Threshold signature is designed to distribute the power of signature

therefore it is more secure than normal single signature.Most of the existing threshold signatrue schemes are provable secure in the random oracle model.An identity-based signature (IBS) is proposed from the bilinear parings based on Paterson's signature scheme In the proposed threshold signatue scheme

a trusted private key generator (PKG) is required to generate and manage the private secret key.The security of the signature scheme is proven in this paper.We show that it is strong and resisted against adapt chosen message attack.