Extending the ring signature scheme for individual person

a novel ring signature scheme for general subsets of a group is proposed.In the scheme

the members of signing subset firstly construct a group including themselves

then construct a set of subsets including the signing subset

namely the authorized subsets.The signature is generated by co-operation of all members of the signing subset.The verifier can verify whether the signature is generated by one of the authorized subsets

but s/he cannot find out the detailed signing subset.The scheme is proved secure under the random oracle model.And the results of complexity analysis show that the scheme is efficient.