Use ecc_mod_mul_canonical for point comparison.

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

(cherry picked from commit 5b7608fd)

ChangeLog

+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):

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;