From 90656b0bbf04f73617906715f45bd759b68d384a Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Fri, 14 Oct 2016 12:03:50 -0600
Subject: [PATCH] Don't perform field inverse/squaring during affine conversion
 if point is already in affine.

---
 src/groups/mod.rs      | 5 +++++
 tests/serialization.rs | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/src/groups/mod.rs b/src/groups/mod.rs
index 8ff08ba..4afb8fd 100644
--- a/src/groups/mod.rs
+++ b/src/groups/mod.rs
@@ -112,6 +112,11 @@ impl<P: GroupParams> G<P> {
     pub fn to_affine(&self) -> Option<AffineG<P>> {
         if self.z.is_zero() {
             None
+        } else if self.z == P::Base::one() {
+            Some(AffineG {
+                x: self.x,
+                y: self.y
+            })
         } else {
             let zinv = self.z.inverse().unwrap();
             let zinv_squared = zinv.squared();
diff --git a/tests/serialization.rs b/tests/serialization.rs
index 9125df5..9377312 100644
--- a/tests/serialization.rs
+++ b/tests/serialization.rs
@@ -35,6 +35,7 @@ fn group_serialization_and_deserialization() {
         a = a * b;
 
         assert!(reserialize(a) == a);
+        assert!(reserialize(reserialize(a)) == a);
     }
 
     let mut a = G2::one();
@@ -42,6 +43,7 @@ fn group_serialization_and_deserialization() {
         a = a * b;
 
         assert!(reserialize(a) == a);
+        assert!(reserialize(reserialize(a)) == a);
     }
 }