Renamed curve25519_base -> curve25519_mul_g.

1 files changed, 71 insertions, 0 deletions

diff --git a/curve25519-mul-g.c b/curve25519-mul-g.c
new file mode 100644
index 00000000..f98bee3d
--- /dev/null
+++ b/curve25519-mul-g.c
@@ -0,0 +1,71 @@
+/* curve25519-mul-g.c
+
+   Copyright (C) 2014 Niels Möller
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <string.h>
+
+#include "curve25519.h"
+
+#include "ecc.h"
+#include "ecc-internal.h"
+
+/* Intended to be compatible with NaCl's crypto_scalarmult_base. */
+void
+curve25519_mul_g (uint8_t *r, const uint8_t *n)
+{
+  uint8_t t[CURVE25519_SIZE];
+  mp_limb_t *scratch;
+  mp_size_t ecc_size;
+  mp_size_t itch;
+
+#define p scratch
+#define x (scratch + 3*ecc_size)
+#define scratch_out (scratch + 4*ecc_size)
+  
+  memcpy (t, n, sizeof(t));
+  t[0] &= ~7;
+  t[CURVE25519_SIZE-1] = (t[CURVE25519_SIZE-1] & 0x3f) | 0x40;
+
+  ecc_size = nettle_curve25519.size;
+  itch = 4*ecc_size + ECC_MUL_G_EH_ITCH(ecc_size);
+  scratch = gmp_alloc_limbs (itch);
+
+  mpn_set_base256_le (x, ecc_size, t, CURVE25519_SIZE);
+
+  ecc_mul_g_eh (&nettle_curve25519, p, x, scratch_out);
+  ecc_eh_to_a (&nettle_curve25519, 2, x, p, scratch_out);
+
+  mpn_get_base256_le (r, CURVE25519_SIZE, x, ecc_size);
+  gmp_free_limbs (scratch, itch);
+}