Group signature system and schemes with controllable linkability

The present invention provides the group signature system and method for providing controllable connections. The connectivity means a given, "signed value that was generated from the key signing." The present invention supports the dynamic membership (dynamic membership) for the user to join / leave, and provides all the features of the known signature group by default and in addition thereto provides controllable connections. Participants in the group signature are largely composed of key issuer (issuer), resolver (opener), linkers (linker), signatory (signer) (or user), and the verifier (verifier). Signer is used to being issued a key that is used for anonymous authentication key from the issuer after a JOIN to create this post anonymity based signatures. Whether the signer is who verification using the public key group who can see that without knowing the signature is created, legitimate users. For the future, the key is lost or you leave, check who can produce proof of the value that can prove who you are by your own confirmation key. The connection can be found two signature values ​​given by their connection key to whether the signer is who they are generated from the same user without knowing.