Lunar: A Toolbox for More Efficient Universal and Updatable zkSNARKs and Commit-and-Prove Extensions

Matteo Campanelli*, Antonio Faonio, Dario Fiore, Anaïs Querol, Hadrián Rodríguez

*Corresponding author for this work

Research output: Contribution to book/anthology/report/proceedingArticle in proceedingsResearchpeer-review

Abstract

We study how to construct zkSNARKs whose SRS is universal and updatable, i.e., valid for all relations within a size-bound and to which a dynamic set of participants can indefinitely add secret randomness. Our focus is: efficient universal updatable zkSNARKs with linear-size SRS and their commit-and-prove variants. We both introduce new formal frameworks and techniques, as well as systematize existing ones. We achieve a collection of zkSNARKs with different tradeoffs. One of our schemes achieves the smallest proof size and proving time compared to the state of art for proofs for arithmetic circuits. The language supported by this scheme is a variant of R1CS that we introduce, called R1CS-lite. Another of our constructions directly supports standard R1CS and achieves the fastest proving time for this type of constraints. These results stem from different contributions: (1) a new algebraically-flavored variant of IOPs that we call Polynomial Holographic IOPs (PHPs); (2) a new compiler that combines our PHPs with commit-and-prove zkSNARKs (CP-SNARKs) for committed polynomials; (3) pairing-based realizations of these CP-SNARKs for polynomials; (4) constructions of PHPs for R1CS and R1CS-lite. Finally, we extend the compiler in item (2) to yield commit-and-prove universal zkSNARKs.

Original languageEnglish
Title of host publicationAdvances in Cryptology – ASIACRYPT 2021 : 27th International Conference on the Theory and Application of Cryptology and Information Security, Singapore, December 6–10, 2021, Proceedings, Part III
EditorsMehdi Tibouchi, Huaxiong Wang
Number of pages31
PublisherSpringer
Publication date2021
Pages3-33
ISBN (Print)9783030920777
DOIs
Publication statusPublished - 2021
Event27th International Conference on Theory and Application of Cryptology and Information Security, ASIACRYPT 2021 - Virtual, Online
Duration: 6 Dec 202110 Dec 2021

Conference

Conference27th International Conference on Theory and Application of Cryptology and Information Security, ASIACRYPT 2021
CityVirtual, Online
Period06/12/202110/12/2021
SeriesLecture Notes in Computer Science
Volume13092
ISSN0302-9743

Keywords

  • IOP
  • Polynomial commitments
  • Universal SRS
  • zkSNARK

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