Secure Verifier-Based Three-Party Key Exchange in the Random Oracle Model

A Three Party password Authenticated Key Exchange protocol (3PAKE) facilitates two clients to establish authenticated session keys via the help of a trusted server. This approach enhances the scalability of key agreement issue and facilitates users’ convenience in distributed environments. In this paper, we show the security weaknesses of previous works, and then propose our new scheme, using password verifiers. The scheme is efficient, and the key indistinguishability is proved relative to the computational Diffie-Hellman problem. It is the first provably secure verifier-based 3PAKE protocol.