Outline of Paper. Sections 2 and 3 present the communications model and definitions of security which we use. These follow quite closely the definitions of Xxxxxxx and Rog- away [4] with modifications required for the special situation of conference keys. Section 4 presents our new protocol and explains the differences from other re- lated protocols. Section 5 presents the proof of security. 2 Communications Model We follow closely the model established by Xxxxxxx and Rogaway [7, 4] incorpo- rating later updates [6]. In particular we use the later form of partnering which seems more suitable for the multi-party environment. A U G { }
Outline of Paper. Section 2 presents some background information on the SIP standard, RFC3261, and how authentication and key agreement are currently performed. In Section 3, ID-based cryptography is briefly introduced, followed by a presentation of the improved provably secure protocol 3 of Xxxx & Xxxxx [7], which the new SIP key agreement protocol utilises. In Section 4 the new SIP authentication mechanism and key agreement protocol is shown. This is followed by a discussion of the proposed solution and observed limitations in Section 5. Finally, Section 6 concludes with an exploration of possible avenues for future work.
Outline of Paper. Section 2 presents some background information about SIP authentication scheme, RFC3310. In section 3, the new SIP key agreement protocol is shown. The security proof is given in section 4. This is followed by a discussion of the proposed solution and observed limitations in Section 5. Finally, Section 6 concludes the paper. 2 SIP Authentication Procedure SIP authentication [2] security is based on the challenge-response mechanism, in which a nonce value is used in challenging the target. Before the scheme starts, the client pre-shares a password with the server. SIP applies the digest mechanism for authenticating users to users or users to proxies, not proxies to proxies. The security between proxies relies on other mechanisms, for example TLS or IPsec. Figure 1 is an example flow of authentication mechanism in SIP.
Outline of Paper. The next section contains formal descriptions of our model, the allowed interac- tive communication, and a SK, along with a definition of the SK capacity. Also, we review some basic notions in binary hypothesis testing that will be used in this paper. Our main result is Theorem 1 in Section 3; implications of this main result are presented as corollaries. In Section 4, we show that our new upper bound is asymptotically tight and leads to a strong converse for the SK capac- ity. Implications for the secure computing problem with trusted parties, along with illustrative examples, are given in Section 5. The final section contains a discussion of our results.
