crypto_bigint/modular/fixed_monty_form/
add.rs

1//! Additions between integers in Montgomery form with a modulus set at runtime.
2
3use super::FixedMontyForm;
4use crate::modular::add::{add_montgomery_form, double_montgomery_form};
5use core::ops::{Add, AddAssign};
6
7impl<const LIMBS: usize> FixedMontyForm<LIMBS> {
8    /// Adds `rhs`.
9    #[must_use]
10    pub const fn add(&self, rhs: &Self) -> Self {
11        Self {
12            montgomery_form: add_montgomery_form(
13                &self.montgomery_form,
14                &rhs.montgomery_form,
15                &self.params.modulus,
16            ),
17            params: self.params,
18        }
19    }
20
21    /// Double `self`.
22    #[must_use]
23    pub const fn double(&self) -> Self {
24        Self {
25            montgomery_form: double_montgomery_form(&self.montgomery_form, &self.params.modulus),
26            params: self.params,
27        }
28    }
29}
30
31impl<const LIMBS: usize> Add<&FixedMontyForm<LIMBS>> for &FixedMontyForm<LIMBS> {
32    type Output = FixedMontyForm<LIMBS>;
33    fn add(self, rhs: &FixedMontyForm<LIMBS>) -> FixedMontyForm<LIMBS> {
34        debug_assert_eq!(self.params, rhs.params);
35        self.add(rhs)
36    }
37}
38
39impl<const LIMBS: usize> Add<FixedMontyForm<LIMBS>> for &FixedMontyForm<LIMBS> {
40    type Output = FixedMontyForm<LIMBS>;
41    #[allow(clippy::op_ref)]
42    fn add(self, rhs: FixedMontyForm<LIMBS>) -> FixedMontyForm<LIMBS> {
43        self + &rhs
44    }
45}
46
47impl<const LIMBS: usize> Add<&FixedMontyForm<LIMBS>> for FixedMontyForm<LIMBS> {
48    type Output = FixedMontyForm<LIMBS>;
49    #[allow(clippy::op_ref)]
50    fn add(self, rhs: &FixedMontyForm<LIMBS>) -> FixedMontyForm<LIMBS> {
51        &self + rhs
52    }
53}
54
55impl<const LIMBS: usize> Add<FixedMontyForm<LIMBS>> for FixedMontyForm<LIMBS> {
56    type Output = FixedMontyForm<LIMBS>;
57    fn add(self, rhs: FixedMontyForm<LIMBS>) -> FixedMontyForm<LIMBS> {
58        &self + &rhs
59    }
60}
61
62impl<const LIMBS: usize> AddAssign<&FixedMontyForm<LIMBS>> for FixedMontyForm<LIMBS> {
63    fn add_assign(&mut self, rhs: &FixedMontyForm<LIMBS>) {
64        *self = *self + rhs;
65    }
66}
67
68impl<const LIMBS: usize> AddAssign<FixedMontyForm<LIMBS>> for FixedMontyForm<LIMBS> {
69    fn add_assign(&mut self, rhs: FixedMontyForm<LIMBS>) {
70        *self += &rhs;
71    }
72}
73
74#[cfg(test)]
75mod tests {
76    use crate::{
77        Odd, U256,
78        modular::{FixedMontyForm, FixedMontyParams},
79    };
80
81    #[test]
82    fn add_overflow() {
83        let params = FixedMontyParams::new_vartime(Odd::<U256>::from_be_hex(
84            "ffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551",
85        ));
86
87        let x =
88            U256::from_be_hex("44acf6b7e36c1342c2c5897204fe09504e1e2efb1a900377dbc4e7a6a133ec56");
89        let mut x_mod = FixedMontyForm::new(&x, &params);
90
91        let y =
92            U256::from_be_hex("d5777c45019673125ad240f83094d4252d829516fac8601ed01979ec1ec1a251");
93        let y_mod = FixedMontyForm::new(&y, &params);
94
95        x_mod += &y_mod;
96
97        let expected =
98            U256::from_be_hex("1a2472fde50286541d97ca6a3592dd75beb9c9646e40c511b82496cfc3926956");
99
100        assert_eq!(expected, x_mod.retrieve());
101    }
102}
crypto_bigint/modular/fixed_monty_form/add.rs

crypto_bigint/modular/fixed_monty_form/
add.rs
