Masquerade on One-Time Password Authentication Scheme

In 2002, Yeh et al. proposed a one-time password authentication scheme using smart cards. Later, Tsuji et al. and Ku et al. respectively showed that Yeh et al.´s scheme is vulnerable to stolen-verifier attacks. Recently, Lee and Chen proposed an improvement of Yeh et al.´s scheme. Lee and Chen claimed that their improvement can effectively withstand the stolen-verifier attack and is as efficient as Yeh et al.´s scheme. This paper, however, will point out that Lee and Chen improvement is still vulnerable to a masquerade attack. And, a simple improvement is given to resist the masquerade attack.