Efficient password-based authenticated key agreement protocol

In this paper, we present a new password-based authenticated key agreement protocol called PAKA, which provides mutual authentication and key agreement over an insecure channel between two parties knowing only a small password having low entropy. We then extend PAKA to a protocol called PAKA-X, in which the client uses a plaintext version of the password, while the server stores a verifier for the password, and which does not allow an adversary who compromises the server to impersonate a client without actually running a dictionary attack on the password file. The proposed protocols are secure against passive and active attacks and provide perfect forward secrecy.