Poseidon2

Overview

This is Starkom's implementation of the Poseidon2 algebraic hash.

This crate uses version 2 of the permutation. For version 1 see the starkom-poseidon crate.

The implementation is generic and works on any prime field.

Configurations for the BLS12-381, Goldilocks, and BlueSky prime fields are provided; the BLS12-381 and BlueSky configurations support T=3 and T=4, while the Goldilocks configurations support T=12 and T=16.

[!NOTE] All predefined configurations are gated behind feature flags to avoid including all constants in all builds. The currently defined feature flags are bls12_381, goldilocks, and bluesky, all disabled by default.

Usage

The following example functions instantiate Poseidon2 with T=3 and T=4 respectively, squeezing a single element from the output. Both use a single element for capacity.

use starkom_bluesky::Scalar;
use starkom_poseidon2;

fn hash_t3(inputs: impl IntoIterator<Item = Scalar>) -> Scalar {
    starkom_poseidon2::hash::<starkom_poseidon2::bluesky::BlueSkyConfig3, Scalar, 3, 2, 1>(inputs)[0]
}

fn hash_t4(inputs: impl IntoIterator<Item = Scalar>) -> Scalar {
    starkom_poseidon2::hash::<starkom_poseidon2::bluesky::BlueSkyConfig4, Scalar, 4, 3, 1>(inputs)[0]
}