This paper proposes an efficient Identity-Based authenticated key agreement protocol based on Waters’ Identity-Based Encryption scheme and gives a detail security analysis with provable security techniques in the standard model. It is more efficient than other similar protocols, and provides known-key security and forward secrecy. And it also resists key-compromise impersonation and unknown key share attacks. Moreover, this protocol is extended to satisfy the requirement that the session key should be escrowed by the Private Key Generation (PKG) center, and is given a key confirmation property with a secure message authentication code algorithm.