(t, n) threshold untraceable signatures

A (t, n) threshold signature scheme is one which enables any t or more shareholders to cooperatively generate a group signature. Based on the traceability of the signers, threshold signatures can further be classified into (1) threshold traceable signatures, where the identities of the signers, who generate the signature, can be traced by the system; and (2) threshold untraceable signatures, where the signers of a signature cannot be traced. This paper distinguishes the applications of threshold signatures of both types and also proposes a threshold untraceable signature scheme. The new signature scheme can be augmented to give the original signers the ability to prove that they are the true signers.