Cryptanalysis on Chang-Yang-Hwang Protected Password Change Protocol.
Chih-I Wang, Chun‐I Fan, D.J. Guan · IACR Cryptology ePrint Archive · 2005
Recently, Chang et al. proposed an authenticated key agreement and protectedpassword change scheme. They claimed that their scheme is simple and ecient.However, in this letter we point out that their protected password change pro-tocol is insecure under the denial-of-service attack and the dictionary attack insome situations.Keywords: Authentication, Passwords, Information security, Cryptography.1 Introduction: Ubiquitous communication networks connect lots of distributedentities together such that they can exchange and share large amounts of infor-mation and resources. In order to guarantee security, it is necessary for any twodistributed entities to mutually verify the identity of each other before they setup a new connection. User authentication is one of the most important security