A New Strong Designated Verifier Signature Scheme

A strong designated verifier signature (SDVS) scheme allows a signer to convince only the designated verifier that the signature is made by the signer, where the designated verifier cannot transfer the signature to a third party and no third party can ever verify the validity of the signature. Since 1996, many SDVS schemes based on various single hard problems were introduced. Although these schemes seem secure today, there is a possibility of an adversary finding a solution for these hard problems in the future and if this happens, then the SDVS schemes based on single hard problems will no longer be secure. In this paper, we develop a new SDVS scheme based on two hard problems; factoring and discrete logarithm problems, providing a greater security level than the SDVS schemes based on single hard problems. Our scheme satisfies the properties of an SDVS scheme.