Improved Remote User Authentication Scheme Preserving User Anonymity

Most of smart card-based remote authentication schemes proposed didn ´t protect the users´ identities while authenticating the users, even though user anonymity is an important issue in many e-commerce applications. In 2004, Das et al. proposed a remote authentication scheme to authenticate users while preserving the users´ anonymity. Their scheme adopted dynamic identification to achieve this function. Then in 2005, Chien and Chen pointed out Das et al. ´s scheme fails to protect the user´s anonymity and proposed a new remote authentication scheme preserving user anonymity. This paper, however, will demonstrate that Chien and Chen´s scheme has also some problems: it cannot resist strong masquerading server/user attack, insider attack, denial of service attack and restricted replay attack; it also has the problem of slow wrong password detection. Therefore, an improved scheme is proposed to conquer these problems.