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elliptic-curve: add weierstrass::PublicKey::compress #243

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Merged
tarcieri merged 1 commit into from
Aug 3, 2020
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elliptic-curve: add weierstrass::PublicKey::compress #243

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10 changes: 10 additions & 0 deletions elliptic-curve/src/weierstrass/point.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -171,6 +171,16 @@ where
pub fn into_bytes(self) -> GenericArray<u8, UncompressedPointSize<C>> {
self.bytes
}

/// Get the x-coordinate of this curve point
pub(crate) fn x(&self) -> &ScalarBytes<C> {
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@tarcieri tarcieri Aug 3, 2020

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Something of a misuse of the Scalar part of ScalarBytes here... perhaps it should be renamed to ElementBytes to reflect the Curve::ElementSize rename (from Curve::ScalarSize)

GenericArray::from_slice(&self.bytes[1..(C::ElementSize::to_usize() + 1)])
}

/// Get the y-coordinate of this curve point
pub(crate) fn y(&self) -> &ScalarBytes<C> {
GenericArray::from_slice(&self.bytes[(C::ElementSize::to_usize() + 1)..])
}
}

impl<C: Curve> AsRef<[u8]> for UncompressedPoint<C>
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9 changes: 9 additions & 0 deletions elliptic-curve/src/weierstrass/public_key.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,15 @@ where
PublicKey::Uncompressed(UncompressedPoint::from_bytes(tagged_bytes).unwrap())
}

/// Compress this [`PublicKey`].
///
/// If the key is already compressed, this is a no-op.
pub fn compress(&mut self) {
if let PublicKey::Uncompressed(point) = self {
*self = CompressedPoint::from_affine_coords(point.x(), point.y()).into();
}
}

/// Obtain public key as a byte array reference
#[inline]
pub fn as_bytes(&self) -> &[u8] {
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