Decentralized and Scalable Privacy-Preserving Authentication Scheme in VANETs

Existing authentication schemes are based on either symmetric or asymmetric cryptography such as public-key infrastructure (PKI). These PKI-based authentication schemes are highly recommended to address the security challenges in VANETs. However, they have certain shortcomings such as: 1) lack of privacy-preservation due to revealing of vehicle identity and broadcasting of safety-message and 2) lengthy certificates leading to communication and computation overheads. The symmetric cryptography based schemes on the other hand are faster because they use a single secret key and are very simple; however, it does not ensure nonrepudiation. In this paper, we present a decentralized and scalable privacy-preserving authentication (DSPA) scheme for secure vehicular ad hoc networks. The proposed scheme employs a hybrid cryptography. In DSPA, the asymmetric identity-based (ID-based) cryptography and the symmetric hash message authentication code (HMAC) based authentication are adopted during vehicle to infrastructure and vehicle to vehicle communications, respectively. Extensive simulations are conducted to validate the proposed DSPA scheme by comparing the existing works based on PKI, ID-based, group signature, batch verification, and HMAC. The performance analysis showed that DSPA is more efficient, decentralized, scalable, and also a privacy-preserving secured scheme than the existing authentication schemes.