Efficient password-based authentication and key exchange scheme preserving user privacy

With the flourish of applications over the wired /wireless networks, how to keep user's privacy has drawn growing concerns in recent years. Although the issue of user anonymity has been addressed in digital signature field by introducing the concepts of ring and group signatures, they are not suitable to anonymously authenticate a user in wireless mobile applications, because these signature schemes need infrastructure support and heavy computational costs which is beyond the computational ability of a smart card embedded in a hand-held device. In this paper, we propose an anonymous authentication scheme which also supports Diffie-Hellman key exchange. Our scheme is very efficient since it mainly uses hash and XOR operations. Moreover, our scheme possesses many good virtues of existing authentication schemes.