ark_ff/fields/models/
fp4.rs

1use super::quadratic_extension::{QuadExtConfig, QuadExtField};
2use crate::{
3    fields::{Fp2, Fp2Config},
4    CyclotomicMultSubgroup, Zero,
5};
6use core::{marker::PhantomData, ops::Not};
7
8pub trait Fp4Config: 'static + Send + Sync {
9    type Fp2Config: Fp2Config;
10
11    /// This *must* equal (0, 1);
12    /// see [[DESD06, Section 5.1]](https://eprint.iacr.org/2006/471.pdf).
13    const NONRESIDUE: Fp2<Self::Fp2Config>;
14
15    /// Coefficients for the Frobenius automorphism.
16    /// non_residue^((modulus^i-1)/4) for i=0,1,2,3
17    const FROBENIUS_COEFF_FP4_C1: &'static [<Self::Fp2Config as Fp2Config>::Fp];
18
19    #[inline(always)]
20    fn mul_fp2_by_nonresidue_in_place(fe: &mut Fp2<Self::Fp2Config>) -> &mut Fp2<Self::Fp2Config> {
21        // see [[DESD06, Section 5.1]](https://eprint.iacr.org/2006/471.pdf).
22        let new_c1 = fe.c0;
23        Self::Fp2Config::mul_fp_by_nonresidue_in_place(&mut fe.c1);
24        fe.c0 = fe.c1;
25        fe.c1 = new_c1;
26        fe
27    }
28}
29
30pub struct Fp4ConfigWrapper<P: Fp4Config>(PhantomData<P>);
31
32impl<P: Fp4Config> QuadExtConfig for Fp4ConfigWrapper<P> {
33    type BasePrimeField = <P::Fp2Config as Fp2Config>::Fp;
34    type BaseField = Fp2<P::Fp2Config>;
35    type FrobCoeff = Self::BasePrimeField;
36
37    const DEGREE_OVER_BASE_PRIME_FIELD: usize = 4;
38
39    const NONRESIDUE: Self::BaseField = P::NONRESIDUE;
40
41    const FROBENIUS_COEFF_C1: &'static [Self::FrobCoeff] = P::FROBENIUS_COEFF_FP4_C1;
42
43    #[inline(always)]
44    fn mul_base_field_by_nonresidue_in_place(fe: &mut Self::BaseField) -> &mut Self::BaseField {
45        P::mul_fp2_by_nonresidue_in_place(fe)
46    }
47
48    fn mul_base_field_by_frob_coeff(fe: &mut Self::BaseField, power: usize) {
49        fe.mul_assign_by_fp(&Self::FROBENIUS_COEFF_C1[power % Self::DEGREE_OVER_BASE_PRIME_FIELD]);
50    }
51}
52
53pub type Fp4<P> = QuadExtField<Fp4ConfigWrapper<P>>;
54
55impl<P: Fp4Config> Fp4<P> {
56    pub fn mul_by_fp(&mut self, element: &<P::Fp2Config as Fp2Config>::Fp) {
57        self.c0.mul_assign_by_fp(element);
58        self.c1.mul_assign_by_fp(element);
59    }
60
61    pub fn mul_by_fp2(&mut self, element: &Fp2<P::Fp2Config>) {
62        self.c0 *= element;
63        self.c1 *= element;
64    }
65}
66
67impl<P: Fp4Config> CyclotomicMultSubgroup for Fp4<P> {
68    const INVERSE_IS_FAST: bool = true;
69    fn cyclotomic_inverse_in_place(&mut self) -> Option<&mut Self> {
70        self.is_zero().not().then(|| {
71            self.conjugate_in_place();
72            self
73        })
74    }
75}
ark_ff/fields/models/fp4.rs

ark_ff/fields/models/
fp4.rs
