Topic

# Zero-knowledge proof

About: Zero-knowledge proof is a research topic. Over the lifetime, 1132 publications have been published within this topic receiving 37942 citations. The topic is also known as: zero-knowledge protocol & ZKP.

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TL;DR: A computational complexity theory of the “knowledge” contained in a proof is developed and examples of zero-knowledge proof systems are given for the languages of quadratic residuosity and 'quadratic nonresiduosity.

Abstract: Usually, a proof of a theorem contains more knowledge than the mere fact that the theorem is true. For instance, to prove that a graph is Hamiltonian it suffices to exhibit a Hamiltonian tour in it; however, this seems to contain more knowledge than the single bit Hamiltonian/non-Hamiltonian.In this paper a computational complexity theory of the “knowledge” contained in a proof is developed. Zero-knowledge proofs are defined as those proofs that convey no additional knowledge other than the correctness of the proposition in question. Examples of zero-knowledge proof systems are given for the languages of quadratic residuosity and 'quadratic nonresiduosity. These are the first examples of zero-knowledge proofs for languages not known to be efficiently recognizable.

3,117 citations

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TL;DR: In this article, it was shown that all languages in NP have zero-knowledge interactive proofs, which are probabilistic and interactive proofs that, for the members of a language, efficiently demonstrate membership in the language without conveying any additional knowledge.

Abstract: In this paper the generality and wide applicability of Zero-knowledge proofs, a notion introduced by Goldwasser, Micali, and Rackoff is demonstrated. These are probabilistic and interactive proofs that, for the members of a language, efficiently demonstrate membership in the language without conveying any additional knowledge. All previously known zero-knowledge proofs were only for number-theoretic languages in NP fl CONP. Under the assumption that secure encryption functions exist or by using "physical means for hiding information, '' it is shown that all languages in NP have zero-knowledge proofs. Loosely speaking, it is possible to demonstrate that a CNF formula is satisfiable without revealing any other property of the formula, in particular, without yielding neither a satis@ing assignment nor properties such as whether there is a satisfying assignment in which xl = X3 etc. It is also demonstrated that zero-knowledge proofs exist "outside the domain of cryptography and number theory. " Using no assumptions. it is shown that both graph isomorphism and graph nonisomor- phism have zero-knowledge interactive proofs. The mere existence of an interactive proof for graph nonisomorphism is interesting, since graph nonisomorphism is not known to be in NP and hence no efficient proofs were known before for demonstrating that two graphs are not isomorphic.

1,366 citations

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TL;DR: This paper defines the definition of unrestricted input zero- knowledge proofs of knowledge in which the prover demonstrates possession of knowledge without revealing any computational information whatsoever (not even the one bit revealed in zero-knowledge proofs of assertions).

Abstract: In this paper we extend the notion of interactive proofs of assertions to interactive proofs of knowledge. This leads to the definition of unrestricted input zero-knowledge proofs of knowledge in which the prover demonstrates possession of knowledge without revealing any computational information whatsoever (not even the one bit revealed in zero-knowledge proofs of assertions). We show the relevance of these notions to identification schemes, in which parties prove their identity by demonstrating their knowledge rather than by proving the validity of assertions. We describe a novel scheme which is provably secure if factoring is difficult and whose practical implementations are about two orders of magnitude faster than RSA-based identification schemes. The advantages of thinking in terms of proofs of knowledge rather than proofs of assertions are demonstrated in two efficient variants of the scheme: unrestricted input zero-knowledge proofs of knowledge are used in the construction of a scheme which needs no directory; a version of the scheme based on parallel interactive proofs (which are not known to be zero knowledge) is proved secure by observing that the identification protocols are proofs of knowledge.

1,187 citations

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12 May 1996

TL;DR: This work examplify the verifier designation method for the confirmation protocol for undeniable signatures, and demonstrates how a trap-door commitment scheme can be used to construct designated verifier proofs, both interactive and non-interactive.

Abstract: For many proofs of knowledge it is important that only the verifier designated by the confirmer can obtain any conviction of the correctness of the proof. A good example of such a situation is for undeniable signatures, where the confirmer of a signature wants to make sure that only the intended verifier(s) in fact can be convinced about the validity or invalidity of the signature.
Generally, authentication of messages and off-the-record messages are in conflict with each other. We show how, using designation of verifiers, these notions can be combined, allowing authenticated but private conversations to take place. Our solution guarantees that only the specified verifier can be convinced by t,he proof, even if he shares all his secret information with entities that want to get convinced.
Our solution is based on trap-door conim.itments [4], allowing the designated verifier to open up commitments in any way he wants. We demonstrate how a trap-door commitment scheme can be uscd to construct designated verifier proofs, both interactive and non-interactive. We examplify the verifier designation method for the confirmation protocol for undeniable signatures.

870 citations

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13 Apr 2008TL;DR: In this article, a general methodology for constructing very simple and efficient non-interactive zero-knowledge proofs and noninteractive witness-indistinguishable proofs that work directly for groups with a bilinear map, without needing a reduction to Circuit Satisfiability is presented.

Abstract: Non-interactive zero-knowledge proofs and non-interactive witnessindistinguishable proofs have played a significant role in the theory of cryptography. However, lack of efficiency has prevented them from being used in practice. One of the roots of this inefficiency is that non-interactive zeroknowledge proofs have been constructed for general NP-complete languages such as Circuit Satisfiability, causing an expensive blowup in the size of the statement when reducing it to a circuit. The contribution of this paper is a general methodology for constructing very simple and efficient non-interactive zero-knowledge proofs and non-interactive witness-indistinguishable proofs that work directly for groups with a bilinear map, without needing a reduction to Circuit Satisfiability.
Groups with bilinear maps have enjoyed tremendous success in the field of cryptography in recent years and have been used to construct a plethora of protocols. This paper provides non-interactive witness-indistinguishable proofs and non-interactive zero-knowledge proofs that can be used in connection with these protocols. Our goal is to spread the use of non-interactive cryptographic proofs from mainly theoretical purposes to the large class of practical cryptographic protocols based on bilinear groups.

855 citations