snarkvm_console_algorithms/bhp/
hash_uncompressed.rs

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
132
133
// Copyright 2024 Aleo Network Foundation
// This file is part of the snarkVM library.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:

// http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use super::*;

impl<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> HashUncompressed
    for BHP<E, NUM_WINDOWS, WINDOW_SIZE>
{
    type Input = bool;
    type Output = Group<E>;

    /// Returns the BHP hash of the given input as an affine group element.
    ///
    /// This uncompressed variant of the BHP hash function is provided to support
    /// the BHP commitment scheme, as it is typically not used by applications.
    fn hash_uncompressed(&self, input: &[Self::Input]) -> Result<Self::Output> {
        // The number of hasher bits to fit.
        let num_hasher_bits = NUM_WINDOWS as usize * WINDOW_SIZE as usize * BHP_CHUNK_SIZE;
        // The number of data bits in the output.
        let num_data_bits = Field::<E>::size_in_data_bits();
        // The maximum number of input bits per iteration.
        let max_input_bits_per_iteration = num_hasher_bits - num_data_bits;

        debug_assert!(num_data_bits < num_hasher_bits);
        debug_assert_eq!(num_data_bits - 64, self.domain.len());

        // Initialize a variable to store the hash from the current iteration.
        let mut digest = Group::<E>::zero();

        // Prepare a reusable vector for the preimage.
        let mut preimage = Vec::with_capacity(num_hasher_bits);

        // Compute the hash of the input.
        for (i, input_bits) in input.chunks(max_input_bits_per_iteration).enumerate() {
            // Determine if this is the first iteration.
            match i == 0 {
                // Construct the first iteration as: [ 0...0 || DOMAIN || LENGTH(INPUT) || INPUT[0..BLOCK_SIZE] ].
                true => {
                    // Initialize a vector for the hash preimage.
                    preimage.extend(&self.domain);
                    (input.len() as u64).write_bits_le(&mut preimage);
                    preimage.extend(input_bits);
                }
                // Construct the subsequent iterations as: [ PREVIOUS_HASH[0..DATA_BITS] || INPUT[I * BLOCK_SIZE..(I + 1) * BLOCK_SIZE] ].
                false => {
                    // Initialize a vector for the hash preimage.
                    digest.to_x_coordinate().write_bits_le(&mut preimage);
                    preimage.truncate(num_data_bits);
                    preimage.extend(input_bits);
                }
            }
            // Hash the preimage for this iteration.
            digest = self.hasher.hash_uncompressed(&preimage)?;
            preimage.clear();
        }

        Ok(digest)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use snarkvm_console_types::environment::Console;

    type CurrentEnvironment = Console;

    const ITERATIONS: u64 = 1000;

    #[test]
    fn test_bhp256_input_size() -> Result<()> {
        let bhp = BHP256::<CurrentEnvironment>::setup("BHPTest")?;

        let mut rng = TestRng::default();

        for i in 0..ITERATIONS {
            let input = (0..bhp.window_size() as u64 + i).map(|_| bool::rand(&mut rng)).collect::<Vec<_>>();
            bhp.hash_uncompressed(&input)?;
        }
        Ok(())
    }

    #[test]
    fn test_bhp512_input_size() -> Result<()> {
        let bhp = BHP512::<CurrentEnvironment>::setup("BHPTest")?;

        let mut rng = TestRng::default();

        for i in 0..ITERATIONS {
            let input = (0..bhp.window_size() as u64 + i).map(|_| bool::rand(&mut rng)).collect::<Vec<_>>();
            bhp.hash_uncompressed(&input)?;
        }
        Ok(())
    }

    #[test]
    fn test_bhp768_input_size() -> Result<()> {
        let bhp = BHP768::<CurrentEnvironment>::setup("BHPTest")?;

        let mut rng = TestRng::default();

        for i in 0..ITERATIONS {
            let input = (0..bhp.window_size() as u64 + i).map(|_| bool::rand(&mut rng)).collect::<Vec<_>>();
            bhp.hash_uncompressed(&input)?;
        }
        Ok(())
    }

    #[test]
    fn test_bhp1024_input_size() -> Result<()> {
        let bhp = BHP1024::<CurrentEnvironment>::setup("BHPTest")?;

        let mut rng = TestRng::default();

        for i in 0..ITERATIONS {
            let input = (0..bhp.window_size() as u64 + i).map(|_| bool::rand(&mut rng)).collect::<Vec<_>>();
            bhp.hash_uncompressed(&input)?;
        }
        Ok(())
    }
}