A comprehensive survey on authentication and privacy-preserving schemes in VANETs

Abstract

Vehicular ad hoc networks (VANETs) promise to enhance transport efficiency, passenger safety, and comfort through the exchange of traffic and infotainment information to vehicles. The acceptance of VANET hinges on the correctness and timeliness of messages and assurance of an individual’s safety through privacy protection. The message accuracy requires the authentication of vehicles. This translates into the requirement of an efficient privacy-preserving authentication mechanism along with the need for privacy and time-bound delivery of messages. The security and privacy issues must be addressed primarily in the communication protocol’s design. Different privacy-preserving authentication schemes have been proposed to ensure the correctness of messages during vehicular communications. However, most of the schemes do not entirely solve the issues related to security and privacy, threats and vulnerabilities, communication, and computation costs. In this survey, we focus on cryptographic techniques proposed to achieve authentication, privacy, and other security features required in VANETs like symmetric key cryptography-based schemes, public key cryptography-based schemes, identity-based cryptography schemes, pseudonym-based schemes, group and ring signature-based schemes, and blockchain-based schemes. We provide a comprehensive study of schemes with their classifications, strengths, and weaknesses. The study reveals that most of the existing authentication schemes require trusted authorities that are opaque in their functioning, certificate revocation requires heavy computation and storage along with a large amount of lookup time. The computation and communication overhead required for authentication is significant, which drastically affects the timely delivery of messages. More work is needed for the development of lightweight and efficient privacy-preserving authentication schemes in VANETs.