Cryptology ePrint Archive: Report 2020/235

Statistical Zaps and New Oblivious Transfer Protocols

Vipul Goyal and Abhishek Jain and Zhengzhong Jin and and Giulio Malavolta

Abstract: We study the problem of achieving statistical privacy in interactive proof systems and oblivious transfer -- two of the most well studied two-party protocols -- when limited rounds of interaction are available. Statistical Zaps: We give the first construction of statistical Zaps, namely, two-round statistical witness-indistinguishable (WI) protocols with a public-coin verifier. Our construction achieves computational soundness based on the quasi-polynomial hardness of learning with errors.

Three-Round Statistical Receiver-Private Oblivious Transfer: We give the first construction of a three-round oblivious transfer (OT) protocol -- in the plain model -- that achieves statistical privacy for receivers and computational privacy for senders against malicious adversaries, based on polynomial-time assumptions. The round-complexity of our protocol is optimal.

We obtain our first result by devising a public-coin approach to compress sigma protocols, without relying on trusted setup. To obtain our second result, we devise a general framework via a new notion of statistical hash commitments that may be of independent interest.

Category / Keywords: cryptographic protocols / Zaps, Oblivious Transfer

Original Publication (with major differences): IACR-EUROCRYPT-2020

Date: received 21 Feb 2020, last revised 21 Feb 2020

Contact author: vipul at cmu edu,abhishek@cs jhu edu,zjin12@jhu edu,giulio malavolta@hotmail it

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Version: 20200224:144450 (All versions of this report)

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