Faults and Improvements of an Enhanced Remote User Authentication Scheme Using Smart Cards

In 2000, Hwang and Li proposed a remote user authentication scheme using smart cards to solve the problems of Lamport scheme. Later, Chan- Chang, Shen- Lin- Hwang and then Chang-Hwang pointed out some attacks on Hwang – Li’s scheme. In 2003, Shen, Lin and Hwang also proposed a modified scheme to remove these attacks. In the same year, Leung-Cheng-Fong-Chan showed that modified scheme proposed by Shen-Lin-Hwang is still insecure. In 2004, Awasthi and Lal enhanced Shen-Lin-Hwang’s scheme to overcome its security pitfalls. This paper analyses that the user U/smart card does not provide complete information for the execution and proper running of the login phase of the Awasthi- Lal’s scheme. Furthermore, this paper also modifies the Awasthi- Lal’s scheme for the proper functioning.