Cryptology ePrint Archive: Report 2008/524

Round-Optimal Zero-Knowledge Proofs of Knowledge for NP

Li Hongda and Feng dengguo and Li Bao and Xue Haixia

Abstract: It is well known that all the known black-box zero-knowledge proofs of knowledge for NP are non-constant-round. Whether there exit constant-round black-box zero-knowledge proofs of knowledge for all NP languages under certain standard assumptions is a open problem. This paper focuses on the problem and give a positive answer by presenting two constructions of constant-round (black-box) zero-knowledge proofs of knowledge for the HC (Hamiltonian Cycle) problem. By the recent result of Katz, our second construction which relies on the existence of claw-free functions has optimal round complexity (5-round) assuming the polynomial hierarchy does not collapse.

Category / Keywords: cryptographic protocols / zero knowledge

Date: received 15 Dec 2008

Contact author: hdli at gucas ac cn

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Version: 20081216:124657 (All versions of this report)

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