[1] Shamir A .Identity based cryptosystems and signature schemes .In :Proceedings of Crypto84 on Advances in Cryptology .Springer-Verlag , 1985.47—53[2] Tseng Y, Jan Y.A novel ID-based group signature .In :Hwang TL, Lenstra AK, eds .1998 International Computer Symposium .Workshop onCryptology and Information Securi ty , Taiwan , 1998 .159—164[3] Popescu C .Group signature schemes based on the diffi culty of computation of approximate e-th roots .In :Proceedings of Protocols forMultimediaSystems (PROMS 2000).Poland , 2000.325—331[4] Rivest RL, Shamir A, Tauman Y.How to leak a secret.In :Boyd C , ed.Proc of Asiacrypt01 , LNCS .Springer-Verlag , 2001, 2248 :552—565