GDH group-based signature scheme with linkability

Abstract

Recently, a linkable ring signature scheme (called the LWW signature scheme), exhibiting the properties of anonymity, linkability and spontaneity, was presented. Its security is based on the decision Diffie–Hellman (DDH) problem. The distinguishing feature of the LWW signature scheme that differentiates it from other ring signature schemes is linkability, i.e. two signatures by the same signer can be linked. The LWW scheme can be used to construct new efficient e-voting systems. The drawback of the LWW scheme is that it works well on a group where the DDH problem is hard, but does not work on a GDH group where the DDH problem is easy and the computational Diffie–Hellman (CDH) problem is hard. In this paper, a linkable ring signature scheme is presented, based on a GDH group with anonymity, linkability and spontaneity. The security of the scheme is reduced to the discrete logarithm and a new intractability assumption (called DPDH problem) under the random oracle model.