An Improved Timestamp-Based User Authentication Scheme with Smart Card

One of technologies to guarantee that only the legal users can access resources from the remote server is user authentication scheme. Many user authentication schemes are based on the use of smart card to withstand replay attack and password guessing attacks in last decades. Recently, Huang et al. proposed a timestamp-based user authentication with smart card. Their scheme is more secure and efficient than other schemes. However, we find the security of their scheme is also existed. In this article, we will prove their scheme is vulnerable to the password guessing attack. Finally, we will propose an improved scheme to eliminate the security vulnerability. Furthermore, the improved scheme could be used in the multi-server environments.