1  // Copyright (c) 2019-2025 Alpha-Delta Network Inc.
 2  // This file is part of the deltavm 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  
16  use crate::traits::{AffineCurve, PairingCurve, ProjectiveCurve};
17  use deltavm_fields::{Field, PrimeField, SquareRootField, ToConstraintField};
18  
19  use core::{fmt::Debug, hash::Hash, iter};
20  
21  pub trait PairingEngine: Sized + 'static + Copy + Debug + PartialEq + Eq + Hash + Sync + Send {
22      /// This is the scalar field of the G1/G2 groups.
23      type Fr: PrimeField + SquareRootField + Into<<Self::Fr as PrimeField>::BigInteger>;
24  
25      /// The projective representation of an element in G1.
26      type G1Projective: ProjectiveCurve<BaseField = Self::Fq, ScalarField = Self::Fr, Affine = Self::G1Affine>
27          + From<Self::G1Affine>;
28  
29      /// The affine representation of an element in G1.
30      type G1Affine: AffineCurve<BaseField = Self::Fq, ScalarField = Self::Fr, Projective = Self::G1Projective>
31          + PairingCurve<PairWith = Self::G2Affine, PairingResult = Self::Fqk>
32          + From<Self::G1Projective>
33          + ToConstraintField<Self::Fq>;
34  
35      /// The projective representation of an element in G2.
36      type G2Projective: ProjectiveCurve<BaseField = Self::Fqe, ScalarField = Self::Fr, Affine = Self::G2Affine>
37          + From<Self::G2Affine>;
38  
39      /// The affine representation of an element in G2.
40      type G2Affine: AffineCurve<BaseField = Self::Fqe, ScalarField = Self::Fr, Projective = Self::G2Projective>
41          + PairingCurve<PairWith = Self::G1Affine, PairingResult = Self::Fqk>
42          + From<Self::G2Projective>
43          + ToConstraintField<Self::Fq>;
44  
45      /// The base field that hosts G1.
46      type Fq: PrimeField + SquareRootField;
47  
48      /// The extension field that hosts G2.
49      type Fqe: SquareRootField;
50  
51      /// The extension field that hosts the target group of the pairing.
52      type Fqk: Field;
53  
54      /// Perform a miller loop with some number of (G1, G2) pairs.
55      #[must_use]
56      fn miller_loop<'a, I>(i: I) -> Self::Fqk
57      where
58          I: Iterator<
59              Item = (&'a <Self::G1Affine as PairingCurve>::Prepared, &'a <Self::G2Affine as PairingCurve>::Prepared),
60          >;
61  
62      /// Perform final exponentiation of the result of a miller loop.
63      #[must_use]
64      fn final_exponentiation(_: &Self::Fqk) -> Option<Self::Fqk>;
65  
66      /// Computes a product of pairings.
67      #[must_use]
68      fn product_of_pairings<'a, I>(i: I) -> Self::Fqk
69      where
70          I: Iterator<
71              Item = (&'a <Self::G1Affine as PairingCurve>::Prepared, &'a <Self::G2Affine as PairingCurve>::Prepared),
72          >,
73      {
74          Self::final_exponentiation(&Self::miller_loop(i)).unwrap()
75      }
76  
77      /// Performs multiple pairing operations
78      #[must_use]
79      fn pairing<G1, G2>(p: G1, q: G2) -> Self::Fqk
80      where
81          G1: Into<Self::G1Affine>,
82          G2: Into<Self::G2Affine>,
83      {
84          Self::final_exponentiation(&Self::miller_loop(iter::once((&p.into().prepare(), &q.into().prepare())))).unwrap()
85      }
86  }