UCL Discovery

Abstract

Given an arbiter whose arbitrage is trusted, an authentication scheme is presented which is unconditionally secure against impersonation and/or substitution attacks performed by the arbiter, whereas previous scheme did not protect against such attacks. Furthermore, the scheme protects unconditionally against: impersonation/substitution attacks done by an outsider, against disavowal of a message by the sender, and against the receiver forging a message which was never sent. A practical scheme based on finite geometry is presented. Adaptations of the scheme realize an asymmetric conventional authentication scheme, and the set-up of an unconditionally secure oblivious transfer system.