Practical group signatures from RSA

A group signature scheme allows a member of a given group to anonymously sign a message on behalf of the group. In the case of a later dispute, a designated group manager can open the signature, revoke the anonymity and identify the original signer. This paper presents a new and practical approach to group signatures. A trusted on-line third party is introduced in our scheme to help to realize (1) the "join" of group members, (2) the "opening" of group signatures, and (3) the "revocation" of group membership. Based on classical RSA, a practical group signature scheme is constructed. It is shown that our scheme satisfies all the security requirements of a secure group signature scheme, and the introduction of this third party makes our scheme much more simple and practical than the previous schemes of this kind.