crypto/openssl-0.9/crypto/bn/bn_nist.c

   1 /* crypto/bn/bn_nist.c */
   2 /*
   3  * Written by Nils Larsch for the OpenSSL project
   4  */
   5 /* ====================================================================
   6  * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  *
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in
  17  *    the documentation and/or other materials provided with the
  18  *    distribution.
  19  *
  20  * 3. All advertising materials mentioning features or use of this
  21  *    software must display the following acknowledgment:
  22  *    "This product includes software developed by the OpenSSL Project
  23  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  24  *
  25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  26  *    endorse or promote products derived from this software without
  27  *    prior written permission. For written permission, please contact
  28  *    openssl-core@openssl.org.
  29  *
  30  * 5. Products derived from this software may not be called "OpenSSL"
  31  *    nor may "OpenSSL" appear in their names without prior written
  32  *    permission of the OpenSSL Project.
  33  *
  34  * 6. Redistributions of any form whatsoever must retain the following
  35  *    acknowledgment:
  36  *    "This product includes software developed by the OpenSSL Project
  37  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  38  *
  39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  50  * OF THE POSSIBILITY OF SUCH DAMAGE.
  51  * ====================================================================
  52  *
  53  * This product includes cryptographic software written by Eric Young
  54  * (eay@cryptsoft.com).  This product includes software written by Tim
  55  * Hudson (tjh@cryptsoft.com).
  56  *
  57  */
  58
  59 #include "bn_lcl.h"
  60 #include "cryptlib.h"
  61
  62 #define BN_NIST_192_TOP (192+BN_BITS2-1)/BN_BITS2
  63 #define BN_NIST_224_TOP (224+BN_BITS2-1)/BN_BITS2
  64 #define BN_NIST_256_TOP (256+BN_BITS2-1)/BN_BITS2
  65 #define BN_NIST_384_TOP (384+BN_BITS2-1)/BN_BITS2
  66 #define BN_NIST_521_TOP (521+BN_BITS2-1)/BN_BITS2
  67
  68 #if BN_BITS2 == 64
  69 static const BN_ULONG _nist_p_192[] =
  70         {0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFEULL,
  71         0xFFFFFFFFFFFFFFFFULL};
  72 static const BN_ULONG _nist_p_224[] =
  73         {0x0000000000000001ULL,0xFFFFFFFF00000000ULL,
  74         0xFFFFFFFFFFFFFFFFULL,0x00000000FFFFFFFFULL};
  75 static const BN_ULONG _nist_p_256[] =
  76         {0xFFFFFFFFFFFFFFFFULL,0x00000000FFFFFFFFULL,
  77         0x0000000000000000ULL,0xFFFFFFFF00000001ULL};
  78 static const BN_ULONG _nist_p_384[] =
  79         {0x00000000FFFFFFFFULL,0xFFFFFFFF00000000ULL,
  80         0xFFFFFFFFFFFFFFFEULL,0xFFFFFFFFFFFFFFFFULL,
  81         0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL};
  82 static const BN_ULONG _nist_p_521[] =
  83         {0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
  84         0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
  85         0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
  86         0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
  87         0x00000000000001FFULL};
  88 #elif BN_BITS2 == 32
  89 static const BN_ULONG _nist_p_192[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFE,
  90         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF};
  91 static const BN_ULONG _nist_p_224[] = {0x00000001,0x00000000,0x00000000,
  92         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF};
