Known Session Keys. The Reveal query is designed to capture the notion that an adversary may learn previous session keys — in the model of distributed computing adopted, E may learn previous session keys by simply asking for them. The security definitions we have given for the AK and AKC problems demand that no adversary be able to learn any information about the session key held by a fresh oracle even when the adversary employs its Reveal query to learn other session keys. Any protocol for either AK or AKC which is secure under the definitions given will therefore resist known session key attacks.
