responsible for assisting user authentication, which lead to the computational cost of TA is very low. Through formal and informal analysis, our protocol demonstrates excellent security. Compared with previous studies, our work emerges advantages and superiorities in the following aspects: computational cost, communication cost, security properties and functions, message loss ratio, and message delay. These data and evidence indicate that our protocol is an ideal choice for large-scale VANET.