# Zerokit

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A collection of Zero Knowledge modules written in Rust and designed to be used in other system programming environments.

## Overview

Zerokit provides zero-knowledge cryptographic primitives with a focus on performance, security, and usability.
The current focus is on Rate-Limiting Nullifier [RLN](https://github.com/Rate-Limiting-Nullifier) implementation.

Current implementation is based on the following
[specification](https://rfc.vac.dev/vac/raw/rln-v2)
and focused on RLNv2 which allows to set a rate limit for the number of messages that can be sent by a user.

## Features

- **RLN Implementation**: Efficient Rate-Limiting Nullifier using zkSNARK
- **Circom Compatibility**: Uses Circom-based circuits for RLN
- **Cross-Platform**: Support for multiple architectures with cross-compilation
- **FFI-Friendly**: Easy to integrate with other languages
- **WASM Support**: Can be compiled to WebAssembly for web applications

## Architecture

Zerokit currently focuses on RLN (Rate-Limiting Nullifier) implementation using [Circom](https://iden3.io/circom)
circuits through ark-circom, providing an alternative to existing native Rust implementations.

## Build and Test

### Install Dependencies

```bash
make installdeps
```

#### Use Nix to install dependencies

```bash
nix develop
```

### Build and Test All Crates

```bash
make build
make test
```

## Release Assets

We use [`cross-rs`](https://github.com/cross-rs/cross) to cross-compile and generate release assets:

```bash
# Example: Build for specific target
cross build --target x86_64-unknown-linux-gnu --release -p rln
```

## Used By

Zerokit powers zero-knowledge functionality in:

- [**nwaku**](https://github.com/waku-org/nwaku) - Nim implementation of the Waku v2 protocol
- [**js-rln**](https://github.com/waku-org/js-rln) - JavaScript bindings for RLN

## Acknowledgements

- Inspired by [Applied ZKP](https://zkp.science/) group work, including [zk-kit](https://github.com/appliedzkp/zk-kit)
- Uses [ark-circom](https://github.com/gakonst/ark-circom) for zkey and Groth16 proof generation
- Witness calculation based on [circom-witnesscalc](https://github.com/iden3/circom-witnesscalc) by iden3.
The execution graph file used by this code has been generated by means of the same iden3 software.

> [!IMPORTANT]
> The circom-witnesscalc code fragments have been borrowed instead of depending on this crate,
> because its types of input and output data were incompatible with the corresponding zerokit code fragments,
> and circom-witnesscalc has some dependencies, which are redundant for our purpose.

## Documentation

For detailed documentation on each module:

```bash
cargo doc --open
```