  93 static const BN_ULONG _nist_p_256[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
  94         0x00000000,0x00000000,0x00000000,0x00000001,0xFFFFFFFF};
  95 static const BN_ULONG _nist_p_384[] = {0xFFFFFFFF,0x00000000,0x00000000,
  96         0xFFFFFFFF,0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
  97         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF};
  98 static const BN_ULONG _nist_p_521[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
  99         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
 100         0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
 101         0xFFFFFFFF,0x000001FF};
 102 #endif
 103
 104 const BIGNUM *BN_get0_nist_prime_192(void)
 105         {
 106         static BIGNUM const_nist_192 = { (BN_ULONG *)_nist_p_192,
 107                 BN_NIST_192_TOP, BN_NIST_192_TOP, 0, BN_FLG_STATIC_DATA };
 108         return &const_nist_192;
 109         }
 110
 111 const BIGNUM *BN_get0_nist_prime_224(void)
 112         {
 113         static BIGNUM const_nist_224 = { (BN_ULONG *)_nist_p_224,
 114                 BN_NIST_224_TOP, BN_NIST_224_TOP, 0, BN_FLG_STATIC_DATA };
 115         return &const_nist_224;
 116         }
 117
 118 const BIGNUM *BN_get0_nist_prime_256(void)
 119         {
 120         static BIGNUM const_nist_256 = { (BN_ULONG *)_nist_p_256,
 121                 BN_NIST_256_TOP, BN_NIST_256_TOP, 0, BN_FLG_STATIC_DATA };
 122         return &const_nist_256;
 123         }
 124
 125 const BIGNUM *BN_get0_nist_prime_384(void)
 126         {
 127         static BIGNUM const_nist_384 = { (BN_ULONG *)_nist_p_384,
 128                 BN_NIST_384_TOP, BN_NIST_384_TOP, 0, BN_FLG_STATIC_DATA };
 129         return &const_nist_384;
 130         }
 131
 132 const BIGNUM *BN_get0_nist_prime_521(void)
 133         {
 134         static BIGNUM const_nist_521 = { (BN_ULONG *)_nist_p_521,
 135                 BN_NIST_521_TOP, BN_NIST_521_TOP, 0, BN_FLG_STATIC_DATA };
 136         return &const_nist_521;
 137         }
 138
 139 #define BN_NIST_ADD_ONE(a)      while (!(*(a)=(*(a)+1)&BN_MASK2)) ++(a);
 140
 141 static void nist_cp_bn_0(BN_ULONG *buf, BN_ULONG *a, int top, int max)
 142         {
 143         int i;
 144         BN_ULONG *_tmp1 = (buf), *_tmp2 = (a);
 145         for (i = (top); i != 0; i--)
 146                 *_tmp1++ = *_tmp2++;
 147         for (i = (max) - (top); i != 0; i--)
 148                 *_tmp1++ = (BN_ULONG) 0;
 149         }
 150
 151 static void nist_cp_bn(BN_ULONG *buf, BN_ULONG *a, int top)
 152         {
 153         int i;
 154         BN_ULONG *_tmp1 = (buf), *_tmp2 = (a);
 155         for (i = (top); i != 0; i--)
 156                 *_tmp1++ = *_tmp2++;
 157         }
 158
 159 #if BN_BITS2 == 64
 160 #define bn_cp_64(to, n, from, m)        (to)[n] = (m>=0)?((from)[m]):0;
 161 #define bn_64_set_0(to, n)              (to)[n] = (BN_ULONG)0;
 162 /* TBD */
 163 #define bn_cp_32(to, n, from, m)        (to)[n] = (m>=0)?((from)[m]):0;
 164 #define bn_32_set_0(to, n)              (to)[n] = (BN_ULONG)0;
 165 #else
 166 #define bn_cp_64(to, n, from, m) \
 167         { \
 168         bn_cp_32(to, (n)*2, from, (m)*2); \
 169         bn_cp_32(to, (n)*2+1, from, (m)*2+1); \
 170         }
 171 #define bn_64_set_0(to, n) \
 172         { \
 173         bn_32_set_0(to, (n)*2); \
 174         bn_32_set_0(to, (n)*2+1); \
 175         }
 176 #if BN_BITS2 == 32
 177 #define bn_cp_32(to, n, from, m)        (to)[n] = (m>=0)?((from)[m]):0;
 178 #define bn_32_set_0(to, n)              (to)[n] = (BN_ULONG)0;
 179 #endif
