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Minimize use of lazy_static in ed448

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Increases usage of const values along with overall Field impl sanity 
with regards to the crypto_bigint backend.
This commit is contained in:
Luke Parker
2022-08-31 03:33:19 -04:00
parent a59bbe7635
commit 73566e756d
6 changed files with 100 additions and 112 deletions
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33
crypto/ed448/src/backend.rs
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@@ -6,10 +6,10 @@ macro_rules! field {
use rand_core::RngCore;
use subtle::{Choice, CtOption, ConstantTimeEq, ConditionallySelectable};
use subtle::{Choice, CtOption, ConstantTimeEq, ConstantTimeLess, ConditionallySelectable};
use generic_array::{typenum::U57, GenericArray};
use crypto_bigint::Encoding;
use crypto_bigint::{Integer, Encoding};
use ff::{Field, PrimeField, FieldBits, PrimeFieldBits};
@@ -38,7 +38,7 @@ macro_rules! field {
impl Neg for $FieldName {
type Output = $FieldName;
fn neg(self) -> $FieldName {
*$MODULUS - self
$MODULUS - self
}
}
@@ -49,21 +49,15 @@ macro_rules! field {
}
}
lazy_static! {
pub(crate) static ref ZERO: $FieldName = $FieldName(U512::ZERO);
pub(crate) static ref ONE: $FieldName = $FieldName(U512::ONE);
pub(crate) static ref TWO: $FieldName = $FieldName(U512::ONE.saturating_add(&U512::ONE));
}
impl $FieldName {
pub fn pow(&self, other: $FieldName) -> $FieldName {
let mut table = [*ONE; 16];
let mut table = [Self(U512::ONE); 16];
table[1] = *self;
for i in 2 .. 16 {
table[i] = table[i - 1] * self;
}
let mut res = *ONE;
let mut res = Self(U512::ONE);
let mut bits = 0;
for (i, bit) in other.to_le_bits().iter().rev().enumerate() {
bits <<= 1;
@@ -93,20 +87,21 @@ macro_rules! field {
}
fn zero() -> Self {
*ZERO
Self(U512::ZERO)
}
fn one() -> Self {
*ONE
Self(U512::ONE)
}
fn square(&self) -> Self {
*self * self
}
fn double(&self) -> Self {
*self + self
$FieldName((self.0 << 1).reduce(&$MODULUS.0).unwrap())
}
fn invert(&self) -> CtOption<Self> {
CtOption::new(self.pow(-*TWO), !self.is_zero())
const NEG_2: $FieldName = Self($MODULUS.0.saturating_sub(&U512::from_u8(2)));
CtOption::new(self.pow(NEG_2), !self.is_zero())
}
fn sqrt(&self) -> CtOption<Self> {
@@ -114,10 +109,10 @@ macro_rules! field {
}
fn is_zero(&self) -> Choice {
self.ct_eq(&ZERO)
self.0.ct_eq(&U512::ZERO)
}
fn cube(&self) -> Self {
*self * self * self
self.square() * self
}
fn pow_vartime<S: AsRef<[u64]>>(&self, _exp: S) -> Self {
unimplemented!()
@@ -130,7 +125,7 @@ macro_rules! field {
const CAPACITY: u32 = $NUM_BITS - 1;
fn from_repr(bytes: Self::Repr) -> CtOption<Self> {
let res = $FieldName(U512::from_le_slice(&[bytes.as_ref(), [0; 7].as_ref()].concat()));
CtOption::new(res, res.0.add_mod(&U512::ZERO, &$MODULUS.0).ct_eq(&res.0))
CtOption::new(res, res.0.ct_lt(&$MODULUS.0))
}
fn to_repr(&self) -> Self::Repr {
let mut repr = GenericArray::<u8, U57>::default();
@@ -141,7 +136,7 @@ macro_rules! field {
// True for both the Ed448 Scalar field and FieldElement field
const S: u32 = 1;
fn is_odd(&self) -> Choice {
(self.to_repr()[0] & 1).into()
self.0.is_odd()
}
fn multiplicative_generator() -> Self {
unimplemented!()