Practical Password-Authenticated Three-Party Key Exchange
Jeong Ok Kwon · KSII Transactions on Internet and Information Systems · 2008
Password-based authentication key exchange (PAKE) protocols in the literature typically assume a password that is shared between a client and a server.PAKE has been applied in various environments, especially in the "client-server" applications of remotely accessed systems, such as e-banking.With the rapid developments in modern communication environments, such as ad-hoc networks and ubiquitous computing, it is customary to construct a secure peer-to-peer channel, which is quite a different paradigm from existing paradigms.In such a peer-to-peer channel, it would be much more common for users to not share a password with others.In this paper, we consider password-based authentication key exchange in the three-party setting, where two users do not share a password between themselves but only with one server.The users make a session-key by using their different passwords with the help of the server.We propose an efficient password-based authentication key exchange protocol with different passwords that achieves forward secrecy in the standard model.The protocol requires parties to only memorize human-memorable passwords; all other information that is necessary to run the protocol is made public.The protocol is also light-weighted, i.e., it requires only three rounds and four modular exponentiations per user.In fact, this amount of computation and the number of rounds are comparable to the most efficient password-based authentication key exchange protocol in the random-oracle model.The dispensation of random oracles in the protocol does not require the security of any expensive signature schemes or zero-knowlegde proofs.