zkhash/poseidon2/
poseidon2_params.rs

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1use ark_ff::PrimeField;
2
3use crate::utils;
4
5#[derive(Clone, Debug)]
6pub struct Poseidon2Params<F: PrimeField> {
7    pub(crate) t: usize, // statesize
8    pub(crate) d: usize, // sbox degree
9    pub(crate) rounds_f_beginning: usize,
10    pub(crate) rounds_p: usize,
11    #[allow(dead_code)]
12    pub(crate) rounds_f_end: usize,
13    pub(crate) rounds: usize,
14    pub(crate) mat_internal_diag_m_1: Vec<F>,
15    pub(crate) _mat_internal: Vec<Vec<F>>,
16    pub(crate) round_constants: Vec<Vec<F>>,
17}
18
19impl<F: PrimeField> Poseidon2Params<F> {
20    #[allow(clippy::too_many_arguments)]
21
22    pub const INIT_SHAKE: &'static str = "Poseidon2";
23
24    pub fn new(
25        t: usize,
26        d: usize,
27        rounds_f: usize,
28        rounds_p: usize,
29        mat_internal_diag_m_1: &[F],
30        mat_internal: &[Vec<F>],
31        round_constants: &[Vec<F>],
32    ) -> Self {
33        assert!(d == 3 || d == 5 || d == 7 || d == 11);
34        assert_eq!(rounds_f % 2, 0);
35        let r = rounds_f / 2;
36        let rounds = rounds_f + rounds_p;
37
38        Poseidon2Params {
39            t,
40            d,
41            rounds_f_beginning: r,
42            rounds_p,
43            rounds_f_end: r,
44            rounds,
45            mat_internal_diag_m_1: mat_internal_diag_m_1.to_owned(),
46            _mat_internal: mat_internal.to_owned(),
47            round_constants: round_constants.to_owned(),
48        }
49    }
50
51    // Unused
52    pub fn equivalent_round_constants(
53        round_constants: &[Vec<F>],
54        mat_internal: &[Vec<F>],
55        rounds_f_beginning: usize,
56        rounds_p: usize,
57    ) -> Vec<Vec<F>> {
58        let mut opt = vec![Vec::new(); rounds_p + 1];
59        let mat_internal_inv = utils::mat_inverse(mat_internal);
60
61        let p_end = rounds_f_beginning + rounds_p - 1;
62        let mut tmp = round_constants[p_end].clone();
63        for i in (0..rounds_p - 1).rev() {
64            let inv_cip = Self::mat_vec_mul(&mat_internal_inv, &tmp);
65            opt[i + 1] = vec![inv_cip[0]];
66            tmp = round_constants[rounds_f_beginning + i].clone();
67            for i in 1..inv_cip.len() {
68                tmp[i].add_assign(&inv_cip[i]);
69            }
70        }
71        opt[0] = tmp;
72        opt[rounds_p] = vec![F::zero(); opt[0].len()]; // opt[0].len() = t
73
74        opt
75    }
76
77    pub fn mat_vec_mul(mat: &[Vec<F>], input: &[F]) -> Vec<F> {
78        let t = mat.len();
79        debug_assert!(t == input.len());
80        let mut out = vec![F::zero(); t];
81        for row in 0..t {
82            for (col, inp) in input.iter().enumerate() {
83                let mut tmp = mat[row][col];
84                tmp.mul_assign(inp);
85                out[row].add_assign(&tmp);
86            }
87        }
88        out
89    }
90
91}
zkhash/poseidon2/poseidon2_params.rs

zkhash/poseidon2/
poseidon2_params.rs
