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Move FROST to Read
Fixes https://github.com/serai-dex/serai/issues/33 and https://github.com/serai-dex/serai/issues/35. Also fixes a few potential panics/DoS AFAICT.
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@@ -1,4 +1,5 @@
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use core::fmt::Debug;
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use std::io::Read;
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use thiserror::Error;
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@@ -77,41 +78,37 @@ pub trait Curve: Clone + Copy + PartialEq + Eq + Debug {
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// hash_msg and hash_binding_factor
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#[allow(non_snake_case)]
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fn hash_to_F(dst: &[u8], msg: &[u8]) -> Self::F;
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}
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#[allow(non_snake_case)]
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pub(crate) fn F_len<C: Curve>() -> usize {
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<C::F as PrimeField>::Repr::default().as_ref().len()
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}
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#[allow(non_snake_case)]
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pub(crate) fn G_len<C: Curve>() -> usize {
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<C::G as GroupEncoding>::Repr::default().as_ref().len()
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}
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/// Field element from slice
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#[allow(non_snake_case)]
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pub(crate) fn F_from_slice<F: PrimeField>(slice: &[u8]) -> Result<F, CurveError> {
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let mut encoding = F::Repr::default();
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encoding.as_mut().copy_from_slice(slice);
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let point = Option::<F>::from(F::from_repr(encoding)).ok_or(CurveError::InvalidScalar)?;
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if point.to_repr().as_ref() != slice {
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Err(CurveError::InvalidScalar)?;
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#[allow(non_snake_case)]
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fn F_len() -> usize {
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<Self::F as PrimeField>::Repr::default().as_ref().len()
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}
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Ok(point)
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}
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/// Group element from slice
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#[allow(non_snake_case)]
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pub(crate) fn G_from_slice<G: PrimeGroup>(slice: &[u8]) -> Result<G, CurveError> {
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let mut encoding = G::Repr::default();
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encoding.as_mut().copy_from_slice(slice);
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let point = Option::<G>::from(G::from_bytes(&encoding)).ok_or(CurveError::InvalidPoint)?;
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// Ban the identity, per the FROST spec, and non-canonical points
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if (point.is_identity().into()) || (point.to_bytes().as_ref() != slice) {
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Err(CurveError::InvalidPoint)?;
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#[allow(non_snake_case)]
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fn G_len() -> usize {
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<Self::G as GroupEncoding>::Repr::default().as_ref().len()
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}
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#[allow(non_snake_case)]
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fn read_F<R: Read>(r: &mut R) -> Result<Self::F, CurveError> {
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let mut encoding = <Self::F as PrimeField>::Repr::default();
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r.read_exact(encoding.as_mut()).map_err(|_| CurveError::InvalidScalar)?;
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// ff mandates this is canonical
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Option::<Self::F>::from(Self::F::from_repr(encoding)).ok_or(CurveError::InvalidScalar)
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}
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#[allow(non_snake_case)]
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fn read_G<R: Read>(r: &mut R) -> Result<Self::G, CurveError> {
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let mut encoding = <Self::G as GroupEncoding>::Repr::default();
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r.read_exact(encoding.as_mut()).map_err(|_| CurveError::InvalidPoint)?;
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let point = Option::<Self::G>::from(
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Self::G::from_bytes(&encoding)
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).ok_or(CurveError::InvalidPoint)?;
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// Ban the identity, per the FROST spec, and non-canonical points
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if (point.is_identity().into()) || (point.to_bytes().as_ref() != encoding.as_ref()) {
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Err(CurveError::InvalidPoint)?;
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}
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Ok(point)
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}
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Ok(point)
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}
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