A Pairing-Free Identity-Based Authenticated Key Agreement Mechanism for SIP

The session initiation protocol (SIP) is widely used as a signaling protocol based on the challenge-response exchange mode for handling multimedia sessions in both wire line and wireless world. The original authentication mechanism of SIP is HTTP digest based authentication, which is vulnerable to many forms of known attacks and therefore can not provide security at an acceptable level. In this paper, we propose an identity-based authenticated key agreement mechanism which can be used in SIP to solve the security problems existing in its original authentication procedure. The proposed scheme uses Elliptic Curve Cryptography and does not require expensive bilinear pairing operations, which makes it computationally much more efficient than previous identity-based and Certificateless schemes using pairings. We show the security of our proposal under the Canetti-Krawczky model. Our scheme captures many desirable security properties and can prevent various possible attacks induced by open networks and the standard of SIP message. Furthermore, through introducing some design ideas from Certificateless cryptography, our proposal avoids not only the requirement of a large Public Key Infrastructure but also key escrow problem.