Improved ID-based Ring Signature Scheme with Constant-size Signatures

Ring signature enable a user to sign a message on behalf of the ring, without revealing the actual signer. Constant-size ring signature is the ring scheme that the size of the signature does not grow with the size of the ring(or group), so it is practical for large rings. In this paper we use the Collision Resistant Accumulator from bilinear pairing to construct an identity-based ring signature scheme with constant-size signature. Our scheme actually is an improvement on the modified version of the scheme proposed by Nguyen, but we greatly improved the efficiency in terms of computational complexity and signature size. To the best of our knowledge, our scheme is the most efficient secure ID-based ring signature with constant-size based on accumulator proposed to date. Our scheme is proven secure in the random oracle model based on a simplified and general Forking Lemma under the k-strong Diffie-Hellman assumption.