 180 #endif /* BN_BITS2 != 64 */
 181
 182
 183 #define nist_set_192(to, from, a1, a2, a3) \
 184         { \
 185         if (a3 != 0) bn_cp_64(to, 0, from, (a3) - 3) else bn_64_set_0(to, 0)\
 186         bn_cp_64(to, 1, from, (a2) - 3) \
 187         if (a1 != 0) bn_cp_64(to, 2, from, (a1) - 3) else bn_64_set_0(to, 2)\
 188         }
 189
 190 int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 191         BN_CTX *ctx)
 192         {
 193         int      top = a->top, i;
 194         int      carry;
 195         register BN_ULONG *r_d, *a_d = a->d;
 196         BN_ULONG t_d[BN_NIST_192_TOP],
 197                  buf[BN_NIST_192_TOP],
 198                  c_d[BN_NIST_192_TOP],
 199                 *res;
 200         size_t   mask;
 201
 202         i = BN_ucmp(field, a);
 203         if (i == 0)
 204                 {
 205                 BN_zero(r);
 206                 return 1;
 207                 }
 208         else if (i > 0)
 209                 return (r == a) ? 1 : (BN_copy(r ,a) != NULL);
 210
 211         if (top == BN_NIST_192_TOP)
 212                 return BN_usub(r, a, field);
 213
 214         if (r != a)
 215                 {
 216                 if (!bn_wexpand(r, BN_NIST_192_TOP))
 217                         return 0;
 218                 r_d = r->d;
 219                 nist_cp_bn(r_d, a_d, BN_NIST_192_TOP);
 220                 }
 221         else
 222                 r_d = a_d;
 223
 224         nist_cp_bn_0(buf, a_d + BN_NIST_192_TOP, top - BN_NIST_192_TOP, BN_NIST_192_TOP);
 225
 226         nist_set_192(t_d, buf, 0, 3, 3);
 227         carry = bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
 228         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_192,BN_NIST_192_TOP);
 229         mask = ~mask | (0-(size_t)carry);
 230         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 231
 232         nist_set_192(t_d, buf, 4, 4, 0);
 233         carry = bn_add_words(r_d, res, t_d, BN_NIST_192_TOP);
 234         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_192,BN_NIST_192_TOP);
 235         mask = ~mask | (0-(size_t)carry);
 236         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 237
 238         nist_set_192(t_d, buf, 5, 5, 5)
 239         carry = bn_add_words(r_d, res, t_d, BN_NIST_192_TOP);
 240         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_192,BN_NIST_192_TOP);
 241         mask = ~mask | (0-(size_t)carry);
 242         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 243
 244         nist_cp_bn(r_d, res, BN_NIST_192_TOP);
 245         r->top = BN_NIST_192_TOP;
 246         bn_correct_top(r);
 247
 248         return 1;
 249         }
 250
 251 #define nist_set_224(to, from, a1, a2, a3, a4, a5, a6, a7) \
 252         { \
 253         if (a7 != 0) bn_cp_32(to, 0, from, (a7) - 7) else bn_32_set_0(to, 0)\
 254         if (a6 != 0) bn_cp_32(to, 1, from, (a6) - 7) else bn_32_set_0(to, 1)\
 255         if (a5 != 0) bn_cp_32(to, 2, from, (a5) - 7) else bn_32_set_0(to, 2)\
 256         if (a4 != 0) bn_cp_32(to, 3, from, (a4) - 7) else bn_32_set_0(to, 3)\
 257         if (a3 != 0) bn_cp_32(to, 4, from, (a3) - 7) else bn_32_set_0(to, 4)\
 258         if (a2 != 0) bn_cp_32(to, 5, from, (a2) - 7) else bn_32_set_0(to, 5)\
 259         if (a1 != 0) bn_cp_32(to, 6, from, (a1) - 7) else bn_32_set_0(to, 6)\
 260         }
 261
 262 int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 263         BN_CTX *ctx)
 264         {
 265 #if BN_BITS2 == 32
 266         int     top = a->top, i;
 267         int     carry;
 268         BN_ULONG *r_d, *a_d = a->d;
