Secure Multiround Authentication Protocols

Abstract

. Gemmell and Naor proposed a new protocol for unconditionally secure authentication of long messages. However Gehrmann showed that the proof of the security of the protocol was incorrect. Here we generalize the multiround protocol model. We prove the security of a 3-round protocol and give for this case a new easy implementable construction which has a key size close to the fundamental lower bound for even extremely long messages. Furthermore, we give a proof of a secure multiround protocol for an arbitrary number of rounds.