Crate dusk_hades

Expand description

Hades252

Implementation of Hades252 permutation algorithm over the Bls12-381 Scalar field.

Documentation

To generate the Hades252 documentation:

make doc
make doc-internal

Use

To import Hades252, add the following to the dependencies section of your project’s Cargo.toml:

dusk-hades = "0.16.0"

Hades252 has a width equals to 5; it’s possible to use a different value, see How to generate the assets.

Parameters

p = 0x73eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000001
Security level is 117 -120 bits of security [NCCG] bits.
width = 5
Number of full rounds = 8 . There are four full rounds at the beginning and four full rounds at the end, where each full round has WIDTH quintic S-Boxes.
Number of partial rounds = 59, where each partial round has one quintic S-Box and (width-1) identity functions.
Number of round constants = 960

Example for `ScalarStrategy`

use dusk_bls12_381::BlsScalar;
use dusk_hades::{ScalarStrategy, Strategy, WIDTH};

// Generate the inputs that will permute.
// The number of values we can input is equivalent to `WIDTH`

let input = vec![BlsScalar::from(1u64); dusk_hades::WIDTH];
let mut output = input.clone();

let mut strategy = ScalarStrategy::new();
strategy.perm(output.as_mut_slice());

assert_ne!(&input, &output);
assert_eq!(input.len(), output.len());

Example for `GadgetStrategy`

// Proving that we know the pre-image of a hades-252 hash.
use dusk_hades::{GadgetStrategy, Strategy, WIDTH};
use dusk_plonk::prelude::*;

// Setup OG params.
const CAPACITY: usize = 1 << 10;

let public_parameters = PublicParameters::setup(CAPACITY, &mut rand::thread_rng()).unwrap();
let (ck, vk) = public_parameters.trim(CAPACITY).unwrap();;

// Gen inputs
let mut inputs = [BlsScalar::one(); WIDTH];

let mut prover = Prover::new(b"Hades_Testing");

// Generate the witness data
let mut composer = prover.composer_mut();
let zero = TurboComposer::constant_zero();

let mut witness = [zero; WIDTH];
witness.iter_mut()
    .zip(inputs.iter())
    .for_each(|(w, i)| *w = composer.append_witness(*i));

// Perform the permutation in the circuit
GadgetStrategy::gadget(prover.composer_mut(), &mut witness);

// Now your composer has been filled with a hades permutation
// inside.
// Now you can build your proof or keep extending your circuit.

Deviations

Round constants for the full rounds are generated following: https://extgit.iaik.tugraz.at/krypto/hadesmimc/blob/master/code/calc_round_numbers.py
The MDS matrix is a cauchy matrix, the method used to generate it, is noted in section “Concrete Instantiations Poseidon and Starkad”

Reference

https://eprint.iacr.org/2019/458.pdf

Structs

ScalarStrategy

Implements a Hades252 strategy for BlsScalar as input values.

Constants

PARTIAL_ROUNDS

Total ammount of partial rounds that will be applied. This is expressed as Rp in the paper.

TOTAL_FULL_ROUNDS

Total ammount of full rounds that will be applied. This is expressed as RF in the paper.

WIDTH

Maximum input width for the rounds

Traits

Strategy

Defines the Hades252 strategy algorithm.