Provably secure authenticated key exchange protocol under the CDH assumption

Constructing a secure key exchange protocol is one of the most challenging problems in information security. We propose a provably secure two-round two-party authenticated key exchange (2AKE) protocol based on the well-studied CDH assumption in eCK model to provide the strongest definition of security for key exchange protocol when using the matching session to define the partnership. The underlying hardness assumption (CDH assumption) of our protocol is weaker than these of four other provably secure 2AKE protocols in CK model or eCK model and the computational cost of our protocol is reasonable. We also present a three-round variant of our protocol to realize key conformation.