 269         BN_ULONG t_d[BN_NIST_224_TOP],
 270                  buf[BN_NIST_224_TOP],
 271                  c_d[BN_NIST_224_TOP],
 272                 *res;
 273         size_t   mask;
 274
 275         i = BN_ucmp(field, a);
 276         if (i == 0)
 277                 {
 278                 BN_zero(r);
 279                 return 1;
 280                 }
 281         else if (i > 0)
 282                 return (r == a)? 1 : (BN_copy(r ,a) != NULL);
 283
 284         if (top == BN_NIST_224_TOP)
 285                 return BN_usub(r, a, field);
 286
 287         if (r != a)
 288                 {
 289                 if (!bn_wexpand(r, BN_NIST_224_TOP))
 290                         return 0;
 291                 r_d = r->d;
 292                 nist_cp_bn(r_d, a_d, BN_NIST_224_TOP);
 293                 }
 294         else
 295                 r_d = a_d;
 296
 297         nist_cp_bn_0(buf, a_d + BN_NIST_224_TOP, top - BN_NIST_224_TOP, BN_NIST_224_TOP);
 298
 299         nist_set_224(t_d, buf, 10, 9, 8, 7, 0, 0, 0);
 300         carry = bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
 301         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_224,BN_NIST_224_TOP);
 302         mask = ~mask | (0-(size_t)carry);
 303         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 304
 305         nist_set_224(t_d, buf, 0, 13, 12, 11, 0, 0, 0);
 306         carry = bn_add_words(r_d, res, t_d, BN_NIST_224_TOP);
 307         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_224,BN_NIST_224_TOP);
 308         mask = ~mask | (0-(size_t)carry);
 309         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 310
 311         nist_set_224(t_d, buf, 13, 12, 11, 10, 9, 8, 7);
 312 #if BRANCH_FREE
 313         carry = bn_sub_words(r_d, res, t_d, BN_NIST_224_TOP);
 314         bn_add_words(c_d,r_d,_nist_p_224,BN_NIST_224_TOP);
 315         mask = 0-(size_t)carry;
 316         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 317 #else
 318         if (bn_sub_words(r_d, res, t_d, BN_NIST_224_TOP))
 319                 bn_add_words(r_d,r_d,_nist_p_224,BN_NIST_224_TOP);
 320 #endif
 321         nist_set_224(t_d, buf, 0, 0, 0, 0, 13, 12, 11);
 322 #if BRANCH_FREE
 323         carry = bn_sub_words(r_d, res, t_d, BN_NIST_224_TOP);
 324         bn_add_words(c_d,r_d,_nist_p_224,BN_NIST_224_TOP);
 325         mask = 0-(size_t)carry;
 326         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 327
 328         nist_cp_bn(r_d, res, BN_NIST_224_TOP);
 329 #else
 330         if (bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP))
 331                 bn_add_words(r_d,r_d,_nist_p_224,BN_NIST_224_TOP);
 332 #endif
 333         r->top = BN_NIST_224_TOP;
 334         bn_correct_top(r);
 335
 336         return 1;
 337 #else   /* BN_BITS!=32 */
 338         return 0;
 339 #endif
 340         }
 341
 342 #define nist_set_256(to, from, a1, a2, a3, a4, a5, a6, a7, a8) \
 343         { \
 344         if (a8 != 0) bn_cp_32(to, 0, from, (a8) - 8) else bn_32_set_0(to, 0)\
 345         if (a7 != 0) bn_cp_32(to, 1, from, (a7) - 8) else bn_32_set_0(to, 1)\
 346         if (a6 != 0) bn_cp_32(to, 2, from, (a6) - 8) else bn_32_set_0(to, 2)\
 347         if (a5 != 0) bn_cp_32(to, 3, from, (a5) - 8) else bn_32_set_0(to, 3)\
 348         if (a4 != 0) bn_cp_32(to, 4, from, (a4) - 8) else bn_32_set_0(to, 4)\
 349         if (a3 != 0) bn_cp_32(to, 5, from, (a3) - 8) else bn_32_set_0(to, 5)\
 350         if (a2 != 0) bn_cp_32(to, 6, from, (a2) - 8) else bn_32_set_0(to, 6)\
 351         if (a1 != 0) bn_cp_32(to, 7, from, (a1) - 8) else bn_32_set_0(to, 7)\
