Cryptanalysis of Farash et al.'s SIP authentication protocol

Session initiation protocol (SIP) is the most popular signalling protocol used in order to establish, maintain and terminate a multimedia sessions between different participants. Nowadays, the security of SIP is becoming more and more important. Authentication is the most important security service required for SIP. To provide secure communication, many SIP authentication schemes have been proposed. Very recently, Farash et al. proposed a new SIP authentication protocol based on elliptic curve cryptography. They proved that their scheme is secured against different attacks. However, in this paper we show that Farash et al.'s protocol suffers from Denning-Sacco attacks and denial of service attacks. Moreover, we propose our solution to solve the problem. The security analysis shows that our proposed solution is more secure and can resist to various attacks.