Gateway-Oriented Password-Authenticated Key Exchange Based on Chameleon Hash Function

A gateway-oriented password-based authenticated key exchange (GPAKE) is a three-party protocol, which allows a client and a gateway to establish a common session key with the help of an authentication server. Besides the semantic security of the session key, the desirable security properties of a GPAKE protocol also include password protection with respect to malicious gateways and key privacy with respect to honest-but-curious authentication servers. Unfortunately, previous solutions are suspectable to undetectable on-line dictionary attacks by a malicious gateway. To overcome this shortcoming, we propose a GPAKE protocol based on chameleon hash function in this paper. By the merit of chameleon hash function, the authentication server can distinguish an honest authentication request by a client from an on-line impersonation attack by a malicious gateway. The proposed protocol is secure against undetectable on-line dictionary attacks. In addition, it is as efficient as previous solutions.