A Four-Party Password-Based Authentication Key Exchange Protocol

In this paper, we propose a four-party password-based authentication key exchange protocol, in which it has three clients A, B, and C, and a trusted server-side participant S. in the protocol, each client shares a password with the server and resorts to the server to authenticate the peer for establishing a session key. Our protocol is based on the chosen-based computation Diffie-Hellman assumption, and it only needs two rounds between the clients and the server. by security analysis, we show that our protocol can resist the dictionary attacks, the impersonation and man-in-the-middle attacks.