## CryptoDB

### Paper: Lunar: a Toolbox for More Efficient Universal and Updatable zkSNARKs and Commit-and-Prove Extensions

Authors: Matteo Campanelli , Aarhus University Antonio Faonio , EURECOM Dario Fiore , IMDEA Software Institute Anaïs Querol , IMDEA Software Institute, Universidad Politécnica de Madrid Hadrián Rodríguez , IMDEA Software Institute DOI: 10.1007/978-3-030-92078-4_1 Search ePrint Search Google Slides ASIACRYPT 2021 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 zk-SNARKs (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.
##### BibTeX
@inproceedings{asiacrypt-2021-31446,
title={Lunar: a Toolbox for More Efficient Universal and Updatable zkSNARKs and Commit-and-Prove Extensions},
publisher={Springer-Verlag},
doi={10.1007/978-3-030-92078-4_1},
author={Matteo Campanelli and Antonio Faonio and Dario Fiore and Anaïs Querol and Hadrián Rodríguez},
year=2021
}