A scalable and efficient PKI based authentication protocol for VANETs

Intelligent Transportation System (ITS) has came up as important solution for safety of automotive users. ITS deployment in near future will not only improve drivers and passengers safety but also will reduce road safety and traffic congestion problems by providing information to its users. The vehicles will be capable of communicating with other vehicles as well as with road side infrastructure to form self-organizing vehicular ad hoc networks (VANETs). VANETs as core part of ITS enables transfer of data among the entities of ITS. This data consists of private information of VANETs users such as exact location. Therefore, authentication of users is mandatory to restrict access of this information by any malicious user or attacker. PKI based authentication is considered as a feasible scheme for VANETs. However, enormously sized Certificate Revocation List (CRL) adds extra delay in process of authenticating requests. This makes users unable to acquire services timely and obstructs the scalability of VANETs. In this paper, we propose a protocol which makes CRL size linear and authentication process efficient. We perform simulations to show the reduced authentication delay for wide range of authentication requests.