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, will demonstrate that Lee et al.’s scheme is vulnerable to masquerading server attack. Additionally, we will 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.