From: Niels Möller <nisse@lysator.liu.se>
Date: Sat, 13 Mar 2021 16:26:37 +0000 (+0100)
Subject: Use ecc_mod_mul_canonical for point comparison.
X-Git-Tag: nettle_3.7.2_release_20210321~7
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=971bed6ab4b27014eb23085e8176917e1a096fd5;p=thirdparty%2Fnettle.git

Use ecc_mod_mul_canonical for point comparison.

* eddsa-verify.c (equal_h): Use ecc_mod_mul_canonical.

(cherry picked from commit 5b7608fde3a6d2ab82bffb35db1e4e330927c906)
---

diff --git a/ChangeLog b/ChangeLog
index 5cc5c188..2a9217a6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2021-03-13  Niels Möller  <nisse@lysator.liu.se>
+
+	* eddsa-verify.c (equal_h): Use ecc_mod_mul_canonical.
+
 2021-03-11  Niels Möller  <nisse@lysator.liu.se>
 
 	* ecc-mod-arith.c (ecc_mod_mul_canonical, ecc_mod_sqr_canonical):
diff --git a/eddsa-verify.c b/eddsa-verify.c
index de68f240..10d075ee 100644
--- a/eddsa-verify.c
+++ b/eddsa-verify.c
@@ -53,13 +53,8 @@ equal_h (const struct ecc_modulo *p,
 #define t0 scratch
 #define t1 (scratch + p->size)
 
-  ecc_mod_mul (p, t0, x1, z2, t0);
-  if (mpn_cmp (t0, p->m, p->size) >= 0)
-    mpn_sub_n (t0, t0, p->m, p->size);
-
-  ecc_mod_mul (p, t1, x2, z1, t1);
-  if (mpn_cmp (t1, p->m, p->size) >= 0)
-    mpn_sub_n (t1, t1, p->m, p->size);
+  ecc_mod_mul_canonical (p, t0, x1, z2, t0);
+  ecc_mod_mul_canonical (p, t1, x2, z1, t1);
 
   return mpn_cmp (t0, t1, p->size) == 0;