Prepare support for non-Weierstrass EC equations.

* src/mpi.h (gcry_mpi_ec_models): New.
* src/ec-context.h (mpi_ec_ctx_s): Add MODEL.
* cipher/ecc-common.h (elliptic_curve_t): Ditto.
* cipher/ecc-curves.c (ecc_domain_parms_t): Ditto.
(domain_parms): Mark als as Weierstrass.
(_gcry_ecc_fill_in_curve): Check model.
(_gcry_ecc_get_curve): Set model to Weierstrass.
* cipher/ecc-misc.c (_gcry_ecc_model2str): New.
* cipher/ecc.c (generate_key, ecc_generate_ext): Print model in the
debug output.

* mpi/ec.c (_gcry_mpi_ec_dup_point): Switch depending on model.
Factor code out to ...
(dup_point_weierstrass): new.
(dup_point_montgomery, dup_point_twistededwards): New stub functions.
(_gcry_mpi_ec_add_points): Switch depending on model.  Factor code out
to ...
(add_points_weierstrass): new.
(add_points_montgomery, add_points_twistededwards): New stub
functions.

* tests/Makefile.am (TESTS): Reorder tests.

Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 85 insertions, 7 deletions

diff --git a/mpi/ec.c b/mpi/ec.c
index 8fb47a30..54fa0286 100644
--- a/mpi/ec.c
+++ b/mpi/ec.c
@@ -684,9 +684,9 @@ _gcry_mpi_ec_get_affine (gcry_mpi_t x, gcry_mpi_t y, mpi_point_t point,
 
 
 
-/*  RESULT = 2 * POINT  */
-void
-_gcry_mpi_ec_dup_point (mpi_point_t result, mpi_point_t point, mpi_ec_t ctx)
+/*  RESULT = 2 * POINT  (Weierstrass version). */
+static void
+dup_point_weierstrass (mpi_point_t result, mpi_point_t point, mpi_ec_t ctx)
 {
 #define x3 (result->x)
 #define y3 (result->y)
@@ -767,12 +767,48 @@ _gcry_mpi_ec_dup_point (mpi_point_t result, mpi_point_t point, mpi_ec_t ctx)
 }
 
 
+/*  RESULT = 2 * POINT  (Montgomery version). */
+static void
+dup_point_montgomery (mpi_point_t result, mpi_point_t point, mpi_ec_t ctx)
+{
+  log_fatal ("%s: %s not yet supported\n",
+             "_gcry_mpi_ec_dup_point", "Montgomery");
+}
+
 
-/* RESULT = P1 + P2 */
+/*  RESULT = 2 * POINT  (Twisted Edwards version). */
+static void
+dup_point_twistededwards (mpi_point_t result, mpi_point_t point, mpi_ec_t ctx)
+{
+  log_fatal ("%s: %s not yet supported\n",
+             "_gcry_mpi_ec_dup_point", "Twisted Edwards");
+}
+
+
+/*  RESULT = 2 * POINT  */
 void
-_gcry_mpi_ec_add_points (mpi_point_t result,
-                         mpi_point_t p1, mpi_point_t p2,
-                         mpi_ec_t ctx)
+_gcry_mpi_ec_dup_point (mpi_point_t result, mpi_point_t point, mpi_ec_t ctx)
+{
+  switch (ctx->model)
+    {
+    case MPI_EC_WEIERSTRASS:
+      dup_point_weierstrass (result, point, ctx);
+      break;
+    case MPI_EC_MONTGOMERY:
+      dup_point_montgomery (result, point, ctx);
+      break;
+    case MPI_EC_TWISTEDEDWARDS:
+      dup_point_twistededwards (result, point, ctx);
+      break;
+    }
+}
+
+
+/* RESULT = P1 + P2  (Weierstrass version).*/
+static void
+add_points_weierstrass (mpi_point_t result,
+                        mpi_point_t p1, mpi_point_t p2,
+                        mpi_ec_t ctx)
 {
 #define x1 (p1->x    )
 #define y1 (p1->y    )
@@ -910,6 +946,48 @@ _gcry_mpi_ec_add_points (mpi_point_t result,
 }
 
 
+/* RESULT = P1 + P2  (Montgomery version).*/
+static void
+add_points_montgomery (mpi_point_t result,
+                       mpi_point_t p1, mpi_point_t p2,
+                       mpi_ec_t ctx)
+{
+  log_fatal ("%s: %s not yet supported\n",
+             "_gcry_mpi_ec_add_points", "Montgomery");
+}
+
+
+/* RESULT = P1 + P2  (Twisted Edwards version).*/
+static void
+add_points_twistededwards (mpi_point_t result,
+                           mpi_point_t p1, mpi_point_t p2,
+                           mpi_ec_t ctx)
+{
+  log_fatal ("%s: %s not yet supported\n",
+             "_gcry_mpi_ec_add_points", "Twisted Edwards");
+}
+
+
+/* RESULT = P1 + P2 */
+void
+_gcry_mpi_ec_add_points (mpi_point_t result,
+                         mpi_point_t p1, mpi_point_t p2,
+                         mpi_ec_t ctx)
+{
+  switch (ctx->model)
+    {
+    case MPI_EC_WEIERSTRASS:
+      add_points_weierstrass (result, p1, p2, ctx);
+      break;
+    case MPI_EC_MONTGOMERY:
+      add_points_montgomery (result, p1, p2, ctx);
+      break;
+    case MPI_EC_TWISTEDEDWARDS:
+      add_points_twistededwards (result, p1, p2, ctx);
+      break;
+    }
+}
+
 
 /* Scalar point multiplication - the main function for ECC.  If takes
    an integer SCALAR and a POINT as well as the usual context CTX.