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40 results

curve448-mul-g.c

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    Daiki Ueno authored and Niels Möller committed
    This patch adds the necessary primitives for "curve448", defined in
    RFC 7748.  Those primitives are namely: addition, doubling, scalar
    multiplication of the generator or an arbitrary point, inversion, and
    square root.
    389c787e
    History
    curve448-mul-g.c 1.94 KiB
    /* curve448-mul-g.c
    
       Copyright (C) 2017 Daiki Ueno
       Copyright (C) 2017 Red Hat, Inc.
    
       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 "curve448.h"
    
    #include "ecc.h"
    #include "ecc-internal.h"
    
    /* Intended to be compatible with NaCl's crypto_scalarmult_base. */
    void
    curve448_mul_g (uint8_t *r, const uint8_t *n)
    {
      const struct ecc_curve *ecc = &_nettle_curve448;
      uint8_t t[CURVE448_SIZE];
      mp_limb_t *scratch;
      mp_size_t itch;
    
    #define ng scratch
    #define x (scratch + 3*ecc->p.size)
    #define scratch_out (scratch + 4*ecc->p.size)
    
      memcpy (t, n, sizeof(t));
      t[0] &= ~3;
      t[CURVE448_SIZE-1] = (t[CURVE448_SIZE-1] & 0x7f) | 0x80;
    
      itch = 5*ecc->p.size + ecc->mul_g_itch;
      scratch = gmp_alloc_limbs (itch);
    
      mpn_set_base256_le (x, ecc->p.size, t, CURVE448_SIZE);
    
      ecc_mul_g_eh (ecc, ng, x, scratch_out);
      curve448_eh_to_x (x, ng, scratch_out);
    
      mpn_get_base256_le (r, CURVE448_SIZE, x, ecc->p.size);
      gmp_free_limbs (scratch, itch);
    #undef ng
    #undef x
    #undef scratch_out
    }