Cryptology ePrint Archive: Report 2011/493

From Point Obfuscation To 3-round Zero-Knowledge

Nir Bitansky and Omer Paneth

Abstract: We construct 3-round proofs and arguments with negligible soundness error satisfying two relaxed notions of {\em zero-knowledge}: {\em Weak ZK} and {\em witness hiding} (WH). At the heart of our constructions lie new techniques based on {\em point obfuscation with auxiliary input} (AIPO).

It is known that such protocols cannot be proven secure using black-box reductions (or simulation). Our constructions circumvent these lower bounds, utilizing AIPO (and extensions) as the ``non-black-box component" in the security reduction. We also investigate the relation between AIPO and the assumptions previously used to achieve 3-round ZK.

Category / Keywords: cryptographic protocols / Zero-Knowledge, Obfuscation, Point Obfuscation, Witness-Hiding,

Date: received 11 Sep 2011, last revised 21 Sep 2011

Contact author: omer at bu edu

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Version: 20110921:185422 (All versions of this report)

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