Further improvement on the modified authenticated key agreement scheme

摘要

In 2003, Hsu et al. showed that the Ku-Wang modified authentication key agreement scheme is vulnerable to the modification attack and further proposed an improvement of the Ku-Wang scheme. However, we find that the Hsu et al. scheme still suffers from the same modification attack. This paper will first show the security flaw in the Hsu et al. scheme, and then propose an improved scheme to repair the security flaw.