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Add FromUniformBytes<64> to {k,p}256::Scalar #1379

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Merged
merged 1 commit into from
Sep 3, 2025
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Add FromUniformBytes<64> to {k,p}256::Scalar #1379

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8 changes: 7 additions & 1 deletion k256/src/arithmetic/scalar.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@ use core::{
use elliptic_curve::{
Curve, Error, ScalarPrimitive,
bigint::{Limb, U256, U512, Word, prelude::*},
ff::{self, Field, PrimeField},
ff::{self, Field, FromUniformBytes, PrimeField},
ops::{Invert, Reduce, ReduceNonZero},
rand_core::{CryptoRng, TryCryptoRng, TryRngCore},
scalar::{FromUintUnchecked, IsHigh},
Expand Down Expand Up @@ -380,6 +380,12 @@ impl From<u128> for Scalar {
}
}

impl FromUniformBytes<64> for Scalar {
fn from_uniform_bytes(bytes: &[u8; 64]) -> Self {
WideScalar::from_bytes(bytes).reduce()
}
}

impl From<NonZeroScalar> for Scalar {
fn from(scalar: NonZeroScalar) -> Self {
*scalar.as_ref()
Expand Down
11 changes: 10 additions & 1 deletion p256/src/arithmetic/scalar.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ use core::{
use elliptic_curve::{
Curve,
bigint::{Limb, NonZero, U256, prelude::*},
group::ff::{self, Field, PrimeField},
group::ff::{self, Field, FromUniformBytes, PrimeField},
ops::{Invert, Reduce, ReduceNonZero},
rand_core::TryRngCore,
scalar::{FromUintUnchecked, IsHigh},
Expand Down Expand Up @@ -489,6 +489,15 @@ impl From<&Scalar> for U256 {
}
}

impl FromUniformBytes<64> for Scalar {
fn from_uniform_bytes(bytes: &[u8; 64]) -> Self {
Self(barrett_reduce(
U256::from_be_slice(&bytes[32..]),
U256::from_be_slice(&bytes[..32]),
))
}
}

#[cfg(feature = "bits")]
impl From<&Scalar> for ScalarBits {
fn from(scalar: &Scalar) -> ScalarBits {
Expand Down