An improved efficient remote password authentication scheme with smart card over insecure networks,”

's scheme and both of them pointed out, more or less, same vulnerabilities: like offline password guessing attack, impersonating the server by replay attack, denial of service attack on password changing and insider attack on it. But none of them suggested any solution to the pointed out attacks. This paper proposes an improved scheme with enhanced security, maintaining advantages of the original scheme and free from the attacks pointed out by Yoon-Yoo and Xiang et al.