Cryptology ePrint Archive: Report 2020/569

QA-NIZK Arguments of Same Opening for Bilateral Commitments

Carla Rāfols and Javier Silva

Abstract: Zero-knowledge proofs of satisfiability of linear equations over a group are often used as a building block of more complex protocols. In particular, in an asymmetric bilinear group we often have two commitments in different sides of the pairing, and we want to prove that they open to the same value. This problem was tackled by González, Hevia and Rāfols (ASIACRYPT 2015), who presented an aggregated proof, in the QA-NIZK setting, consisting of only four group elements. In this work, we present a more efficient proof, which is based on the same assumptions and consists of three group elements. We argue that our construction is optimal in terms of proof size.

Category / Keywords: public-key cryptography / pairing-based cryptography, zero-knowledge proofs, commitments

Original Publication (in the same form): Africacrypt 2020

Date: received 15 May 2020

Contact author: javier silva at upf edu, carla rafols@upf edu

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Version: 20200516:071356 (All versions of this report)

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