Ring Signature Scheme from Multilinear Maps in the Standard Model

Ring signature is a group-oriented digital signature with anonymity. In 2006, Bencer et al. formalized stronger security definitions for ring signatures and proposed a concrete ring signature scheme based on Waters signature. However, their ring signature scheme can only support a two-user setting, and has relax security reduction. In this paper, we describe a ring signature scheme with multi users from multilinear maps. And then we prove that the proposed scheme is anonymous against full key exposure and unforgeable against chosen-subring attacks based on multilinear computational Diffie-Hellman assumption. Furthermore, the security reduction of our scheme is tighter than that of Bencer et al.'s scheme by using an optimal security reduction Waters signature.