Abstract
Key exchange protocol is important for sending secret messages using the session key between two parties. In order to reach the objective, the premise is to generate a session key securely. Encryption key exchange was first proposed to generate a session key with a weak authenticated password against guessing attacks. Next, another authenticated key exchange protocols for three-party, two clients who request the session key and one server who authenticates the user’s identity and assists in generating a session key, were proposed. Once the clients are under diverse circumstances, they have to be authenticate by their own server. That is, it needs four-party to complete this protocol. In this paper, we focus on the four-party authenticated key exchange protocol, and presents four-party EKE.