1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131

// Copyright (C) 2019-2021 Aleo Systems Inc.
// This file is part of the snarkVM library.

// The snarkVM library is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// The snarkVM library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with the snarkVM library. If not, see <https://www.gnu.org/licenses/>.

use crate::crh::{PedersenCRHParameters, PedersenSize};
use snarkvm_errors::{algorithms::CRHError, curves::ConstraintFieldError};
use snarkvm_models::{
    algorithms::{CRHParameters, CRH},
    curves::{to_field_vec::ToConstraintField, Field, Group},
};
use snarkvm_utilities::bytes_to_bits;

use rand::Rng;

#[cfg(feature = "pedersen-parallel")]
use rayon::prelude::*;

#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
pub struct PedersenCRH<G: Group, S: PedersenSize> {
    pub parameters: PedersenCRHParameters<G, S>,
}

impl<G: Group, S: PedersenSize> CRH for PedersenCRH<G, S> {
    type Output = G;
    type Parameters = PedersenCRHParameters<G, S>;

    const INPUT_SIZE_BITS: usize = S::WINDOW_SIZE * S::NUM_WINDOWS;

    fn setup<R: Rng>(rng: &mut R) -> Self {
        Self {
            parameters: PedersenCRHParameters::setup(rng),
        }
    }

    fn hash(&self, input: &[u8]) -> Result<Self::Output, CRHError> {
        if (input.len() * 8) > S::WINDOW_SIZE * S::NUM_WINDOWS {
            return Err(CRHError::IncorrectInputLength(
                input.len(),
                S::WINDOW_SIZE,
                S::NUM_WINDOWS,
            ));
        }

        // Pad the input if it is not the current length.
        let mut input = input;
        let mut padded_input = vec![];
        if (input.len() * 8) < S::WINDOW_SIZE * S::NUM_WINDOWS {
            padded_input.extend_from_slice(input);
            padded_input.resize((S::WINDOW_SIZE * S::NUM_WINDOWS) / 8, 0u8);
            input = padded_input.as_slice();
        }

        if self.parameters.bases.len() != S::NUM_WINDOWS {
            return Err(CRHError::IncorrectParameterSize(
                self.parameters.bases[0].len(),
                self.parameters.bases.len(),
                S::WINDOW_SIZE,
                S::NUM_WINDOWS,
            ));
        }

        // Compute sum of h_i^{m_i} for all i.
        let result = {
            #[cfg(feature = "pedersen-parallel")]
            {
                bytes_to_bits(input)
                    .collect::<Vec<_>>()
                    .par_chunks(S::WINDOW_SIZE)
                    .zip(&self.parameters.bases)
                    .map(|(bits, powers)| {
                        let mut encoded = G::zero();
                        for (bit, base) in bits.iter().zip(powers.iter()) {
                            if *bit {
                                encoded += base;
                            }
                        }
                        encoded
                    })
                    .reduce(G::zero, |a, b| a + &b)
            }
            #[cfg(not(feature = "pedersen-parallel"))]
            {
                bytes_to_bits(input)
                    .collect::<Vec<_>>()
                    .chunks(S::WINDOW_SIZE)
                    .zip(&self.parameters.bases)
                    .map(|(bits, powers)| {
                        let mut encoded = G::zero();
                        for (bit, base) in bits.iter().zip(powers.iter()) {
                            if *bit {
                                encoded += base;
                            }
                        }
                        encoded
                    })
                    .fold(G::zero(), |a, b| a + &b)
            }
        };

        Ok(result)
    }

    fn parameters(&self) -> &Self::Parameters {
        &self.parameters
    }
}

impl<G: Group, S: PedersenSize> From<PedersenCRHParameters<G, S>> for PedersenCRH<G, S> {
    fn from(parameters: PedersenCRHParameters<G, S>) -> Self {
        Self { parameters }
    }
}

impl<F: Field, G: Group + ToConstraintField<F>, S: PedersenSize> ToConstraintField<F> for PedersenCRH<G, S> {
    #[inline]
    fn to_field_elements(&self) -> Result<Vec<F>, ConstraintFieldError> {
        self.parameters.to_field_elements()
    }
}