Crate lib_q_poseidon 

Poseidon hash function optimized for zero-knowledge proofs

This crate provides a field-native implementation of the Poseidon hash function, specifically optimized for use in STARK proof systems with Complex<Mersenne31>.

Design

Poseidon is an algebraic hash function designed for efficient implementation in zero-knowledge proof systems. Unlike traditional hashes like SHA-3, Poseidon operates directly on field elements, making it orders of magnitude more efficient in circuit constraints.

Security

• Uses conservative round counts based on peer-reviewed research
• MDS matrices generated using secure methods
• Parameters chosen for 128-bit and 256-bit security levels

Example

use lib_q_poseidon::{Poseidon, Poseidon128};
use lib_q_stark_field::extension::Complex;
use lib_q_stark_mersenne31::Mersenne31;

type Val = Complex<Mersenne31>;

let hasher = Poseidon128::permutation();
let input = vec![Val::from(1u32), Val::from(2u32)];
let hash = hasher.hash(&input);

Structs

Poseidon128

Poseidon-128 parameters for 128-bit security over Complex<Mersenne31>

Poseidon256

Poseidon-256 parameters for 256-bit security over Complex<Mersenne31>

PoseidonParams

Poseidon parameter configuration

PoseidonPermutation

Poseidon permutation function

PoseidonSponge

Poseidon sponge in the absorb phase (before padding).

PoseidonSpongeSqueeze

Poseidon sponge after padding: squeeze output only.

Enums

PoseidonError

Error types for Poseidon operations

Traits

Poseidon

High-level Poseidon hash interface

Functions

mds_matrix_5x5

MDS matrix for state width 5 (Poseidon-128 over Complex<Mersenne31>). Cauchy construction so every square submatrix has nonzero determinant.

mds_matrix_7x7

MDS matrix for state width 7 (Poseidon-256 over Complex<Mersenne31>).

round_constants_128

Round constants for Poseidon-128 (64 rounds total: 8 full + 56 partial) State width 5 for 128-bit security over Complex<Mersenne31> (capacity 3 × ~62 bits ≥ 128).

round_constants_256

Round constants for Poseidon-256 (68 rounds total: 8 full + 60 partial) State width 7 for 256-bit security over Complex<Mersenne31> (capacity 5 × ~62 bits ≥ 256).

sbox

S-box function: x^5

Type Aliases

PoseidonField

Field type used for Poseidon

PoseidonState

Poseidon permutation state (variable length: state_width elements)