Designing a secure authentication scheme for session initial protocol (SIP) over internet protocol (VoIP) networks remains challenging. In this paper, we revisit the protocol of Zhang, Tang and Zhu (2015) and reveal that the protocol is vulnerable to key-compromise impersonation attacks. We then propose a SIP authenticated key agreement protocol (AKAP) using elliptic curve cryptography (ECC). We demonstrate the correctness of the protocol using Burrows-Abadi-Needham (BAN), and its security using the AVISPA simulation tool. We also evaluate its performance against those of Zhang, Tang and Zhu, and others.
Keywords: authentication; elliptic curve cryptography; privacy; security; session initial protocol.