Cryptanalysis on Sun-Yen's Password-Based Authentication and Key Distribution Protocols with Perfect Forward Secrecy

摘要

Recently, Sun and Yeh proposed three password-based authentication and key distribution protocols with perfect forward secrecy with low, medium, and high security, respectively, in the environment of three principals involved: a client, an application server, and an authentication server. In this paper, we will show that each of their protocols has some security flaw; the protocol with low security is vulnerable to the known-plaintext attack and the other two are subject to the man-in-the-middle attack.