# Circuits

[![NPM Package][circuits-npm-badge]][circuits-npm-link]
[![Actions Status][circuits-actions-badge]][circuits-actions-link]

This package contains the zk-SNARK circuits written in Circom 2.0.

The main circuits are:

* `processMessages.circom`
* `tallyVotes.circom`
* (optional) `subsidy.circom`

The rest of the circuits are utilities templates that are required for the main circuits to work correctly. These include utilities such as float math, conversion of private keys, and Poseidon hashing/encryption.

Please refer to the [documentation](https://privacy-scaling-explorations.github.io/maci/circuits.html) for a more in depth explanation.

## Build

### Prerequisites

Before building the project, make sure you have the following dependencies installed:

- [circom](https://docs.circom.io/downloads/downloads/)

### Building MACI circuits

To build the two main circuits of MACI, run the following commands:

```
circom --r1cs --sym --wasm --output ./build circom/test/processMessages_test.circom
circom --r1cs --sym --wasm --output ./build circom/test/tallyVotes_test.circom
```

Please note that the circuit is configured with testing purpose parameters, which means it can only handle a limited amount of messages (up to 25 messages). For more information on the parameters and how to configure them, refer to [this page](https://privacy-scaling-explorations.github.io/maci/circuits.html#compile-circuits).

### Generating and Validating ZK Proofs

To generate and validate ZK proofs from the artifacts produced by `circom`, you will need [`snarkjs`](https://github.com/iden3/snarkjs#groth16-1).

## Testing

To test the circuits package, please use `npm run test`. This will run all of the tests inside the tests folder.

To run individual tests, you can use the following commands (for all other circuits please refer to the `package.json` scripts section):

* `npm run test-processMessages` to run the tests for the `processMessages` circuit.
* `npm run test-tallyVotes` to run the tests for the `tallyVotes` circuit.

[circuits-npm-badge]: https://img.shields.io/npm/v/maci-circuits.svg
[circuits-npm-link]: https://www.npmjs.com/package/maci-circuits
[circuits-actions-badge]: https://github.com/privacy-scaling-explorations/maci/actions/workflows/circuit-build.yml/badge.svg
[circuits-actions-link]: https://github.com/privacy-scaling-explorations/maci/actions?query=workflow%3ACircuit