Identity-based signature scheme based on quadratic residues

Identity-based(ID-based)cryptography has drawn great concerns in recent years,and most of ID-based schemes are constructed from bilinear parings.Therefore,ID-based scheme without pairing is of great interest in the field of cryptography.Up to now, there still remains a challenge to construct ID-based signature scheme from quadratic residues.Thus,we aim to meet this challenge by proposing a concrete scheme.In this paper,we first introduce the technique of how to calculate a 2lth root of a quadratic residue,and then give a concrete ID-based signature scheme using such technique. We also prove that our scheme is chosen message and ID secure in the random oracle model,assuming the hardness of factoring.