package/ead/src/tinysrp/bn_exp.c

   1 /* crypto/bn/bn_exp.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58 /* ====================================================================
  59  * Copyright (c) 1998-2000 The OpenSSL Project.  All rights reserved.
  60  *
  61  * Redistribution and use in source and binary forms, with or without
  62  * modification, are permitted provided that the following conditions
  63  * are met:
  64  *
  65  * 1. Redistributions of source code must retain the above copyright
  66  *    notice, this list of conditions and the following disclaimer.
  67  *
  68  * 2. Redistributions in binary form must reproduce the above copyright
  69  *    notice, this list of conditions and the following disclaimer in
  70  *    the documentation and/or other materials provided with the
  71  *    distribution.
  72  *
  73  * 3. All advertising materials mentioning features or use of this
  74  *    software must display the following acknowledgment:
  75  *    "This product includes software developed by the OpenSSL Project
  76  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  77  *
  78  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  79  *    endorse or promote products derived from this software without
  80  *    prior written permission. For written permission, please contact
  81  *    openssl-core@openssl.org.
  82  *
  83  * 5. Products derived from this software may not be called "OpenSSL"
  84  *    nor may "OpenSSL" appear in their names without prior written
  85  *    permission of the OpenSSL Project.
  86  *
  87  * 6. Redistributions of any form whatsoever must retain the following
  88  *    acknowledgment:
  89  *    "This product includes software developed by the OpenSSL Project
  90  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  91  *
  92  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  93  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  94  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  95  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  96  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  97  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  98  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  99  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 100  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 101  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 102  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 103  * OF THE POSSIBILITY OF SUCH DAMAGE.
 104  * ====================================================================
 105  *
 106  * This product includes cryptographic software written by Eric Young
 107  * (eay@cryptsoft.com).  This product includes software written by Tim
 108  * Hudson (tjh@cryptsoft.com).
 109  *
 110  */
 111
 112
 113 #include <stdio.h>
 114 #include "bn_lcl.h"
 115
 116 #define TABLE_SIZE      32
 117
 118 /* slow but works */
 119 int BN_mod_mul(BIGNUM *ret, BIGNUM *a, BIGNUM *b, const BIGNUM *m, BN_CTX *ctx)
 120         {
 121         BIGNUM *t;
 122         int r=0;
 123
 124         bn_check_top(a);
 125         bn_check_top(b);
 126         bn_check_top(m);
 127
 128         BN_CTX_start(ctx);
 129         if ((t = BN_CTX_get(ctx)) == NULL) goto err;
 130         if (a == b)
 131                 { if (!BN_sqr(t,a,ctx)) goto err; }
 132         else
 133                 { if (!BN_mul(t,a,b,ctx)) goto err; }
 134         if (!BN_mod(ret,t,m,ctx)) goto err;
 135         r=1;
 136 err:
 137         BN_CTX_end(ctx);
 138         return(r);
 139         }
 140
 141 int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
 142                BN_CTX *ctx)
 143         {
 144         int ret;
 145
 146         bn_check_top(a);
 147         bn_check_top(p);
 148         bn_check_top(m);
 149
 150 #ifdef MONT_MUL_MOD
 151         /* I have finally been able to take out this pre-condition of
 152          * the top bit being set.  It was caused by an error in BN_div
 153          * with negatives.  There was also another problem when for a^b%m
 154          * a >= m.  eay 07-May-97 */
 155 /*      if ((m->d[m->top-1]&BN_TBIT) && BN_is_odd(m)) */
 156
 157         if (BN_is_odd(m))
 158                 {
 159                 if (a->top == 1)
 160                         {
 161                         BN_ULONG A = a->d[0];
 162                         ret=BN_mod_exp_mont_word(r,A,p,m,ctx,NULL);
 163                         }
