Cryptanalysis of a Chaotic Chebyshev Polynomials Based Remote User Authentication Scheme

In modern internet environments, the remote authentication scheme ensures a secure communication between a user and a server, hence its importance is significantly increasing. Numerous chaotic map based authentication schemes have been proposed to enable communication parties share session keys in a more secure manner. Recently, Truong et al. applied Chebyshev polynomials to propose an enhanced key agreement protocol and claimed that their scheme achieves many security requirements and could withstand various attacks. However, in this paper, we demonstrate that the scheme by Truong et al. is vulnerable to stolen smart card attack, session key derived attack and denial of service attack. Besides, a malicious user can launch identity guessing attack and impersonate any legal users and establish communication with the server.