Password-Authenticated Key Exchange for Multi-Party with Different Passwords Using a Constant Number of Rounds

摘要

Multi-party password-authenticated key exchange (PAKE) with different passwords allows the users of a group to agree on a common session key with their different passwords by the help of a server. In this setting, a user shares a password only with the server, but not between the users. In this paper, we present two multi-party PAKE protocols. The suggested protocols are provably-secure in the standard model. Our first protocol is designed to provide forward secrecy and security against known-key attacks. The second protocol is designed to additionally provide key secrecy against the server which means that even the server can not know the session keys of the users of a group. The suggested protocols require a constant mimber of rounds.