 352         }
 353
 354 int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 355         BN_CTX *ctx)
 356         {
 357 #if BN_BITS2 == 32
 358         int     i, top = a->top;
 359         int     carry = 0;
 360         register BN_ULONG *a_d = a->d, *r_d;
 361         BN_ULONG t_d[BN_NIST_256_TOP],
 362                  buf[BN_NIST_256_TOP],
 363                  c_d[BN_NIST_256_TOP],
 364                 *res;
 365         size_t   mask;
 366
 367         i = BN_ucmp(field, a);
 368         if (i == 0)
 369                 {
 370                 BN_zero(r);
 371                 return 1;
 372                 }
 373         else if (i > 0)
 374                 return (r == a)? 1 : (BN_copy(r ,a) != NULL);
 375
 376         if (top == BN_NIST_256_TOP)
 377                 return BN_usub(r, a, field);
 378
 379         if (r != a)
 380                 {
 381                 if (!bn_wexpand(r, BN_NIST_256_TOP))
 382                         return 0;
 383                 r_d = r->d;
 384                 nist_cp_bn(r_d, a_d, BN_NIST_256_TOP);
 385                 }
 386         else
 387                 r_d = a_d;
 388
 389         nist_cp_bn_0(buf, a_d + BN_NIST_256_TOP, top - BN_NIST_256_TOP, BN_NIST_256_TOP);
 390
 391         /*S1*/
 392         nist_set_256(t_d, buf, 15, 14, 13, 12, 11, 0, 0, 0);
 393         /*S2*/
 394         nist_set_256(c_d,buf, 0, 15, 14, 13, 12, 0, 0, 0);
 395         carry = bn_add_words(t_d, t_d, c_d, BN_NIST_256_TOP);
 396         mask = 0-(size_t)bn_sub_words(c_d,t_d,_nist_p_256,BN_NIST_256_TOP);
 397         mask = ~mask | (0-(size_t)carry);
 398         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)t_d&~mask));
 399
 400         carry = bn_add_words(t_d, res, res, BN_NIST_256_TOP);
 401         mask = 0-(size_t)bn_sub_words(c_d,t_d,_nist_p_256,BN_NIST_256_TOP);
 402         mask = ~mask | (0-(size_t)carry);
 403         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)t_d&~mask));
 404
 405         carry = bn_add_words(r_d, r_d, res, BN_NIST_256_TOP);
 406         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 407         mask = ~mask | (0-(size_t)carry);
 408         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 409
 410         /*S3*/
 411         nist_set_256(t_d, buf, 15, 14, 0, 0, 0, 10, 9, 8);
 412         carry = bn_add_words(r_d, res, t_d, BN_NIST_256_TOP);
 413         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 414         mask = ~mask | (0-(size_t)carry);
 415         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 416
 417         /*S4*/
 418         nist_set_256(t_d, buf, 8, 13, 15, 14, 13, 11, 10, 9);
 419         carry = bn_add_words(r_d, res, t_d, BN_NIST_256_TOP);
 420         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 421         mask = ~mask | (0-(size_t)carry);
 422         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 423
 424         /*D1*/
 425         nist_set_256(t_d, buf, 10, 8, 0, 0, 0, 13, 12, 11);
 426 #if BRANCH_FREE
 427         carry = bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP);
 428         bn_add_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 429         mask = 0-(size_t)carry;
 430         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 431 #else
 432         if (bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP))
 433                 bn_add_words(r_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 434 #endif
 435         /*D2*/
 436         nist_set_256(t_d, buf, 11, 9, 0, 0, 15, 14, 13, 12);
 437 #if BRANCH_FREE
