Weakness of Zhang-Wang Scheme Without Using One-Way Hash Function

摘要

Zhang and Wang proposed a signature scheme without using one-way hash function and message redundancy. It based on Chang-Chang scheme and gives an improvement which overcomes the known forgery attack. In this paper, we show this scheme can not suffer forgery attack where it does not use the one-way hash function. We believe the one-way hash function still demands message recovery and redundancy.