On the Soundness of Restricted Universal Designated Verifier Signatures and Dedicated Signatures
Abstract
In 2006, Huang, Susilo, Mu and Zhang proposed the concept of \emph{restricted universal designated verifier signatures} while Klonowski, Kubiak, Kutylowski and Lauks proposed independently the \emph{dual} primitive of \emph{dedicated signatures}. In both notions, a signature holder can convince one or more verifiers of his knowledge of a digital signature, but cannot exploit this knowledge without being \emph{punished} for that. In this paper, we state that a signature holder may generically provide a proof that it has a certain signature without being punished and that consequently both primitives cannot fulfill their alleged security goals. To demonstrate the feasibility of this claim, we propose the first non-interactive universal designated verifier proof of the possession of an Elgamal or a DSA signature in the random oracle model. This construction may be of independent interest.
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