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Consolidate macros in dalek-ff-group

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This commit is contained in:
Luke Parker
2022-07-10 16:48:08 -04:00
parent 953a873338
commit cf28967754
2 changed files with 81 additions and 106 deletions
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56
crypto/dalek-ff-group/src/field.rs
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@@ -7,7 +7,7 @@ use crypto_bigint::{Encoding, U256, U512};
use ff::{Field, PrimeField, FieldBits, PrimeFieldBits};
use crate::{choice, from_wrapper, from_uint};
use crate::{choice, constant_time, math_op, math, from_wrapper, from_uint};
const FIELD_MODULUS: U256 = U256::from_be_hex(
"7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffed"
@@ -20,64 +20,30 @@ pub const SQRT_M1: FieldElement = FieldElement(
U256::from_be_hex("2b8324804fc1df0b2b4d00993dfbd7a72f431806ad2fe478c4ee1b274a0ea0b0")
);
macro_rules! math {
($Op: ident, $op_fn: ident, $Assign: ident, $assign_fn: ident, $function: expr) => {
impl $Op<FieldElement> for FieldElement {
type Output = Self;
fn $op_fn(self, other: FieldElement) -> Self::Output {
Self($function(&self.0, &other.0, &FIELD_MODULUS))
}
}
impl $Assign<FieldElement> for FieldElement {
fn $assign_fn(&mut self, other: FieldElement) {
self.0 = $function(&self.0, &other.0, &FIELD_MODULUS);
}
}
impl<'a> $Op<&'a FieldElement> for FieldElement {
type Output = Self;
fn $op_fn(self, other: &'a FieldElement) -> Self::Output {
Self($function(&self.0, &other.0, &FIELD_MODULUS))
}
}
impl<'a> $Assign<&'a FieldElement> for FieldElement {
fn $assign_fn(&mut self, other: &'a FieldElement) {
self.0 = $function(&self.0, &other.0, &FIELD_MODULUS);
}
}
}
}
math!(Add, add, AddAssign, add_assign, U256::add_mod);
math!(Sub, sub, SubAssign, sub_assign, U256::sub_mod);
constant_time!(FieldElement, U256);
math!(
Mul, mul,
MulAssign, mul_assign,
|a, b, _: &U256| {
FieldElement,
FieldElement,
|x, y| U256::add_mod(&x, &y, &FIELD_MODULUS),
|x, y| U256::sub_mod(&x, &y, &FIELD_MODULUS),
|x, y| {
#[allow(non_snake_case)]
let WIDE_MODULUS: U512 = U512::from((U256::ZERO, FIELD_MODULUS));
debug_assert_eq!(FIELD_MODULUS.to_le_bytes()[..], WIDE_MODULUS.to_le_bytes()[.. 32]);
let wide = U256::mul_wide(a, b);
let wide = U256::mul_wide(&x, &y);
U256::from_le_slice(
&U512::from((wide.1, wide.0)).reduce(&WIDE_MODULUS).unwrap().to_le_bytes()[.. 32]
)
}
);
from_uint!(FieldElement, U256);
impl Neg for FieldElement {
type Output = Self;
fn neg(self) -> Self::Output { Self(self.0.neg_mod(&FIELD_MODULUS)) }
}
impl ConstantTimeEq for FieldElement {
fn ct_eq(&self, other: &Self) -> Choice { self.0.ct_eq(&other.0) }
}
impl ConditionallySelectable for FieldElement {
fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
FieldElement(U256::conditional_select(&a.0, &b.0, choice))
}
}
impl Field for FieldElement {
fn random(mut rng: impl RngCore) -> Self {
let mut bytes = [0; 64];
@@ -119,8 +85,6 @@ impl Field for FieldElement {
fn pow_vartime<S: AsRef<[u64]>>(&self, _exp: S) -> Self { unimplemented!() }
}
from_uint!(FieldElement, U256);
impl PrimeField for FieldElement {
type Repr = [u8; 32];
const NUM_BITS: u32 = 255;
@@ -174,5 +138,5 @@ impl FieldElement {
fn test_mul() {
assert_eq!(FieldElement(FIELD_MODULUS) * FieldElement::one(), FieldElement::zero());
assert_eq!(FieldElement(FIELD_MODULUS) * FieldElement::one().double(), FieldElement::zero());
assert_eq!(FieldElement(SQRT_M1).square(), -FieldElement::one());
assert_eq!(SQRT_M1.square(), -FieldElement::one());
}