snarkvm_console_algorithms/bhp/
hash_uncompressed.rs

1// Copyright (c) 2019-2025 Provable Inc.
2// This file is part of the snarkVM library.
3
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at:
7
8// http://www.apache.org/licenses/LICENSE-2.0
9
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15
16use super::*;
17
18impl<E: Environment, const NUM_WINDOWS: u8, const WINDOW_SIZE: u8> HashUncompressed
19    for BHP<E, NUM_WINDOWS, WINDOW_SIZE>
20{
21    type Input = bool;
22    type Output = Group<E>;
23
24    /// Returns the BHP hash of the given input as an affine group element.
25    ///
26    /// This uncompressed variant of the BHP hash function is provided to support
27    /// the BHP commitment scheme, as it is typically not used by applications.
28    fn hash_uncompressed(&self, input: &[Self::Input]) -> Result<Self::Output> {
29        // The number of hasher bits to fit.
30        let num_hasher_bits = NUM_WINDOWS as usize * WINDOW_SIZE as usize * BHP_CHUNK_SIZE;
31        // The number of data bits in the output.
32        let num_data_bits = Field::<E>::size_in_data_bits();
33        // The maximum number of input bits per iteration.
34        let max_input_bits_per_iteration = num_hasher_bits - num_data_bits;
35
36        debug_assert!(num_data_bits < num_hasher_bits);
37        debug_assert_eq!(num_data_bits - 64, self.domain.len());
38
39        // Initialize a variable to store the hash from the current iteration.
40        let mut digest = Group::<E>::zero();
41
42        // Prepare a reusable vector for the preimage.
43        let mut preimage = Vec::with_capacity(num_hasher_bits);
44
45        // Compute the hash of the input.
46        for (i, input_bits) in input.chunks(max_input_bits_per_iteration).enumerate() {
47            // Determine if this is the first iteration.
48            match i == 0 {
49                // Construct the first iteration as: [ 0...0 || DOMAIN || LENGTH(INPUT) || INPUT[0..BLOCK_SIZE] ].
50                true => {
51                    // Initialize a vector for the hash preimage.
52                    preimage.extend(&self.domain);
53                    (input.len() as u64).write_bits_le(&mut preimage);
54                    preimage.extend(input_bits);
55                }
56                // Construct the subsequent iterations as: [ PREVIOUS_HASH[0..DATA_BITS] || INPUT[I * BLOCK_SIZE..(I + 1) * BLOCK_SIZE] ].
57                false => {
58                    // Initialize a vector for the hash preimage.
59                    digest.to_x_coordinate().write_bits_le(&mut preimage);
60                    preimage.truncate(num_data_bits);
61                    preimage.extend(input_bits);
62                }
63            }
64            // Hash the preimage for this iteration.
65            digest = self.hasher.hash_uncompressed(&preimage)?;
66            preimage.clear();
67        }
68
69        Ok(digest)
70    }
71}
72
73#[cfg(test)]
74mod tests {
75    use super::*;
76    use snarkvm_console_types::environment::Console;
77
78    type CurrentEnvironment = Console;
79
80    const ITERATIONS: u64 = 1000;
81
82    #[test]
83    fn test_bhp256_input_size() -> Result<()> {
84        let bhp = BHP256::<CurrentEnvironment>::setup("BHPTest")?;
85
86        let mut rng = TestRng::default();
87
88        for i in 0..ITERATIONS {
89            let input = (0..bhp.window_size() as u64 + i).map(|_| bool::rand(&mut rng)).collect::<Vec<_>>();
90            bhp.hash_uncompressed(&input)?;
91        }
92        Ok(())
93    }
94
95    #[test]
96    fn test_bhp512_input_size() -> Result<()> {
97        let bhp = BHP512::<CurrentEnvironment>::setup("BHPTest")?;
98
99        let mut rng = TestRng::default();
100
101        for i in 0..ITERATIONS {
102            let input = (0..bhp.window_size() as u64 + i).map(|_| bool::rand(&mut rng)).collect::<Vec<_>>();
103            bhp.hash_uncompressed(&input)?;
104        }
105        Ok(())
106    }
107
108    #[test]
109    fn test_bhp768_input_size() -> Result<()> {
110        let bhp = BHP768::<CurrentEnvironment>::setup("BHPTest")?;
111
112        let mut rng = TestRng::default();
113
114        for i in 0..ITERATIONS {
115            let input = (0..bhp.window_size() as u64 + i).map(|_| bool::rand(&mut rng)).collect::<Vec<_>>();
116            bhp.hash_uncompressed(&input)?;
117        }
118        Ok(())
119    }
120
121    #[test]
122    fn test_bhp1024_input_size() -> Result<()> {
123        let bhp = BHP1024::<CurrentEnvironment>::setup("BHPTest")?;
124
125        let mut rng = TestRng::default();
126
127        for i in 0..ITERATIONS {
128            let input = (0..bhp.window_size() as u64 + i).map(|_| bool::rand(&mut rng)).collect::<Vec<_>>();
129            bhp.hash_uncompressed(&input)?;
130        }
131        Ok(())
132    }
133}
snarkvm_console_algorithms/bhp/hash_uncompressed.rs

snarkvm_console_algorithms/bhp/
hash_uncompressed.rs