 438         carry = bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP);
 439         bn_add_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 440         mask = 0-(size_t)carry;
 441         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 442 #else
 443         if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 444                 bn_add_words(r_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 445 #endif
 446         /*D3*/
 447         nist_set_256(t_d, buf, 12, 0, 10, 9, 8, 15, 14, 13);
 448 #if BRANCH_FREE
 449         carry = bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP);
 450         bn_add_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 451         mask = 0-(size_t)carry;
 452         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 453 #else
 454         if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 455                 bn_add_words(r_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 456 #endif
 457         /*D4*/
 458         nist_set_256(t_d, buf, 13, 0, 11, 10, 9, 0, 15, 14);
 459 #if BRANCH_FREE
 460         carry = bn_sub_words(r_d, res, t_d, BN_NIST_256_TOP);
 461         bn_add_words(c_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 462         mask = 0-(size_t)carry;
 463         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 464
 465         nist_cp_bn(r_d, res, BN_NIST_384_TOP);
 466 #else
 467         if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 468                 bn_add_words(r_d,r_d,_nist_p_256,BN_NIST_256_TOP);
 469 #endif
 470         r->top = BN_NIST_256_TOP;
 471         bn_correct_top(r);
 472
 473         return 1;
 474 #else   /* BN_BITS!=32 */
 475         return 0;
 476 #endif
 477         }
 478
 479 #define nist_set_384(to,from,a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12) \
 480         { \
 481         if (a12 != 0) bn_cp_32(to, 0, from,  (a12) - 12) else bn_32_set_0(to, 0)\
 482         if (a11 != 0) bn_cp_32(to, 1, from,  (a11) - 12) else bn_32_set_0(to, 1)\
 483         if (a10 != 0) bn_cp_32(to, 2, from,  (a10) - 12) else bn_32_set_0(to, 2)\
 484         if (a9 != 0)  bn_cp_32(to, 3, from,  (a9) - 12)  else bn_32_set_0(to, 3)\
 485         if (a8 != 0)  bn_cp_32(to, 4, from,  (a8) - 12)  else bn_32_set_0(to, 4)\
 486         if (a7 != 0)  bn_cp_32(to, 5, from,  (a7) - 12)  else bn_32_set_0(to, 5)\
 487         if (a6 != 0)  bn_cp_32(to, 6, from,  (a6) - 12)  else bn_32_set_0(to, 6)\
 488         if (a5 != 0)  bn_cp_32(to, 7, from,  (a5) - 12)  else bn_32_set_0(to, 7)\
 489         if (a4 != 0)  bn_cp_32(to, 8, from,  (a4) - 12)  else bn_32_set_0(to, 8)\
 490         if (a3 != 0)  bn_cp_32(to, 9, from,  (a3) - 12)  else bn_32_set_0(to, 9)\
 491         if (a2 != 0)  bn_cp_32(to, 10, from, (a2) - 12)  else bn_32_set_0(to, 10)\
 492         if (a1 != 0)  bn_cp_32(to, 11, from, (a1) - 12)  else bn_32_set_0(to, 11)\
 493         }
 494
 495 int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 496         BN_CTX *ctx)
 497         {
 498 #if BN_BITS2 == 32
 499         int     i, top = a->top;
 500         int     carry = 0;
 501         register BN_ULONG *r_d, *a_d = a->d;
 502         BN_ULONG t_d[BN_NIST_384_TOP],
 503                  buf[BN_NIST_384_TOP],
 504                  c_d[BN_NIST_384_TOP],
 505                 *res;
 506         size_t   mask;
 507
 508         i = BN_ucmp(field, a);
 509         if (i == 0)
 510                 {
 511                 BN_zero(r);
 512                 return 1;
 513                 }
 514         else if (i > 0)
