More Efficient and Secure Remote User Authentication Scheme using Smart Cards

In 2004, Lee et al. proposed an improvement to Chien et al´s scheme to prevent parallel session attack and in which any legal users could choose and change their passwords freely. This paper, however, demonstrates that Lee et al.´s scheme is vulnerable to masquerading server attack. Additionally, we point out to the system´s secret key forward secrecy problem and insecure password change. Furthermore, the current paper presents a more efficient and secure scheme in that it not only resolves such problems but also involves less computations and communications than Lee et al.´s scheme