Abstract:

In the standard model an unforgeable chosen message attacks security  IBS(Identity-Based Signature)  scheme was proposed by PS(Paterson and Schuldt),
which was based on computational Diffie-Hellman problem in bilinear pairing group.Two independent Waters' identity hash functions were directly employed to tr
eat the user's identity and the signature message respectively,so PS's IBS scheme had poor security reduction efficiency.An improved Waters' identity hash function parameters selecting method was proposed.The new method was employed to improve PS's IBS signature scheme,which made the security reduction efficiency of the new IBS scheme having greatly improvementfrom O((q_kn)^-2) to O((q_kn)^-1),so the improved scheme was more security and trustable.

Key words: identity-based signature, standard model, security reduction efficiency