From f2e53be88e886dd4c6188bf4fe847f57276a9216 Mon Sep 17 00:00:00 2001
From: Weikeng Chen <w.k@berkeley.edu>
Date: Sat, 3 Sep 2022 21:22:22 -0700
Subject: [PATCH] Montgomery cannot use TE affine as intermediate
 representations (#103)

* debug

* test

* use mont

* reduce the delta

Co-authored-by: onewayfunc <onewayfunc@gmail.com>
---
 src/groups/curves/twisted_edwards/mod.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/groups/curves/twisted_edwards/mod.rs b/src/groups/curves/twisted_edwards/mod.rs
index f7dbd93..789cb59 100644
--- a/src/groups/curves/twisted_edwards/mod.rs
+++ b/src/groups/curves/twisted_edwards/mod.rs
@@ -38,7 +38,7 @@ pub struct MontgomeryAffineVar<
 
 mod montgomery_affine_impl {
     use super::*;
-    use ark_ec::twisted_edwards::Affine as GroupAffine;
+    use ark_ec::twisted_edwards::MontgomeryAffine as GroupAffine;
     use ark_ff::Field;
     use core::ops::Add;
 
@@ -83,8 +83,8 @@ mod montgomery_affine_impl {
         pub fn from_edwards_to_coords(
             p: &TEAffine<P>,
         ) -> Result<(P::BaseField, P::BaseField), SynthesisError> {
-            let montgomery_point: GroupAffine<P> = if p.y == P::BaseField::one() {
-                GroupAffine::identity()
+            let montgomery_point: GroupAffine<P::MontCurveConfig> = if p.y == P::BaseField::one() {
+                return Err(SynthesisError::UnexpectedIdentity);
             } else if p.x == P::BaseField::zero() {
                 GroupAffine::new(P::BaseField::zero(), P::BaseField::zero())
             } else {