Proofs of Partial Knowledge and Simplified Design of Witness Hiding Protocols

Suppose we are given a proof of knowledge P in which a prover demonstrates that he knows a solution to a given problem instance. Suppose also that we have a secret sharing scheme S on n participants. Then under certain assumptions on P and S, we show how to transform P into a witness indistinguishable protocol, in which the prover demonstrates knowledge of the solution to some subset of n problem instances out of a collection of subsets defined by S. For example, using a threshold scheme, the prover can show that he knows at least d out of n solutions without revealing which d instances are involved. If the instances are independently generated, we get a witness hiding protocol, even if P did not have this property. Our results can be used to efficiently implement general forms of group oriented identification and signatures. Our transformation produces a protocol with the same number of rounds as P and communication complexity n times that of P. Our results use no unproven complexity ...

• Type: Conference
• Year: 1994
• Where: CRYPTO
• Authors: Ronald Cramer, Ivan Damgård, Berry Schoenmakers
• Keywords: CRYPTO 1994, Cryptology, Problem Instances, Prover, Prover Demonstrates Knowledge