 515                 return (r == a)? 1 : (BN_copy(r ,a) != NULL);
 516
 517         if (top == BN_NIST_384_TOP)
 518                 return BN_usub(r, a, field);
 519
 520         if (r != a)
 521                 {
 522                 if (!bn_wexpand(r, BN_NIST_384_TOP))
 523                         return 0;
 524                 r_d = r->d;
 525                 nist_cp_bn(r_d, a_d, BN_NIST_384_TOP);
 526                 }
 527         else
 528                 r_d = a_d;
 529
 530         nist_cp_bn_0(buf, a_d + BN_NIST_384_TOP, top - BN_NIST_384_TOP, BN_NIST_384_TOP);
 531
 532         /*S1*/
 533         nist_set_256(t_d, buf, 0, 0, 0, 0, 0, 23-4, 22-4, 21-4);
 534                 /* left shift */
 535                 {
 536                 register BN_ULONG *ap,t,c;
 537                 ap = t_d;
 538                 c=0;
 539                 for (i = 3; i != 0; --i)
 540                         {
 541                         t= *ap;
 542                         *(ap++)=((t<<1)|c)&BN_MASK2;
 543                         c=(t & BN_TBIT)?1:0;
 544                         }
 545                 *ap=c;
 546                 }
 547         carry = bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2),
 548                 t_d, BN_NIST_256_TOP);
 549         /*
 550          * we need if (result>=modulus) subtract(result,modulus);
 551          * in n-bit space this can be expressed as
 552          * if (carry || result>=modulus) subtract(result,modulus);
 553          * the catch is that comparison implies subtraction and
 554          * therefore one can write tmp=subtract(result,modulus);
 555          * and then if(carry || !borrow) result=tmp; this's what
 556          * happens below, but without explicit if:-) a.
 557          */
 558         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 559         mask = ~mask | (0-(size_t)carry);
 560         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 561
 562         /*S2 */
 563         carry = bn_add_words(r_d, res, buf, BN_NIST_384_TOP);
 564         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 565         mask = ~mask | (0-(size_t)carry);
 566         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 567
 568         /*S3*/
 569         nist_set_384(t_d,buf,20,19,18,17,16,15,14,13,12,23,22,21);
 570         carry = bn_add_words(r_d, res, t_d, BN_NIST_384_TOP);
 571         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 572         mask = ~mask | (0-(size_t)carry);
 573         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 574
 575         /*S4*/
 576         nist_set_384(t_d,buf,19,18,17,16,15,14,13,12,20,0,23,0);
 577         carry = bn_add_words(r_d, res, t_d, BN_NIST_384_TOP);
 578         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 579         mask = ~mask | (0-(size_t)carry);
 580         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 581
 582         /*S5*/
 583         nist_set_384(t_d, buf,0,0,0,0,23,22,21,20,0,0,0,0);
 584         carry = bn_add_words(r_d, res, t_d, BN_NIST_384_TOP);
 585         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 586         mask = ~mask | (0-(size_t)carry);
 587         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 588
 589         /*S6*/
 590         nist_set_384(t_d,buf,0,0,0,0,0,0,23,22,21,0,0,20);
 591         carry = bn_add_words(r_d, res, t_d, BN_NIST_384_TOP);
 592         mask = 0-(size_t)bn_sub_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 593         mask = ~mask | (0-(size_t)carry);
 594         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 595
