Handle O in _gcry_mpi_ec_mul_point for MPI_EC_MONTGOMERY.

2 files changed, 62 insertions, 6 deletions

diff --git a/mpi/ec.c b/mpi/ec.c
index ae2d6fa4..b312f532 100644
--- a/mpi/ec.c
+++ b/mpi/ec.c
@@ -1236,17 +1236,33 @@ _gcry_mpi_ec_mul_point (mpi_point_t result,
 
       z1 = mpi_new (0);
       mpi_clear (result->y);
-      mpi_set_ui (result->z, 1);
       if ((nbits & 1))
         {
-          ec_invm (z1, p1_.z, ctx);
-          ec_mulm (result->x, p1_.x, z1, ctx);
-          mpi_clear (result->y);
+	  if (p1_.z->nlimbs == 0)
+	    {
+	      mpi_set_ui (result->x, 1);
+	      mpi_set_ui (result->z, 0);
+	    }
+	  else
+	    {
+	      ec_invm (z1, p1_.z, ctx);
+	      ec_mulm (result->x, p1_.x, z1, ctx);
+	      mpi_set_ui (result->z, 1);
+	    }
         }
       else
         {
-          ec_invm (z1, p1.z, ctx);
-          ec_mulm (result->x, p1.x, z1, ctx);
+	  if (p1.z->nlimbs == 0)
+	    {
+	      mpi_set_ui (result->x, 1);
+	      mpi_set_ui (result->z, 0);
+	    }
+	  else
+	    {
+	      ec_invm (z1, p1.z, ctx);
+	      ec_mulm (result->x, p1.x, z1, ctx);
+	      mpi_set_ui (result->z, 1);
+	    }
         }
 
       mpi_free (z1);
@@ -1378,8 +1394,12 @@ _gcry_mpi_ec_curve_point (gcry_mpi_point_t point, mpi_ec_t ctx)
       }
       break;
     case MPI_EC_MONTGOMERY:
+#if 0
       log_fatal ("%s: %s not yet supported\n",
                  "_gcry_mpi_ec_curve_point", "Montgomery");
+#else
+      res = 1;
+#endif
       break;
     case MPI_EC_EDWARDS:
       {
diff --git a/tests/curves.c b/tests/curves.c
index 5dc9d6d8..ae699d49 100644
--- a/tests/curves.c
+++ b/tests/curves.c
@@ -103,6 +103,42 @@ die (const char *format, ...)
 }
 
 
+static gcry_mpi_t
+hex2mpi (const char *string)
+{
+  gpg_error_t err;
+  gcry_mpi_t val;
+
+  err = gcry_mpi_scan (&val, GCRYMPI_FMT_HEX, string, 0, NULL);
+  if (err)
+    die ("hex2mpi '%s' failed: %s\n", string, gpg_strerror (err));
+  return val;
+}
+
+
+/* Print an MPI S-expression.  */
+static void
+print_mpi (const char *name, gcry_mpi_t a)
+{
+  gcry_error_t err;
+  unsigned char *buf;
+  int writerr = 0;
+
+  err = gcry_mpi_aprint (GCRYMPI_FMT_HEX, &buf, NULL, a);
+  if (err)
+    die ("gcry_mpi_aprint failed: %s\n", gcry_strerror (err));
+
+  printf ("  (%s #%s#)\n", name, buf);
+  if (ferror (stdout))
+    writerr++;
+  if (!writerr && fflush (stdout) == EOF)
+    writerr++;
+  if (writerr)
+    die ("writing output failed\n");
+  gcry_free (buf);
+}
+
+
 static void
 list_curves (void)
 {