Ring Signature-Based Conditional Privacy-Preserving Authentication in VANETs

Vehicular ad hoc networks (VANETs) consist of vehicles with high mobility that broadcasts delay-intolerant safety and informative messages frequently. The real identity of a vehicle needs to be kept private as these vehicles operate in an open and insecure network. A receiving vehicle must also authenticate the received messages before accepting or rejecting it. Additionally, the original identity of an authenticated vehicle must be discovered if it tries to obstruct the normal functioning of the network by transmitting the wrong messages. In this paper, a lightweight ring signature-based conditional privacy-preserving authentication (RCPPA) scheme is proposed to address the security issues in VANETs. In the proposed scheme, a vehicle gets a pseudonym from root trusted authority (RTA). If a vehicle performs a malicious action, then only RTA can reveal the original identity of the vehicle. A vehicle produces a ring signature to sign a message. Vehicles within the communication range verify this signature to ensure that the message is sent from an authenticated vehicle. Ring signature provides unconditional privacy to vehicles, but a pseudonym that is sent in the message is used by the RTA to reveal the real identity. The biggest advantage of this scheme is that it allows only authenticated vehicles to generate a ring signature and not any intruder without requiring any cooperation from any other vehicle. The results of the simulation show that the RCPPA scheme using a ring signature and pseudonym provides not only vehicle and message authentication but also non-repudiation through conditional privacy-preservation.