From 264be6ea2f50fdfaf3814bec7b44638fdb40bb69 Mon Sep 17 00:00:00 2001
From: Tony Arcieri <bascule@gmail.com>
Date: Sat, 25 Jul 2020 10:56:14 -0700
Subject: [PATCH] elliptic-curve: add `Arithmetic` trait

Several potentially useful traits (including the ECDSA ones) need access
to these types, so it's helpful to have a single trait that defines them
as associated types.

Some additional bounds would really be helpful, but we can add those as
they come up in practice.
---
 elliptic-curve/src/weierstrass/curve.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/elliptic-curve/src/weierstrass/curve.rs b/elliptic-curve/src/weierstrass/curve.rs
index c7fdf623a..1d0079282 100644
--- a/elliptic-curve/src/weierstrass/curve.rs
+++ b/elliptic-curve/src/weierstrass/curve.rs
@@ -16,5 +16,14 @@ pub trait Curve: Clone + Debug + Default + Eq + Ord + Send + Sync {
     type ScalarSize: ArrayLength<u8> + Add + Add<U1> + Eq + Ord + Unsigned;
 }
 
+/// Curve arithmetic support
+pub trait Arithmetic: Curve {
+    /// Scalar type for a given curve
+    type Scalar;
+
+    /// Affine point type for a given curve
+    type AffinePoint;
+}
+
 /// Alias for [`SecretKey`] type for a given Weierstrass curve
 pub type SecretKey<C> = crate::secret_key::SecretKey<<C as Curve>::ScalarSize>;