A group-oriented anonymous signature scheme with subliminal channel

In the conventional group signature scheme, the group manager can identify the actual identity of the signer. But in some cases, this is not desired. In this paper, we propose a group-oriented anonymous signature scheme, which is unconditionally anonymous, namely, any group member can sign anonymously on behalf of the group, and no one (including the group center) can trace the actual identity of the signer. At the same time, any group member can send subliminal message to the authenticated receiver on behalf of the group. Comparing with the Ring signature and 1-out-of-n signature which can also realize unconditional signer-anonymity, our scheme has the following advantages: the size of signature and public key is independent of the group's number.