Universal designated verifier signatures with threshold-signers

Abstract

The privacy and anonymity of a signer and the integrity and authenticity of a message are important. Generally, whenever the signer states the authenticity of a message (by producing a signature on that message), the privacy and anonymity of that signer on the respective message will immediately be exposed. Universal Designated Verifier Signature is a cryptographic primitive that is designed to preserve the signer's authenticity together with limiting the signer's privacy. This is obtained by allowing any signature holder to convince a third party that the signature produced by the signer is authentic. In this work, we extend this notion by controlling the ability of the signature holder to convince any verifier if and only if the signature holder holds sufficient signatures from n signers on the same message. This kind of primitives is very useful in many scenarios. We formalize this notion as a universal designated verifier signature with threshold-signers and provide a concrete scheme to realize it. © 2009 Springer-Verlag Berlin Heidelberg.