decaf377/fields/fr/u32/
wrapper.rs

1use super::{
2    super::{B, N_32, N_64, N_8},
3    fiat,
4};
5
6const N: usize = N_32;
7
8#[derive(Copy, Clone)]
9pub struct Fr(fiat::FrMontgomeryDomainFieldElement);
10
11impl PartialEq for Fr {
12    fn eq(&self, other: &Self) -> bool {
13        let sub = self.sub(other);
14        let mut check_word = 0;
15        fiat::fr_nonzero(&mut check_word, &sub.0 .0);
16        check_word == 0
17    }
18}
19
20impl Eq for Fr {}
21
22impl zeroize::Zeroize for Fr {
23    fn zeroize(&mut self) {
24        self.0 .0.zeroize()
25    }
26}
27
28impl Fr {
29    pub(crate) fn from_le_limbs(limbs: [u64; N_64]) -> Fr {
30        let limbs = {
31            let mut out = [0u32; N];
32            for i in 0..N_64 {
33                out[2 * i] = (limbs[i] & 0xFFFF_FFFF_FFFF_FFFF) as u32;
34                out[2 * i + 1] = (limbs[i] >> 32) as u32;
35            }
36            out
37        };
38        let x_non_monty = fiat::FrNonMontgomeryDomainFieldElement(limbs);
39        let mut x = fiat::FrMontgomeryDomainFieldElement([0; N]);
40        fiat::fr_to_montgomery(&mut x, &x_non_monty);
41        Self(x)
42    }
43
44    pub(crate) fn from_raw_bytes(bytes: &[u8; N_8]) -> Fr {
45        let mut x_non_montgomery = fiat::FrNonMontgomeryDomainFieldElement([0; N]);
46        let mut x = fiat::FrMontgomeryDomainFieldElement([0; N]);
47
48        fiat::fr_from_bytes(&mut x_non_montgomery.0, &bytes);
49        fiat::fr_to_montgomery(&mut x, &x_non_montgomery);
50
51        Self(x)
52    }
53
54    pub(crate) fn to_le_limbs(&self) -> [u64; N_64] {
55        let mut x_non_montgomery = fiat::FrNonMontgomeryDomainFieldElement([0; N]);
56        fiat::fr_from_montgomery(&mut x_non_montgomery, &self.0);
57        let limbs = x_non_montgomery.0;
58        let mut out = [0u64; N_64];
59        for i in 0..N_64 {
60            out[i] = (limbs[2 * i] as u64) | ((limbs[2 * i + 1] as u64) << 32);
61        }
62        out
63    }
64
65    pub fn to_bytes_le(&self) -> [u8; N_8] {
66        let mut bytes = [0u8; N_8];
67        let mut x_non_montgomery = fiat::FrNonMontgomeryDomainFieldElement([0; N]);
68        fiat::fr_from_montgomery(&mut x_non_montgomery, &self.0);
69        fiat::fr_to_bytes(&mut bytes, &x_non_montgomery.0);
70        bytes
71    }
72
73    const fn from_montgomery_limbs_backend(limbs: [u32; N]) -> Fr {
74        Self(fiat::FrMontgomeryDomainFieldElement(limbs))
75    }
76
77    pub(crate) const fn from_montgomery_limbs(limbs: [u64; N_64]) -> Fr {
78        Self::from_montgomery_limbs_backend([
79            limbs[0] as u32,
80            (limbs[0] >> 32) as u32,
81            limbs[1] as u32,
82            (limbs[1] >> 32) as u32,
83            limbs[2] as u32,
84            (limbs[2] >> 32) as u32,
85            limbs[3] as u32,
86            (limbs[3] >> 32) as u32,
87        ])
88    }
89
90    pub const ZERO: Fr = Self(fiat::FrMontgomeryDomainFieldElement([0; N]));
91
92    pub const ONE: Fr = Self(fiat::FrMontgomeryDomainFieldElement([
93        3498574902, 3872500570, 2604314180, 2497411308, 588265454, 3867012838, 3735373809, 66463618,
94    ]));
95
96    pub fn square(&self) -> Fr {
97        let mut result = fiat::FrMontgomeryDomainFieldElement([0; N]);
98        fiat::fr_square(&mut result, &self.0);
99        Self(result)
100    }
101
102    pub fn inverse(&self) -> Option<Self> {
103        if self == &Self::ZERO {
104            return None;
105        }
