A Robust and E cient SIP Authentication Scheme

The Session Initiation Protocol (SIP), which is becoming the de facto standard for the next-generation VoIP networks, is currently receiving much attention in many aspects. One aspect that was not deeply addressed in the original SIP is its authentication procedure. Apart from its security, an SIP authentication procedure should be e cient. This paper proposes a robust and e cient three-party SIP authentication protocol. In this protocol, the end users are authenticated with the proxy server in their domain using the registrar server. Compared to previous works, our proposed protocol is more e cient and secure. To support our protocol with a formal security proof, its model is constructed using High-Level Protocol Speci cation Language (HLPSL). The model is veri ed using the model checking tool, AVISPA, and the result con rms that the protocol is quite safe.