Crate pso_poseidon 

pso-poseidon is a Poseidon hash implementation in Rust created for PSO based on light-poseidon library.

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
• width - 2 ≤ t ≤ 13
• inputs - 1 ≤ n ≤ 12
• 8 full rounds and partial rounds depending on t: [56, 57, 56, 60, 60, 63, 64, 63, 60, 66, 60, 65]

Output type

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

• 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

With PoseidonHasher trait and ark_ff::PrimeField result:

use ark_bn254::Fr;
use ark_ff::PrimeField;
use pso_poseidon::{Poseidon, PoseidonHasher};

let mut poseidon = Poseidon::<Fr>::new_circom(2).unwrap();

let input1 = Fr::from_le_bytes_mod_order(&[1u8; 32]);
let input2 = Fr::from_le_bytes_mod_order(&[2u8; 32]);

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

// Do something with `hash`.

Poseidon2

Poseidon2 is a separate, generic BN254 Poseidon2 hash, bit-compatible with noir’s in-circuit poseidon2 (Barretenberg’s permutation + sponge). Use it for off-circuit hashing that must reproduce an in-circuit Poseidon2 result. It shares no parameters with the circom-compatible Poseidon above — Poseidon2 is a distinct construction. BN254 is built in via Poseidon2::<Fr>::new(); other fields supply their own constants.

use ark_bn254::Fr;
use pso_poseidon::{Poseidon2, PoseidonHasher};

let mut poseidon2 = Poseidon2::<Fr>::new();
let _hash = poseidon2.hash(&[Fr::from(1u64), Fr::from(2u64)]).unwrap();

Field Arithmetic

This library uses ark-ff for field arithmetic. While ark-ff carries an academic disclaimer, it is widely adopted in production by major projects including Aleo, Penumbra, Mina (Kimchi), and Espresso Systems.

Implementation

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

• circomlibjs
• zero-knowledge-gadgets
• light-poseidon

Security

This library has been audited by Veridise. You can read the audit report here.

Re-exports

pub use poseidon2::Poseidon2;

Modules

poseidon2

bb-compatible Poseidon2 (matches noir’s in-circuit poseidon2). A Poseidon2 hash generic over the prime field, with BN254 built in and bit-identical to what noir computes in-circuit: Poseidon2::permutation matches bn254_blackbox_solver::poseidon2 (the Poseidon2Permutation blackbox), and the PoseidonHasher sponge matches std::hash::poseidon2 (iv = len << 64 in the capacity, absorb in RATE blocks, a final permutation, squeeze state[0]).

Structs

Poseidon

A stateful sponge performing Poseidon hash computation.

PoseidonParameters

Parameters for the Poseidon hash algorithm.

Enums

PoseidonError

Constants

HASH_LEN

MAX_X5_LEN

Traits

PoseidonHasher