Efficient group signatures without trapdoors

Group signature schemes are fundamental cryptographic tools that enable unlinkably anonymous authentication, in the same fashion that digital signatures provide the basis for strong authentication protocols. In this paper we present the first group signature scheme with constant-size parameters that does not require any group member, including group managers, to know trapdoor secrets. This novel type of group signature scheme allows public parameters to be shared among organizations. Such sharing represents a highly desirable simplification over existing schemes, which require each organization to maintain a separate cryptographic domain.