A Group-Oriented Strong Designated Verifier Signature Scheme with Constant-Size Signatures

A strong designated verifier signature (SDVS) scheme only permits an intended verifier to validate the signature by employing his/her private key. Meanwhile, for the sake of signer anonymity, the designated verifier is also able to generate a computationally indistinguishable transcript, which prevents the designated verifier from arbitrarily transferring his conviction to any third party. To extend the applications of conventional SDVS schemes, in this paper, we propose a group-oriented strong designated verifier signature (GO-SDVS) scheme from bilinear pairings. In particular, our scheme allows a group of signers to cooperatively generate a signature for a designated verifier. A significant property of our mechanism is constant-size signatures, i.e., the signature length remains constant when the number of involved signers increases. We also prove that the proposed GO-SDVS scheme is secure against adaptive chosen-message attacks in the random oracle model and fulfills the essential properties of signer ambiguity and non-transferability.