From e1193d2ae9f8266ea5424fda357a22a547e7053e Mon Sep 17 00:00:00 2001
From: Jack Grigg <thestr4d@gmail.com>
Date: Wed, 29 May 2019 17:30:24 +0100
Subject: [PATCH] impl Mul<Fr> for [Extended|Affine]NielsPoint

---
 src/lib.rs  | 31 +++++++++++++++++++++++++++++++
 src/util.rs | 22 ++++++++++++++--------
 2 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 7825724..efee90e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -252,6 +252,16 @@ impl AffineNielsPoint {
     }
 }
 
+impl<'a, 'b> Mul<&'b Fr> for &'a AffineNielsPoint {
+    type Output = ExtendedPoint;
+
+    fn mul(self, other: &'b Fr) -> ExtendedPoint {
+        self.multiply(&other.into_bytes())
+    }
+}
+
+impl_binops_multiplicative_mixed!(AffineNielsPoint, Fr, ExtendedPoint);
+
 impl ConditionallySelectable for AffineNielsPoint {
     fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
         AffineNielsPoint {
@@ -326,6 +336,16 @@ impl ExtendedNielsPoint {
     }
 }
 
+impl<'a, 'b> Mul<&'b Fr> for &'a ExtendedNielsPoint {
+    type Output = ExtendedPoint;
+
+    fn mul(self, other: &'b Fr) -> ExtendedPoint {
+        self.multiply(&other.into_bytes())
+    }
+}
+
+impl_binops_multiplicative_mixed!(ExtendedNielsPoint, Fr, ExtendedPoint);
+
 // `d = -(10240/10241)`
 const EDWARDS_D: Fq = Fq::from_raw([
     0x01065fd6d6343eb1,
@@ -1198,6 +1218,17 @@ fn test_mul_consistency() {
         ]),
     }).mul_by_cofactor();
     assert_eq!(p * c, (p * a) * b);
+
+    // Test Mul implemented on ExtendedNielsPoint
+    assert_eq!(p * c, (p.to_niels() * a) * b);
+    assert_eq!(p.to_niels() * c, (p * a) * b);
+    assert_eq!(p.to_niels() * c, (p.to_niels() * a) * b);
+
+    // Test Mul implemented on AffineNielsPoint
+    let p_affine_niels = AffinePoint::from(p).to_niels();
+    assert_eq!(p * c, (p_affine_niels * a) * b);
+    assert_eq!(p_affine_niels * c, (p * a) * b);
+    assert_eq!(p_affine_niels * c, (p_affine_niels * a) * b);
 }
 
 #[test]
diff --git a/src/util.rs b/src/util.rs
index f45ab01..05e0e48 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -105,34 +105,40 @@ macro_rules! impl_binops_additive {
     };
 }
 
-macro_rules! impl_binops_multiplicative {
-    ($lhs:ident, $rhs:ident) => {
+macro_rules! impl_binops_multiplicative_mixed {
+    ($lhs:ident, $rhs:ident, $output:ident) => {
         impl<'b> Mul<&'b $rhs> for $lhs {
-            type Output = $lhs;
+            type Output = $output;
 
             #[inline]
-            fn mul(self, rhs: &'b $rhs) -> $lhs {
+            fn mul(self, rhs: &'b $rhs) -> $output {
                 &self * rhs
             }
         }
 
         impl<'a> Mul<$rhs> for &'a $lhs {
-            type Output = $lhs;
+            type Output = $output;
 
             #[inline]
-            fn mul(self, rhs: $rhs) -> $lhs {
+            fn mul(self, rhs: $rhs) -> $output {
                 self * &rhs
             }
         }
 
         impl Mul<$rhs> for $lhs {
-            type Output = $lhs;
+            type Output = $output;
 
             #[inline]
-            fn mul(self, rhs: $rhs) -> $lhs {
+            fn mul(self, rhs: $rhs) -> $output {
                 &self * &rhs
             }
         }
+    };
+}
+
+macro_rules! impl_binops_multiplicative {
+    ($lhs:ident, $rhs:ident) => {
+        impl_binops_multiplicative_mixed!($lhs, $rhs, $lhs);
 
         impl MulAssign<$rhs> for $lhs {
             #[inline]