From 872252832f0456e4b7a2b21bc15c8753fe53941c Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Sun, 2 Apr 2017 12:50:25 -0600
Subject: [PATCH 1/2] The point at infinity is only representable in the
 jacobian at y = 1.

---
 src/groups/mod.rs | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/groups/mod.rs b/src/groups/mod.rs
index 1e08534..fb19ef7 100644
--- a/src/groups/mod.rs
+++ b/src/groups/mod.rs
@@ -383,10 +383,14 @@ impl<P: GroupParams> Neg for G<P> {
     type Output = G<P>;
 
     fn neg(self) -> G<P> {
-        G {
-            x: self.x,
-            y: -self.y,
-            z: self.z
+        if self.is_zero() {
+            self
+        } else {
+            G {
+                x: self.x,
+                y: -self.y,
+                z: self.z
+            }
         }
     }
 }

From b6f2ab337703286a78454fbfb62ad5d027b62cd4 Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Sun, 2 Apr 2017 13:48:53 -0600
Subject: [PATCH 2/2] Add test that y coordinate remains 1 in jacobian when
 G1/G2 are negated.

---
 src/groups/mod.rs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/groups/mod.rs b/src/groups/mod.rs
index fb19ef7..8983779 100644
--- a/src/groups/mod.rs
+++ b/src/groups/mod.rs
@@ -947,4 +947,12 @@ fn affine_fail() {
 fn affine_ok() {
     let res = AffineG1::new(Fq::one(), G1Params::coeff_b());
     assert!(res.is_err(), "Affine initialization should be ok because the point is on the curve");    
-}
\ No newline at end of file
+}
+
+fn test_y_at_point_at_infinity() {
+    assert!(G1::zero().y == Fq::one());
+    assert!((-G1::zero()).y == Fq::one());
+
+    assert!(G2::zero().y == Fq2::one());
+    assert!((-G2::zero()).y == Fq2::one());
+}