Some more Improvements on a fair non-repudiation protocol

Abstract

This paper examines the Zhou-Gollmann fair non-repudiation protocol as well as its modified version of Kim et al. We describe how these protocols are vulnerable to an attack by a misbehaving originator which may degrade the efficiency or even cause denial of the non-repudiation service and propose a modification which prevents this attack. Furthermore, we propose a variant which achieves semantically secure message confidentiality without increasing key management costs.