### Shorter Pairing-based Arguments under Standard Assumptions

Alonso Gonzalez and Carla Rafols

##### Abstract

This paper constructs efficient non-interactive arguments for correct evaluation of arithmetic and boolean circuits with proof size $O(d)$ group elements, where $d$ is the multiplicative depth of the circuit, under falsifiable assumptions. This is achieved by combining techniques from SNARKs and QA-NIZK arguments of membership in linear spaces. The first construction is very efficient (the proof size is $\approx4d$ group elements and the verification cost is $\approx 4d$ pairings and $O(n+n'+d)$ exponentiations, where $n$ is the size of the input and $n'$ of the output) but one type of attack can only be ruled out assuming the knowledge soundness of QA-NIZK arguments of membership in linear spaces. We give an alternative construction which replaces this assumption with a decisional assumption in bilinear groups at the cost of approximately doubling the proof size. The construction for boolean circuits can be made zero-knowledge with Groth-Sahai proofs, resulting in a NIZK argument for circuit satisfiability based on falsifiable assumptions in bilinear groups of proof size $O(n+d)$. Our main technical tool is what we call an argument of knowledge transfer''. Given a commitment $C_1$ and an opening $x$, such an argument allows to prove that some other commitment $C_2$ opens to $f(x)$, for some function $f$, even if $C_2$ is not extractable. We construct very short, constant-size, pairing-based arguments of knowledge transfer with constant-time verification for any linear function and also for Hadamard products. These allow to transfer the knowledge of the input to lower levels of the circuit.

Available format(s)
Category
Cryptographic protocols
Publication info
A minor revision of an IACR publication in Asiacrypt 2019
Keywords
zero knowledge
Contact author(s)
carla rafols @ upf edu
History
2019-12-19: revised
See all versions
Short URL
https://ia.cr/2019/326

CC BY

BibTeX

@misc{cryptoeprint:2019/326,
author = {Alonso Gonzalez and Carla Rafols},
title = {Shorter Pairing-based Arguments under Standard Assumptions},
howpublished = {Cryptology ePrint Archive, Paper 2019/326},
year = {2019},
note = {\url{https://eprint.iacr.org/2019/326}},
url = {https://eprint.iacr.org/2019/326}
}

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