Improvement of Chien et al.'s remote user authentication scheme using smart cards

In 2000, Sun proposed an efficient remote user authentication scheme using smart cards. Later, Chien et al. pointed out that Sun's scheme does not provide the mutual authentication between the user and the server and allow users to freely choose password themselves. Chien et al. further proposed a new efficient and practical solution to solve the problems. However, Hsu showed that Chien et al.'s scheme is vulnerable to the parallel session attack. This paper proposes an improved scheme to overcome the weakness while maintaining the advantages of Chien et al.'s scheme. (C) 2004 Elsevier B.V. All rights reserved.