Identity-based(ID-based)ring signature has drawn great concerns in recent years and many ID-based ring signature schemes have been proposed until now.Unfortunately,all of these ID-based ring sig-natures are constructed from bilinear pairings,a powerful but computationally expensive primitive.Hence,ID-based ring signature without pairing is of great interest in the field of cryptography.In this pa-per,the authors firstly propose an ID-based ring signature scheme based on quadratic residues.The pro-posed scheme is proved to be existentially unforgeable againsi adaptive chosen message-and-identity attackunder the random oracle model,assuming the hardness of factoring.The proposed scheme is more effi-cient than those which are constructed from bilinear pairings.
