snarkvm_circuit_algorithms/poseidon/
hash_to_group.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
// 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 RATE: usize> HashToGroup for Poseidon<E, RATE> {
    type Group = Group<E>;
    type Input = Field<E>;
    type Scalar = Scalar<E>;

    /// Returns an affine group element from hashing the input.
    #[inline]
    fn hash_to_group(&self, input: &[Self::Input]) -> Self::Group {
        // Ensure that the input is not empty.
        if input.is_empty() {
            E::halt("Input to hash to group cannot be empty")
        }
        // Compute `HashMany(input, 2)`.
        match self.hash_many(input, 2).iter().collect_tuple() {
            // Compute the group element as `MapToGroup(h0) + MapToGroup(h1)`.
            Some((h0, h1)) => Elligator2::encode(h1) + Elligator2::encode(h0),
            None => E::halt("Failed to compute the hash to group"),
        }
    }
}

#[cfg(all(test, feature = "console"))]
mod tests {
    use super::*;
    use snarkvm_circuit_types::environment::Circuit;
    use snarkvm_curves::{AffineCurve, ProjectiveCurve};

    use anyhow::Result;

    const ITERATIONS: u64 = 100;
    const DOMAIN: &str = "PoseidonCircuit0";

    macro_rules! check_hash_to_group {
        ($poseidon:ident, $mode:ident, $num_fields:expr, ($num_constants:expr, $num_public:expr, $num_private:expr, $num_constraints:expr)) => {{
            // Initialize Poseidon.
            let native = console::$poseidon::<<Circuit as Environment>::Network>::setup(DOMAIN)?;
            let circuit = $poseidon::<Circuit>::constant(native.clone());

            let rng = &mut TestRng::default();

            for i in 0..ITERATIONS {
                // Sample a random input.
                let input = (0..$num_fields).map(|_| Uniform::rand(rng)).collect::<Vec<_>>();
                // Compute the expected hash.
                let expected = console::HashToGroup::hash_to_group(&native, &input)?;
                // Prepare the circuit input.
                let circuit_input: Vec<Field<_>> = Inject::new(Mode::$mode, input);

                Circuit::scope(format!("Poseidon HashToGroup {i}"), || {
                    // Perform the hash operation.
                    let candidate = circuit.hash_to_group(&circuit_input);
                    assert_scope!($num_constants, $num_public, $num_private, $num_constraints);
                    assert_eq!(expected, candidate.eject_value());

                    // Eject the value to inspect it further.
                    let candidate = candidate.eject_value();
                    assert!((*candidate).to_affine().is_on_curve());
                    assert!((*candidate).to_affine().is_in_correct_subgroup_assuming_on_curve());
                    assert_ne!(console::Group::<<Circuit as Environment>::Network>::zero(), candidate);
                    assert_ne!(console::Group::<<Circuit as Environment>::Network>::generator(), candidate);

                    let candidate_cofactor_inv = candidate.div_by_cofactor();
                    assert_eq!(candidate, candidate_cofactor_inv.mul_by_cofactor());
                });
                Circuit::reset();
            }
            Ok::<_, anyhow::Error>(())
        }};
    }

    #[test]
    fn test_poseidon2_hash_to_group_constant() -> Result<()> {
        check_hash_to_group!(Poseidon2, Constant, 2, (1059, 0, 0, 0))
    }

    #[test]
    fn test_poseidon2_hash_to_group_public() -> Result<()> {
        check_hash_to_group!(Poseidon2, Public, 2, (529, 0, 2026, 2036))
    }

    #[test]
    fn test_poseidon2_hash_to_group_private() -> Result<()> {
        check_hash_to_group!(Poseidon2, Private, 2, (529, 0, 2026, 2036))
    }

    #[test]
    fn test_poseidon4_hash_to_group_constant() -> Result<()> {
        check_hash_to_group!(Poseidon4, Constant, 2, (1059, 0, 0, 0))
    }

    #[test]
    fn test_poseidon4_hash_to_group_public() -> Result<()> {
        check_hash_to_group!(Poseidon4, Public, 2, (529, 0, 2096, 2106))
    }

    #[test]
    fn test_poseidon4_hash_to_group_private() -> Result<()> {
        check_hash_to_group!(Poseidon4, Private, 2, (529, 0, 2096, 2106))
    }

    #[test]
    fn test_poseidon8_hash_to_group_constant() -> Result<()> {
        check_hash_to_group!(Poseidon8, Constant, 2, (1059, 0, 0, 0))
    }

    #[test]
    fn test_poseidon8_hash_to_group_public() -> Result<()> {
        check_hash_to_group!(Poseidon8, Public, 2, (529, 0, 2236, 2246))
    }

    #[test]
    fn test_poseidon8_hash_to_group_private() -> Result<()> {
        check_hash_to_group!(Poseidon8, Private, 2, (529, 0, 2236, 2246))
    }
}