A Tight Security Reduction Identity-Based Signature Scheme

In ACISP 2006, Paterson and Schuldt(PS) presented an efficient identity-based signature scheme in the standard model. Their scheme is obtained from a modification of Waters´ identity-based encryption scheme. It employed two Waters Hash functions, one for identity, other for message, so the security reduction efficiency is very low. We slightly modify PS´s scheme and change the parameters selection in security proof to obtain a tight security reduction identity- based signature scheme. The new scheme´s security rests on computational Diffie-Hellman assumption.