keccak256-circom/README.md

# keccak256-circom [![Test](https://github.com/vocdoni/keccak256-circom/workflows/Test/badge.svg)](https://github.com/vocdoni/keccak256-circom/actions?query=workflow%3ATest)

Keccak256 hash function (ethereum version) implemented in [circom](https://github.com/iden3/circom). Spec: https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf

**Warning**: WIP, this is an experimental repo.

## Status
Initial version works, compatible with Ethereum version of Keccak256.

It needs around `150848` (`151k`) constraints. 
> For context: [Rapidsnark](https://github.com/iden3/rapidsnark) proof generation time:
> - 1.1M constraints -> 7 seconds (8 CPU)
> - 128M constraints -> <2min (64 CPU)

## Usage
- import the lib in the `package.json`:
```
"dependencies": {
	"keccak256-circom": "git+https://github.com/vocdoni/keccak256-circom"
}
```

- Usage:
```
pragma circom 2.0.0;

include "../node_modules/keccak256-circom/circuits/keccak.circom";

// for a input & output of 32 bytes:
component main = Keccak(32*8, 32*8);
```