A New Digital Signature Scheme without One-Way Hash Functions and Message Redundancy

In 2004, Chang et al. proposed a signature scheme without employing one-way hash functions and message redundancy schemes. Later, Zhang and Fu et al. presented the forgery attack on Chang's digital signature and claimed that message redundancy schemes should still be used to resist some attacks. In this letter, we will point out a fatal flaw of Chang's scheme and propose a new digital signature scheme, where neither one-way hash functions nor message redundancy schemes are used.