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ff: PrimeField::{is_even, is_odd}

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This commit is contained in:
Jack Grigg
2020-04-21 19:05:19 +12:00
parent 232f0a50b8
commit 1fdca393bb
10 changed files with 54 additions and 8 deletions
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5
zcash_primitives/src/jubjub/edwards.rs
View File

@@ -127,7 +127,7 @@ impl<E: JubjubEngine> Point<E, Unknown> {
tmp1.mul_assign(&tmp2);
tmp1.sqrt().map(|mut x| {
if x.into_repr().is_odd() != sign {
if x.is_odd() != sign {
x = x.neg();
}
@@ -172,9 +172,8 @@ impl<E: JubjubEngine, Subgroup> Point<E, Subgroup> {
assert_eq!(E::Fr::NUM_BITS, 255);
let x_repr = x.into_repr();
let mut y_repr = y.into_repr();
if x_repr.is_odd() {
if x.is_odd() {
y_repr.as_mut()[3] |= 0x8000000000000000u64;
}

5
zcash_primitives/src/jubjub/fs.rs
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@@ -481,6 +481,11 @@ impl PrimeField for Fs {
r.0
}
#[inline(always)]
fn is_odd(&self) -> bool {
self.into_repr().is_odd()
}
fn char() -> FsRepr {
MODULUS
}

4
zcash_primitives/src/jubjub/montgomery.rs
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@@ -1,4 +1,4 @@
use ff::{BitIterator, Field, PrimeField, PrimeFieldRepr, SqrtField};
use ff::{BitIterator, Field, PrimeField, SqrtField};
use std::ops::{AddAssign, MulAssign, Neg, SubAssign};
use subtle::CtOption;
@@ -60,7 +60,7 @@ impl<E: JubjubEngine> Point<E, Unknown> {
rhs.add_assign(&x2);
rhs.sqrt().map(|mut y| {
if y.into_repr().is_odd() != sign {
if y.is_odd() != sign {
y = y.neg();
}

2
zcash_primitives/src/jubjub/tests.rs
View File

@@ -237,7 +237,7 @@ fn test_get_for<E: JubjubEngine>(params: &E::Params) {
let p = edwards::Point::<E, _>::get_for_y(y, sign, params);
if bool::from(p.is_some()) {
let mut p = p.unwrap();
assert!(p.to_xy().0.into_repr().is_odd() == sign);
assert!(p.to_xy().0.is_odd() == sign);
p = p.negate();
assert!(edwards::Point::<E, _>::get_for_y(y, !sign, params).unwrap() == p);
}