Flaws and Amendment in an ECC-based Authentication Scheme for SIP

In this paper, we study the pitfalls of Qiu et al.'s protocol proposed for session initiation protocol and also suggest amendment in it. We reveal that their protocol has a mistake in the mechanism of establishing the session key between the user and the server. Because of this, their protocol cannot achieve mutual authentication. The scheme also suffers from a replay attack. To recover these problems in their protocol, we propose an amended protocol to provide better security and achieve mutual authentication. The informal security analysis shows the superiority of the improved protocol over Qiu et al.'s protocol.