An Improved Anonymous Password Authentication Scheme Using Nonce and Bilinear Pairings

In 2013, Li et al. pointed out the security problems of Chen’s password authentication scheme. they proposed an enhanced smart card based remote user password authentication scheme and claimed their scheme is secure against replay attacks, forgery attacks. In this paper, we state that the scheme is vulnerable to user impersonation attack. It also suffers from user anonymity violation and clock synchronization problem. Furthermore, an improved anonymity enhancement password authentication scheme using nonce and bilinear pairing is proposed. The analysis shows that the proposed scheme is more suitable for applications with high security requirements.