# sonobe

Experimental folding schemes library implemented jointly by [0xPARC](https://0xparc.org/) and [PSE](https://pse.dev).

<img align="right" style="width:30%;min-width:250px;margin-bottom:20px;" src="https://privacy-scaling-explorations.github.io/sonobe-docs/imgs/sonobe.png">

<b>Sonobe</b> is a modular library to fold arithmetic circuit instances in an Incremental Verifiable computation (IVC) style. It features multiple folding schemes and decider setups, allowing users to pick the scheme which best fit their needs.
<br><br>
Sonobe is conceived as an exploratory effort with the aim to push forward the practical side of folding schemes and advancing towards onchain (EVM) verification.
<br><br>
<i>"The <a href="https://en.wikipedia.org/wiki/Sonobe">Sonobe module</a> is one of the many units used to build modular origami. The popularity of Sonobe modular origami models derives from the simplicity of folding the modules, the sturdy and easy assembly, and the flexibility of the system."</i>

<br>

> **Warning**: experimental code, do not use in production.<br>
> The code has not been audited. Several optimizations are also pending. Our focus so far has been on implementing the Nova and CycleFold schemes and achieving onchain (EVM) verification.

## Schemes implemented

Folding schemes implemented:

- [Nova: Recursive Zero-Knowledge Arguments from Folding Schemes](https://eprint.iacr.org/2021/370.pdf), Abhiram Kothapalli, Srinath Setty, Ioanna Tzialla. 2021
- [CycleFold: Folding-scheme-based recursive arguments over a cycle of elliptic curves](https://eprint.iacr.org/2023/1192.pdf), Abhiram Kothapalli, Srinath Setty. 2023

Work in progress:

- [HyperNova: Recursive arguments for customizable constraint systems](https://eprint.iacr.org/2023/573.pdf), Abhiram Kothapalli, Srinath Setty. 2023
- [ProtoGalaxy: Efficient ProtoStar-style folding of multiple instances](https://eprint.iacr.org/2023/1106.pdf), Liam Eagen, Ariel Gabizon. 2023

## Available frontends

Available frontends to define the folded circuit:

- [arkworks](https://github.com/arkworks-rs), arkworks contributors
- [Circom](https://github.com/iden3/circom), iden3, 0Kims Association

## Usage

### Docs

Detailed usage and design documentation can be found at [Sonobe docs](https://privacy-scaling-explorations.github.io/sonobe-docs/).

### Folding Schemes introduction

Folding schemes efficitently achieve incrementally verifiable computation (IVC), where the prover recursively proves the correct execution of the incremental computations.
Once the IVC iterations are completed, the IVC proof is compressed into the Decider proof, a zkSNARK proof which proves that applying $n$ times the $F$ function (the circuit being folded) to the initial state ($z_0$) results in the final state ($z_n$).


<p align="center">
    <img src="https://privacy-scaling-explorations.github.io/sonobe-docs/imgs/folding-main-idea-diagram.png" style="width:70%;" />
</p>

Where $w_i$ are the external witnesses used at each iterative step.

In other words, it allows to prove efficiently that $z_n = F(...~F(F(F(F(z_0, w_0), w_1), w_2), ...), w_{n-1})$.


### Overview of sonobe

Sonobe is a folding schemes modular library to fold arithmetic circuit instances in an incremental verifiable computation (IVC) style. It also provides the tools required to generate a zkSNARK proof out of an IVC proof and to verify it on Ethereum's EVM.

The development flow using Sonobe looks like:

1. Define a circuit to be folded
2. Set which folding scheme to be used (eg. Nova with CycleFold)
3. Set a final decider to generate the final proof (eg. Spartan over Pasta curves)
4. Generate the the decider verifier

<p align="center">
    <img src="https://privacy-scaling-explorations.github.io/sonobe-docs/imgs/sonobe-lib-pipeline.png"/>
</p>

The folding scheme and decider used can be swapped with a few lines of code (eg. switching from a Decider that uses two Spartan proofs over a cycle of curves, to a Decider that uses a single Groth16 proof over the BN254 to be verified in an Ethereum smart contract).

The [Sonobe docs](https://privacy-scaling-explorations.github.io/sonobe-docs/) contain more details about the usage and design of the library.

Complete examples can be found at [folding-schemes/examples](https://github.com/privacy-scaling-explorations/sonobe/tree/main/examples)

## License

Sonobe is [MIT Licensed](https://github.com/privacy-scaling-explorations/sonobe/blob/main/LICENSE).

## Acknowledgments

This project builds on top of multiple [arkworks](https://github.com/arkworks-rs) libraries. It uses Espresso system's [virtual polynomial](https://github.com/EspressoSystems/hyperplonk/blob/main/arithmetic/src/virtual_polynomial.rs) abstraction and its [SumCheck](https://github.com/EspressoSystems/hyperplonk/tree/main/subroutines/src/poly_iop/sum_check) implementation.

The Solidity templates used in `nova_cyclefold_verifier.sol`, use [iden3](https://github.com/iden3/snarkjs/blob/master/templates/verifier_groth16.sol.ejs)'s Groth16 implementation and a KZG10 Solidity template adapted from [weijiekoh/libkzg](https://github.com/weijiekoh/libkzg).

In addition to the direct code contributors who make this repository possible, this project has been made possible by many conversations with [Srinath Setty](https://github.com/srinathsetty), [Lev Soukhanov](https://github.com/levs57), [Matej Penciak](https://github.com/mpenciak), [Adrian Hamelink](https://github.com/adr1anh), [François Garillot](https://github.com/huitseeker), [Daniel Marin](https://github.com/danielmarinq), [Han Jian](https://github.com/han0110), [Wyatt Benno](https://github.com/wyattbenno777), [Nikkolas Gailly](https://github.com/nikkolasg) and [Nalin Bhardwaj](https://github.com/nalinbhardwaj), to whom we are grateful.