Forward secrecy for an efficient password-based authenticated key exchange

A password-based authenticated key exchange (PAKE) protocol in the three-party setting allows two clients communicating over a public network to agree on a common session key with the help of a server In the setting the users do not share a password between themselves, but only with the server In this paper we propose a new efficient password-based authenticated three-party key exchange protocol and provide a rigorous conclusion of forward security for it in both the random-oracle and the ideal-cipher models under the gap Diffie-Hellman intractability assumption. It is a significant advantage that our protocol is proved secure in a model that allows the adversary to make adaptive corrupt queries, in contrast to previous solutions.