106
107        const I: usize = (49 * B + 57) / 17;
108
109        let mut a = fiat::FrNonMontgomeryDomainFieldElement([0; N]);
110        fiat::fr_from_montgomery(&mut a, &self.0);
111        let mut d = 1;
112        let mut f: [u32; N + 1] = [0u32; N + 1];
113        fiat::fr_msat(&mut f);
114        let mut g: [u32; N + 1] = [0u32; N + 1];
115        let mut v: [u32; N] = [0u32; N];
116        let mut r: [u32; N] = Self::ONE.0 .0;
117        let mut i = 0;
118        let mut j = 0;
119
120        while j < N {
121            g[j] = a[j];
122            j += 1;
123        }
124
125        let mut out1: u32 = 0;
126        let mut out2: [u32; N + 1] = [0; N + 1];
127        let mut out3: [u32; N + 1] = [0; N + 1];
128        let mut out4: [u32; N] = [0; N];
129        let mut out5: [u32; N] = [0; N];
130        let mut out6: u32 = 0;
131        let mut out7: [u32; N + 1] = [0; N + 1];
132        let mut out8: [u32; N + 1] = [0; N + 1];
133        let mut out9: [u32; N] = [0; N];
134        let mut out10: [u32; N] = [0; N];
135
136        while i < I - I % 2 {
137            fiat::fr_divstep(
138                &mut out1, &mut out2, &mut out3, &mut out4, &mut out5, d, &f, &g, &v, &r,
139            );
140            fiat::fr_divstep(
141                &mut out6, &mut out7, &mut out8, &mut out9, &mut out10, out1, &out2, &out3, &out4,
142                &out5,
143            );
144            d = out6;
145            f = out7;
146            g = out8;
147            v = out9;
148            r = out10;
149            i += 2;
150        }
151
152        if I % 2 != 0 {
153            fiat::fr_divstep(
154                &mut out1, &mut out2, &mut out3, &mut out4, &mut out5, d, &f, &g, &v, &r,
155            );
156            v = out4;
157            f = out2;
158        }
159
160        let s = ((f[f.len() - 1] >> (32 - 1)) & 1) as u8;
161        let mut neg = fiat::FrMontgomeryDomainFieldElement([0; N]);
162        fiat::fr_opp(&mut neg, &fiat::FrMontgomeryDomainFieldElement(v));
163
164        let mut v_prime: [u32; N] = [0u32; N];
165        fiat::fr_selectznz(&mut v_prime, s, &v, &neg.0);
166
167        let mut pre_comp: [u32; N] = [0u32; N];
168        fiat::fr_divstep_precomp(&mut pre_comp);
169
170        let mut result = fiat::FrMontgomeryDomainFieldElement([0; N]);
171        fiat::fr_mul(
172            &mut result,
173            &fiat::FrMontgomeryDomainFieldElement(v_prime),
174            &fiat::FrMontgomeryDomainFieldElement(pre_comp),
175        );
176
177        Some(Fr(result))
178    }
179
180    pub fn add(self, other: &Fr) -> Fr {
181        let mut result = fiat::FrMontgomeryDomainFieldElement([0; N]);
182        fiat::fr_add(&mut result, &self.0, &other.0);
183        Fr(result)
184    }
185
186    pub fn sub(self, other: &Fr) -> Fr {
187        let mut result = fiat::FrMontgomeryDomainFieldElement([0; N]);
188        fiat::fr_sub(&mut result, &self.0, &other.0);
189        Fr(result)
190    }
191
192    pub fn mul(self, other: &Fr) -> Fr {
193        let mut result = fiat::FrMontgomeryDomainFieldElement([0; N]);
194        fiat::fr_mul(&mut result, &self.0, &other.0);
195        Fr(result)
196    }
197
198    pub fn neg(self) -> Fr {
199        let mut result = fiat::FrMontgomeryDomainFieldElement([0; N]);
200        fiat::fr_opp(&mut result, &self.0);
201        Fr(result)
202    }
203}
decaf377/fields/fr/u32/wrapper.rs

decaf377/fields/fr/u32/
wrapper.rs
