From: Loup Vaillant <loup@loup-vaillant.fr>
Date: Mon, 24 Feb 2020 00:06:12 +0000 (+0100)
Subject: Elligator script: hoisted constant out
X-Git-Url: https://git.codecow.com/?a=commitdiff_plain;h=8297e3f784002d8b593626f7f7a9886e9772ad32;p=Monocypher.git

Elligator script: hoisted constant out
---

diff --git a/tests/gen/elligator.py b/tests/gen/elligator.py
index 8c78047..d4deb77 100755
--- a/tests/gen/elligator.py
+++ b/tests/gen/elligator.py
@@ -278,6 +278,8 @@ def explicit_curve_to_hash(point):
     # wipe temporaries: ua, c, sq1, sq2, sqv, t1, t2, t3, t4, t5
     return sq1
 
+half_A = A // 2
+
 # Explicit formula for hash_to_curve
 # We don't need the v coordinate for X25519, so it is omited
 def explicit_hash_to_curve(r):
@@ -291,9 +293,8 @@ def explicit_hash_to_curve(r):
     e = e + fe(1)
     e = e * w
     e = chi(e)
-    t = A // 2  # constant
     u = fe(1) - e
-    u = u * t
+    u = u * half_A
     w = e * w
     u = w - u
     return u