1use super::group::{GroupElement, GroupElementAffine, VartimeMultiscalarMul, GROUP_BASEPOINT};
 2use super::scalar::Scalar;
 3use crate::group::CompressGroupElement;
 4use crate::parameters::*;
 5use ark_ec::{AffineCurve, ProjectiveCurve};
 6use ark_ff::PrimeField;
 7
 8use ark_sponge::poseidon::PoseidonSponge;
 9use ark_sponge::CryptographicSponge;
10
11#[derive(Debug, Clone)]
12pub struct MultiCommitGens {
13    pub n: usize,
14    pub G: Vec<GroupElement>,
15    pub h: GroupElement,
16}
17
18impl MultiCommitGens {
19    pub fn new(n: usize, label: &[u8]) -> Self {
20        let params = poseidon_params();
21        let mut sponge = PoseidonSponge::new(&params);
22        sponge.absorb(&label);
23        sponge.absorb(&GROUP_BASEPOINT.compress().0);
24
25        let mut gens: Vec<GroupElement> = Vec::new();
26        for _ in 0..n + 1 {
27            let mut el_aff: Option<GroupElementAffine> = None;
28            while el_aff.is_none() {
29                let uniform_bytes = sponge.squeeze_bytes(64);
30                el_aff = GroupElementAffine::from_random_bytes(&uniform_bytes);
31            }
32            let el = el_aff.unwrap().mul_by_cofactor_to_projective();
33            gens.push(el);
34        }
35
36        MultiCommitGens {
37            n,
38            G: gens[..n].to_vec(),
39            h: gens[n],
40        }
41    }
42
43    pub fn clone(&self) -> MultiCommitGens {
44        MultiCommitGens {
45            n: self.n,
46            h: self.h,
47            G: self.G.clone(),
48        }
49    }
50
51    pub fn split_at(&self, mid: usize) -> (MultiCommitGens, MultiCommitGens) {
52        let (G1, G2) = self.G.split_at(mid);
53
54        (
55            MultiCommitGens {
56                n: G1.len(),
57                G: G1.to_vec(),
58                h: self.h,
59            },
60            MultiCommitGens {
61                n: G2.len(),
62                G: G2.to_vec(),
63                h: self.h,
64            },
65        )
66    }
67}
68
69pub trait Commitments {
70    fn commit(&self, blind: &Scalar, gens_n: &MultiCommitGens) -> GroupElement;
71}
72
73impl Commitments for Scalar {
74    fn commit(&self, blind: &Scalar, gens_n: &MultiCommitGens) -> GroupElement {
75        assert_eq!(gens_n.n, 1);
76        GroupElement::vartime_multiscalar_mul(&[*self, *blind], &[gens_n.G[0], gens_n.h])
77    }
78}
79
80impl Commitments for Vec<Scalar> {
81    fn commit(&self, blind: &Scalar, gens_n: &MultiCommitGens) -> GroupElement {
82        assert_eq!(gens_n.n, self.len());
83        GroupElement::vartime_multiscalar_mul(self, &gens_n.G) + gens_n.h.mul(blind.into_repr())
84    }
85}
86
87impl Commitments for [Scalar] {
88    fn commit(&self, blind: &Scalar, gens_n: &MultiCommitGens) -> GroupElement {
89        assert_eq!(gens_n.n, self.len());
90        GroupElement::vartime_multiscalar_mul(self, &gens_n.G) + gens_n.h.mul(blind.into_repr())
91    }
92}