Public-coin concurrent zero-knowledge in the global hash model

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Public-coin zero-knowledge and concurrent zero-knowledge ( cZK ) are two classes of zero knowledge protocols that guarantee some additional desirable properties. Still, to this date no protocol is known that is both public-coin and cZK for a language outside BPP. Furthermore, it is known that no such protocol can be black-box ZK [Pass et.al, Crypto 09]. We present a public-coin concurrent ZK protocol for any NP language. The protocol assumes that all verifiers have access to a globally specified function, drawn from a collision resistant hash function family. (This model, which we call the Global Hash Function, or GHF model, can be seen as a restricted case of the non-programmable reference string model.) We also show that the impossibility of black-box public-coin cZK extends also to the GHF model. Our protocol assumes CRH functions against quasi-polynomial adversaries and takes O(log 1 + ε n) rounds for any ε > 0, where n is the security parameter. Our techniques combine those for (non-public-coin) black-box cZK with Barak's non-black-box technique for public-coin constant-round ZK. As a corollary we obtain the first simultaneously resettable zero-knowledge protocol with O(log1 + ε n) rounds, in the GHF model.

Original languageEnglish
Title of host publicationTheory of Cryptography - 10th Theory of Cryptography Conference, TCC 2013, Proceedings
Pages80-99
Number of pages20
DOIs
StatePublished - 2013
Event10th Theory of Cryptography Conference, TCC 2013 - Tokyo, Japan
Duration: 3 Mar 20136 Mar 2013

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume7785 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference10th Theory of Cryptography Conference, TCC 2013
Country/TerritoryJapan
CityTokyo
Period3/03/136/03/13

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