Security enhancement and modular treatment towards authenticated key exchange

Abstract

We present an enhanced security model for the authenticated key exchange (AKE) protocols to capture the pre-master secret replication attack and to avoid the controversial random oracle assumption in the security proof. Our model treats the AKE protocol as two relatively independent modules, the secret exchange module and the key derivation module, and formalizes the adversarial capabilities and security properties for each of these modules. We prove that the proposed security model is stronger than the extended Canetti-Krawczyk model. Moreover, we introduce NACS, a two-pass AKE protocol which is secure in the enhanced model. NACS is practical and efficient, since it reqires less exponentiations, and, more important, admits a tight security reduction with weaker standard cryptographic assumptions. Finally, the compact and elegant security proof of NACS shows that our method is reasonable and effective. © 2010 Springer-Verlag.