We propose a concrete procedure of a Σ-protocol proving knowledge that a set of witnesses satisfies a monotone predicate in witness-indistinguishable manner. Inspired by the high-level proposal by Cramer, Damg̊ard and Schoenmakers at CRYPTO ’94, we construct the concrete procedure by extending the so-called OR-proof. Next, using as a witness a credential-bundle of the Fiat-Shamir signatures, we ...
