Password-based Group Key Exchange Protocol

Password-based group key agreement protocol is developing with the security requirements in Ad Hoc.This protocol allows a group of users,who share a human-memorable low entropy password, and communicating over a public network, to agree upon a high entropy session key among themselves.This session key can later be used to implement secure multi-cast sessions.One function of password is it can be used as a sharable message which can authenticate the key of migration nodes;another function is it can be used as symmetric key which can encrypt the communicational messages among the migration nodes.To overcome other protocol's shortcomings ,we propose three new protocols.The new protocols are very efficient and fully scalable,since they only require constant rounds of communication.We give them the analyse security and focus on fist two protocol which are given provably secure under the standard model.