A Privacy-Preserving Mutual Authentication Resisting DoS Attacks in VANETs.

Providing efficient anonymous authentication in vehicular ad hoc networks (VANETs) is a challenging issue. Identity-based signature schemes have been used to provide privacy-preserving authentication effectively for VANETs. In such scenario, mutual authentication between vehicles is critical to ensure only legitimate vehicles can involve in the inter-vehicle communication, and how to resist denial-of service attack should be carefully addressed due to the regionally central signature verification in vehicle roadside communications. In this paper, we propose a conditional privacy-preserving mutual authentication framework with denial-of-service attack resistance called MADAR. The authentication framework combines different identity-based signature schemes and distinguishes inner-region and cross-region authentications to increase efficiency. Beyond the privacy preservation and non-repudiation achieved by the existing framework, our authentication framework provides asymmetric inter-vehicle mutual authentication and strength-alterable computational DoS-attack resistance. We have formally proved the privacy preservation, unlinkability, mutual authenticity, and correctness of pseudonym with ProVerif, and analyzed other security objectives. The performance evaluations are conducted and the results demonstrate that our framework can achieve these security objectives with moderate computation and communication overheads.