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Use GroupEncoding instead of Curve's from_slice/to_bytes

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Increases usage of standardization while expanding dalek_ff_group.

Closes https://github.com/serai-dex/serai/issues/26 by moving 
dfg::EdwardsPoint to only be for the prime subgroup.
This commit is contained in:
Luke Parker
2022-06-28 01:25:26 -04:00
parent ac17645fc8
commit 3de7a76051
14 changed files with 141 additions and 178 deletions
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42
crypto/frost/src/curve/kp256.rs
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@@ -1,14 +1,12 @@
use core::convert::TryInto;
use rand_core::{RngCore, CryptoRng};
use sha2::{digest::Update, Digest, Sha256};
use group::{ff::{Field, PrimeField}, Group, GroupEncoding};
use group::{ff::Field, GroupEncoding};
use elliptic_curve::{bigint::{Encoding, U384}, hash2curve::{Expander, ExpandMsg, ExpandMsgXmd}};
use crate::{curve::{CurveError, Curve}, algorithm::Hram};
use crate::{curve::{Curve, F_from_slice}, algorithm::Hram};
macro_rules! kp_curve {
(
@@ -65,7 +63,7 @@ macro_rules! kp_curve {
let mut modulus = vec![0; 16];
modulus.extend((Self::F::zero() - Self::F::one()).to_bytes());
let modulus = U384::from_be_slice(&modulus).wrapping_add(&U384::ONE);
Self::F_from_slice(
F_from_slice::<Self::F>(
&U384::from_be_slice(&{
let mut bytes = [0; 48];
ExpandMsgXmd::<Sha256>::expand_message(
@@ -85,38 +83,6 @@ macro_rules! kp_curve {
fn G_len() -> usize {
33
}
fn F_from_slice(slice: &[u8]) -> Result<Self::F, CurveError> {
let bytes: [u8; 32] = slice.try_into()
.map_err(|_| CurveError::InvalidLength(32, slice.len()))?;
let scalar = Self::F::from_repr(bytes.into());
if scalar.is_none().into() {
Err(CurveError::InvalidScalar)?;
}
Ok(scalar.unwrap())
}
fn G_from_slice(slice: &[u8]) -> Result<Self::G, CurveError> {
let bytes: [u8; 33] = slice.try_into()
.map_err(|_| CurveError::InvalidLength(33, slice.len()))?;
let point = Self::G::from_bytes(&bytes.into());
if point.is_none().into() || point.unwrap().is_identity().into() {
Err(CurveError::InvalidPoint)?;
}
Ok(point.unwrap())
}
fn F_to_bytes(f: &Self::F) -> Vec<u8> {
f.to_bytes().to_vec()
}
fn G_to_bytes(g: &Self::G) -> Vec<u8> {
g.to_bytes().to_vec()
}
}
#[derive(Clone)]
@@ -126,7 +92,7 @@ macro_rules! kp_curve {
fn hram(R: &$lib::ProjectivePoint, A: &$lib::ProjectivePoint, m: &[u8]) -> $lib::Scalar {
$Curve::hash_to_F(
&[$CONTEXT as &[u8], b"chal"].concat(),
&[&$Curve::G_to_bytes(R), &$Curve::G_to_bytes(A), m].concat()
&[R.to_bytes().as_ref(), A.to_bytes().as_ref(), m].concat()
)
}
}