A Differentiated Identity Authentication Protocol for VANETs Based on Safety Level

In Vehicular Ad Hoc Networks (VANETs), authentication is a crucial security service for both inter-vehicle and vehicle-roadside unit communications. Most of traditional protocols do not consider the impact of vehicular safety on authentication efficiency, thus implementing the same authentication process for all vehicles, which leads to large overhead and inflexible authentication. In this paper, we propose a differentiated identity authentication protocol based on vehicular safety level to reduce the authentication overhead and increase flexibility. In the proposed protocol, Roadside Unit (RSU) can choose appropriate authentication method for vehicle according to its safety level, which is evaluated by hardware safety and behavior safety. In addition, anonymous mutual authentication with key agreement is enabled by exploiting the trapdoor collision property of chameleon hash functions, thus the proposed protocol can effectively avoid the communication overhead caused by the transmission of certificates, and there is no key escrow problem. At the same time, combined with Physical Unclonable Functions (PUFs) technology, the proposed protocol can resist physical attacks. Simulation results demonstrate that the proposed protocol can not only effectively improve the flexibility of vehicular authentication, but also have advantages in reducing computation delay and communication overhead.