 596         /*D1*/
 597         nist_set_384(t_d,buf,22,21,20,19,18,17,16,15,14,13,12,23);
 598 #if BRANCH_FREE
 599         carry = bn_sub_words(r_d, res, t_d, BN_NIST_384_TOP);
 600         bn_add_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 601         mask = 0-(size_t)carry;
 602         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 603 #else
 604         if (bn_sub_words(r_d, res, t_d, BN_NIST_384_TOP))
 605                 bn_add_words(r_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 606 #endif
 607         /*D2*/
 608         nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,22,21,20,0);
 609 #if BRANCH_FREE
 610         carry = bn_sub_words(r_d, res, t_d, BN_NIST_384_TOP);
 611         bn_add_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 612         mask = 0-(size_t)carry;
 613         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 614 #else
 615         if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
 616                 bn_add_words(r_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 617 #endif
 618         /*D3*/
 619         nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,23,0,0,0);
 620 #if BRANCH_FREE
 621         carry = bn_sub_words(r_d, res, t_d, BN_NIST_384_TOP);
 622         bn_add_words(c_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 623         mask = 0-(size_t)carry;
 624         res = (BN_ULONG *)(((size_t)c_d&mask) | ((size_t)r_d&~mask));
 625
 626         nist_cp_bn(r_d, res, BN_NIST_384_TOP);
 627 #else
 628         if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
 629                 bn_add_words(r_d,r_d,_nist_p_384,BN_NIST_384_TOP);
 630 #endif
 631         r->top = BN_NIST_384_TOP;
 632         bn_correct_top(r);
 633
 634         return 1;
 635 #else   /* BN_BITS!=32 */
 636         return 0;
 637 #endif
 638         }
 639
 640 int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 641         BN_CTX *ctx)
 642         {
 643 #if BN_BITS2 == 64
 644 #define BN_NIST_521_TOP_MASK    (BN_ULONG)0x1FF
 645 #elif BN_BITS2 == 32
 646 #define BN_NIST_521_TOP_MASK    (BN_ULONG)0x1FF
 647 #endif
 648         int     top, ret = 0;
 649         BN_ULONG *r_d;
 650         BIGNUM  *tmp;
 651
 652         /* check whether a reduction is necessary */
 653         top = a->top;
 654         if (top < BN_NIST_521_TOP  || ( top == BN_NIST_521_TOP &&
 655            (!(a->d[BN_NIST_521_TOP-1] & ~(BN_NIST_521_TOP_MASK)))))
 656                 return (r == a)? 1 : (BN_copy(r ,a) != NULL);
 657
 658         BN_CTX_start(ctx);
 659         tmp = BN_CTX_get(ctx);
 660         if (!tmp)
 661                 goto err;
 662
 663         if (!bn_wexpand(tmp, BN_NIST_521_TOP))
 664                 goto err;
 665         nist_cp_bn(tmp->d, a->d, BN_NIST_521_TOP);
 666
 667         tmp->top = BN_NIST_521_TOP;
 668         tmp->d[BN_NIST_521_TOP-1]  &= BN_NIST_521_TOP_MASK;
 669         bn_correct_top(tmp);
 670
 671         if (!BN_rshift(r, a, 521))
 672                 goto err;
 673
 674         if (!BN_uadd(r, tmp, r))
 675                 goto err;
 676         top = r->top;
 677         r_d = r->d;
 678         if (top == BN_NIST_521_TOP  &&
 679            (r_d[BN_NIST_521_TOP-1] & ~(BN_NIST_521_TOP_MASK)))
 680                 {
 681                 BN_NIST_ADD_ONE(r_d)
 682                 r->d[BN_NIST_521_TOP-1] &= BN_NIST_521_TOP_MASK;
 683                 }
 684         bn_correct_top(r);
 685
 686         ret = 1;
 687 err:
 688         BN_CTX_end(ctx);
 689
 690         bn_check_top(r);
 691         return ret;
 692         }