Crate light_poseidon

Expand description

light-poseidon is a Poseidon hash implementation in Rust created for Light Protocol.

Parameters

The library provides pre-generated parameters over the BN254 curve, however it can work with any parameters provided as long as developers take care of generating the round constants.

Parameters provided by the library are:

x^5 S-boxes
3 prime fields (one zero prime field and two inputs from the caller)
8 full rounds and 57 partial rounds

Output type

Poseidon type implements two traits which serve the purpose of returning the calculated hash in different representations:

PoseidonBytesHasher with the hash_bytes method which returns a byte array.
PoseidonHasher with the hash method which returns ark_ff::PrimeField. Might be useful if you want to immediately process the result with an another library which works with ark_ff::PrimeField types.

Examples

Example with two simple big-endian byte inputs (converted to prime fields) and BN254-based parameters provided by the library, with PoseidonBytesHasher trait and a byte array result:

use light_poseidon::{Poseidon, PoseidonBytesHasher, parameters::bn254_x5_3::poseidon_parameters};
use ark_bn254::Fq;
use ark_ff::{BigInteger, PrimeField};

let params = poseidon_parameters();
let mut poseidon = Poseidon::new(params);

let hash = poseidon.hash_bytes(&[&[1u8; 32], &[2u8; 32]]).unwrap();

println!("{:?}", hash);
// Should print:
// [
//     40, 7, 251, 60, 51, 30, 115, 141, 251, 200, 13, 46, 134, 91, 113, 170, 131, 90, 53,
//     175, 9, 61, 242, 164, 127, 33, 249, 65, 253, 131, 35, 116
// ]

With PoseidonHasher trait and ark_ff::PrimeField result:

use light_poseidon::{Poseidon, PoseidonHasher, parameters::bn254_x5_3::poseidon_parameters};
use ark_bn254::Fq;
use ark_ff::{BigInteger, PrimeField};

let params = poseidon_parameters();
let mut poseidon = Poseidon::new(params);

let input1 = Fq::from_be_bytes_mod_order(&[1u8; 32]);
let input2 = Fq::from_be_bytes_mod_order(&[2u8; 32]);

let hash = poseidon.hash(&[input1, input2]).unwrap();

// Do something with `hash`.

Implementation

The implementation is compatible with the original SageMath implementation, but it was also inspired by the following ones:

Performance

This repository contains a benchmark measuring the performance of this Poseidon implementation for given two random 32 bytes inputs.

To run them, simply use:

cargo bench

This is the result from a host with the following hardware:

AMD Ryzen 9 5950x (base clock: 3.4 GHz, up to: 4.9 GHz)
4 x Corsair Vengeance DDR4 32GB 3600 MHz

poseidon_bn254_x5_3     time:   [21.980 µs 21.997 µs 22.017 µs]
Found 9 outliers among 100 measurements (9.00%)
  4 (4.00%) high mild
  5 (5.00%) high severe

Modules

parameters

Structs

Poseidon

A stateful sponge performing Poseidon hash computation.

PoseidonParameters

Parameters for the Poseidon hash algorithm.