Enhancements of a three-party password-based authenticated key exchange protocol

This paper discuss the security for a simple and efficient three-party password-based authenticated key exchange protocol proposed by Huang most recently. Our analysis shows her protocol is still vulnerable to three kinds of attacks : (1) undetectable on-line dictionary attacks ; and (2) key-compromise impersonation attack. Thereafter we propose an enhanced protocol that can defeat the attacks described and yet is reasonably efficient.