A conditional privacy scheme based on anonymized batch authentication in Vehicular Ad Hoc Networks

Addressing security and privacy issues is a prerequisite for market-ready Vehicular Ad Hoc Networks. In this paper, an anonymous batch authentication scheme is proposed to authenticate multiple requests sent from different vehicles at the same time. The scheme achieves privacy-preserving by pseudonyms, ensures the backward privacy of the revoked vehicles by hash chain, and realize the batch authentication by using an identity-based signature (IBS). To avoid the communication overhead caused by broadcasting the Certificate Revocation List (CRL) and the privacy disclosure issue of the revocation vehicles, we revoke the illegal vehicles through calculating Hash Message Authentication Code (HMAC) by using the group key. In addition, integrity of the batch messages is ensured and efficient batch authentication is achieved. The analysis shows that our scheme has a better performance than the current batch authentication schemes on authentication delay and revocation overhead. The generated group key and pair key during the authenticated process can be used for value-added service, as the realization of HMAC doesn´t require additional overhead.