Using a group signature scheme, the members of a group can sign a message with their respective secret keys. The resulting signature can be verified by everyone who knows the common public key, but the signature does not reveal any information about the signer except that she is a member of the group. Usually there exists another entity called the group manager, who can reveal the exact identity of the signer, and handles the adding of users to and the removal of users from the group—usually by issuing or revoking group membership certificates. The anonymity, unlinkability, and anonymity revocation provided by group signatures lends itself for a variety of privacy sensitive applications like voting, bidding, anonymous payment, and anonymous credentials