release/src/router/nettle/ecc-192.c

   1 /* ecc-192.c */
   2
   3 /* Compile time constant (but machine dependent) tables. */
   4
   5 /* nettle, low-level cryptographics library
   6  *
   7  * Copyright (C) 2013 Niels Möller
   8  *
   9  * The nettle library is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or (at your
  12  * option) any later version.
  13  *
  14  * The nettle library is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  16  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  17  * License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  21  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  22  * MA 02111-1301, USA.
  23  */
  24
  25 /* Development of Nettle's ECC support was funded by the .SE Internet Fund. */
  26
  27 #if HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <assert.h>
  32
  33 #include "ecc-internal.h"
  34
  35 #define USE_REDC 0
  36
  37 #include "ecc-192.h"
  38
  39 #if HAVE_NATIVE_ecc_192_modp
  40
  41 #define ecc_192_modp nettle_ecc_192_modp
  42 void
  43 ecc_192_modp (const struct ecc_curve *ecc, mp_limb_t *rp);
  44
  45 /* Use that p = 2^{192} - 2^64 - 1, to eliminate 128 bits at a time. */
  46
  47 #elif GMP_NUMB_BITS == 32
  48 /* p is 6 limbs, p = B^6 - B^2 - 1 */
  49 static void
  50 ecc_192_modp (const struct ecc_curve *ecc UNUSED, mp_limb_t *rp)
  51 {
  52   mp_limb_t cy;
  53
  54   /* Reduce from 12 to 9 limbs (top limb small)*/
  55   cy = mpn_add_n (rp + 2, rp + 2, rp + 8, 4);
  56   cy = sec_add_1 (rp + 6, rp + 6, 2, cy);
  57   cy += mpn_add_n (rp + 4, rp + 4, rp + 8, 4);
  58   assert (cy <= 2);
  59
  60   rp[8] = cy;
  61
  62   /* Reduce from 9 to 6 limbs */
  63   cy = mpn_add_n (rp, rp, rp + 6, 3);
  64   cy = sec_add_1 (rp + 3, rp + 3, 2, cy);
  65   cy += mpn_add_n (rp + 2, rp + 2, rp + 6, 3);
  66   cy = sec_add_1 (rp + 5, rp + 5, 1, cy);
  67
  68   assert (cy <= 1);
  69   cy = cnd_add_n (cy, rp, ecc_Bmodp, 6);
  70   assert (cy == 0);
  71 }
  72 #elif GMP_NUMB_BITS == 64
  73 /* p is 3 limbs, p = B^3 - B - 1 */
  74 static void
  75 ecc_192_modp (const struct ecc_curve *ecc UNUSED, mp_limb_t *rp)
  76 {
  77   mp_limb_t cy;
  78
  79   /* Reduce from 6 to 5 limbs (top limb small)*/
  80   cy = mpn_add_n (rp + 1, rp + 1, rp + 4, 2);
  81   cy = sec_add_1 (rp + 3, rp + 3, 1, cy);
  82   cy += mpn_add_n (rp + 2, rp + 2, rp + 4, 2);
  83   assert (cy <= 2);
  84
  85   rp[4] = cy;
  86
  87   /* Reduce from 5 to 4 limbs (high limb small) */
  88   cy = mpn_add_n (rp, rp, rp + 3, 2);
  89   cy = sec_add_1 (rp + 2, rp + 2, 1, cy);
  90   cy += mpn_add_n (rp + 1, rp + 1, rp + 3, 2);
  91
  92   assert (cy <= 1);
  93   cy = cnd_add_n (cy, rp, ecc_Bmodp, 3);
  94   assert (cy == 0);
  95 }
  96
  97 #else
  98 #define ecc_192_modp ecc_generic_modp
  99 #endif
 100
 101 const struct ecc_curve nettle_secp_192r1 =
 102 {
 103   192,
 104   ECC_LIMB_SIZE,
 105   ECC_BMODP_SIZE,
 106   ECC_BMODQ_SIZE,
 107   USE_REDC,
 108   ECC_REDC_SIZE,
 109   ECC_PIPPENGER_K,
 110   ECC_PIPPENGER_C,
 111   ecc_p,
 112   ecc_b,
 113   ecc_q,
 114   ecc_g,
 115   ecc_redc_g,
 116   ecc_192_modp,
 117   ecc_generic_redc,
 118   ecc_192_modp,
 119   ecc_generic_modq,
 120   ecc_Bmodp,
 121   ecc_Bmodp_shifted,
 122   ecc_pp1h,
 123   ecc_redc_ppm1,
 124   ecc_unit,
 125   ecc_Bmodq,
 126   ecc_Bmodq_shifted,
 127   ecc_qp1h,
 128   ecc_table
 129 };
 130