Fail-Stop Confirmer Signatures

Abstract

A designated confirmer signature allows the signer to prove to the signature’s recipient that the designated confirmer can confirm the signature without the signer. In this paper we propose a fail-stop confirmer signature scheme based on the concept of fail-stop knowledge proofs and signature knowledge proofs on discrete logarithms. We also develop a blinded version of the confirmer scheme. The new confirmer signatures have enhanced security against forgery from powerful adversaries.