Provably Authenticated Group Diie-hellman Key Exchange

Group Diie-Hellman protocols for Authenticated Key Exchange (AKE) are designed to provide a pool of players with a shared secret key which may later be used, for example, to achieve multicast message integrity. Over the years, several schemes have been ooered. However, no formal treatment for this cryptographic problem has ever been suggested. In this paper, we present a security model for this problem and use it to precisely deene AKE (with \implicit" authentication) as the fundamental goal, and the entity-authentication goal as well. We then deene in this model the execution of an authenticated group Diie-Hellman scheme and prove its security.