elliptic-curve: consolidate AffineCoordinates trait

elliptic-curve/src/arithmetic.rs

@@ -2,7 +2,7 @@
 
 use crate::{
     ops::{LinearCombination, MulByGenerator, Reduce, ShrAssign},
-    point::{AffineXCoordinate, AffineYIsOdd},
+    point::AffineCoordinates,
     scalar::FromUintUnchecked,
     scalar::IsHigh,
     Curve, FieldBytes, PrimeCurve, ScalarPrimitive,
@@ -15,8 +15,7 @@ use zeroize::DefaultIsZeroes;
 pub trait CurveArithmetic: Curve {
     /// Elliptic curve point in affine coordinates.
     type AffinePoint: 'static
-        + AffineXCoordinate<FieldRepr = FieldBytes<Self>>
-        + AffineYIsOdd
+        + AffineCoordinates<FieldRepr = FieldBytes<Self>>
         + Copy
         + ConditionallySelectable
         + ConstantTimeEq

elliptic-curve/src/dev.rs

@@ -9,7 +9,7 @@ use crate::{
     generic_array::typenum::U32,
     ops::{LinearCombination, MulByGenerator, Reduce, ShrAssign},
     pkcs8,
-    point::{AffineXCoordinate, AffineYIsOdd},
+    point::AffineCoordinates,
     rand_core::RngCore,
     scalar::{FromUintUnchecked, IsHigh},
     sec1::{CompressedPoint, FromEncodedPoint, ToEncodedPoint},
@@ -415,15 +415,13 @@ pub enum AffinePoint {
     Other(EncodedPoint),
 }
 
-impl AffineXCoordinate for AffinePoint {
+impl AffineCoordinates for AffinePoint {
     type FieldRepr = FieldBytes;
 
     fn x(&self) -> FieldBytes {
         unimplemented!();
     }
-}
 
-impl AffineYIsOdd for AffinePoint {
     fn y_is_odd(&self) -> Choice {
         unimplemented!();
     }

elliptic-curve/src/ecdh.rs

@@ -27,7 +27,7 @@
 //! [SIGMA]: https://webee.technion.ac.il/~hugo/sigma-pdf.pdf
 
 use crate::{
-    point::AffineXCoordinate, AffinePoint, Curve, CurveArithmetic, FieldBytes, NonZeroScalar,
+    point::AffineCoordinates, AffinePoint, Curve, CurveArithmetic, FieldBytes, NonZeroScalar,
     ProjectivePoint, PublicKey,
 };
 use core::borrow::Borrow;

elliptic-curve/src/point.rs

@@ -19,17 +19,15 @@ pub type AffinePoint<C> = <C as CurveArithmetic>::AffinePoint;
 #[cfg(feature = "arithmetic")]
 pub type ProjectivePoint<C> = <C as CurveArithmetic>::ProjectivePoint;
 
-/// Obtain the affine x-coordinate of an elliptic curve point.
-pub trait AffineXCoordinate {
+/// Access to the affine coordinates of an elliptic curve point.
+// TODO: use zkcrypto/group#30 coordinate API when available
+pub trait AffineCoordinates {
     /// Field element representation.
     type FieldRepr: AsRef<[u8]>;
 
     /// Get the affine x-coordinate as a serialized field element.
     fn x(&self) -> Self::FieldRepr;
-}
 
-/// Is the affine y-coordinate of this elliptic curve point odd?
-pub trait AffineYIsOdd {
     /// Is the affine y-coordinate odd?
     fn y_is_odd(&self) -> Choice;
 }