Certificateless authenticated two-party key agreement Protocols

In their seminal paper on certificateless public key cryptography, Al-Riyami and Paterson (AP) proposed a certificateless authenticated key agreement protocol. Key agreement protocols are one of the fundamental primitives of cryptography, and allow users to establish session keys securely in the presence of an active adversary. AP's protocol essentially requires each party to compute four bilinear pairings. Such operations can be computationally expensive, and should therefore be used moderately in key agreement. In this paper, we propose a new certificateless authenticated two-party key agreement protocol that only requires each party to compute two pairings. We analyze the security of the protocol and show that it achieves the desired security attributes. Furthermore, we show that our protocol can be used to establish keys between users of different key generation centers.