 164                 else
 165                         ret=BN_mod_exp_mont(r,a,p,m,ctx,NULL);
 166                 }
 167         else
 168 #endif
 169 #ifdef RECP_MUL_MOD
 170                 { ret=BN_mod_exp_recp(r,a,p,m,ctx); }
 171 #else
 172                 { ret=BN_mod_exp_simple(r,a,p,m,ctx); }
 173 #endif
 174
 175         return(ret);
 176         }
 177
 178
 179 #ifdef RECP_MUL_MOD
 180 int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 181                     const BIGNUM *m, BN_CTX *ctx)
 182         {
 183         int i,j,bits,ret=0,wstart,wend,window,wvalue;
 184         int start=1,ts=0;
 185         BIGNUM *aa;
 186         BIGNUM val[TABLE_SIZE];
 187         BN_RECP_CTX recp;
 188
 189         bits=BN_num_bits(p);
 190
 191         if (bits == 0)
 192                 {
 193                 BN_one(r);
 194                 return(1);
 195                 }
 196
 197         BN_CTX_start(ctx);
 198         if ((aa = BN_CTX_get(ctx)) == NULL) goto err;
 199
 200         BN_RECP_CTX_init(&recp);
 201         if (BN_RECP_CTX_set(&recp,m,ctx) <= 0) goto err;
 202
 203         BN_init(&(val[0]));
 204         ts=1;
 205
 206         if (!BN_mod(&(val[0]),a,m,ctx)) goto err;               /* 1 */
 207
 208         window = BN_window_bits_for_exponent_size(bits);
 209         if (window > 1)
 210                 {
 211                 if (!BN_mod_mul_reciprocal(aa,&(val[0]),&(val[0]),&recp,ctx))
 212                         goto err;                               /* 2 */
 213                 j=1<<(window-1);
 214                 for (i=1; i<j; i++)
 215                         {
 216                         BN_init(&val[i]);
 217                         if (!BN_mod_mul_reciprocal(&(val[i]),&(val[i-1]),aa,&recp,ctx))
 218                                 goto err;
 219                         }
 220                 ts=i;
 221                 }
 222
 223         start=1;        /* This is used to avoid multiplication etc
 224                          * when there is only the value '1' in the
 225                          * buffer. */
 226         wvalue=0;       /* The 'value' of the window */
 227         wstart=bits-1;  /* The top bit of the window */
 228         wend=0;         /* The bottom bit of the window */
 229
 230         if (!BN_one(r)) goto err;
 231
 232         for (;;)
 233                 {
 234                 if (BN_is_bit_set(p,wstart) == 0)
 235                         {
 236                         if (!start)
 237                                 if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))
 238                                 goto err;
 239                         if (wstart == 0) break;
 240                         wstart--;
 241                         continue;
 242                         }
 243                 /* We now have wstart on a 'set' bit, we now need to work out
 244                  * how bit a window to do.  To do this we need to scan
 245                  * forward until the last set bit before the end of the
 246                  * window */
 247                 j=wstart;
 248                 wvalue=1;
 249                 wend=0;
 250                 for (i=1; i<window; i++)
 251                         {
 252                         if (wstart-i < 0) break;
 253                         if (BN_is_bit_set(p,wstart-i))
 254                                 {
 255                                 wvalue<<=(i-wend);
 256                                 wvalue|=1;
 257                                 wend=i;
 258                                 }
 259                         }
 260
 261                 /* wend is the size of the current window */
 262                 j=wend+1;
 263                 /* add the 'bytes above' */
 264                 if (!start)
 265                         for (i=0; i<j; i++)
 266                                 {
 267                                 if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))
 268                                         goto err;
 269                                 }
 270
 271                 /* wvalue will be an odd number < 2^window */
 272                 if (!BN_mod_mul_reciprocal(r,r,&(val[wvalue>>1]),&recp,ctx))
 273                         goto err;
 274
 275                 /* move the 'window' down further */
 276                 wstart-=wend+1;
 277                 wvalue=0;
 278                 start=0;
 279                 if (wstart < 0) break;
 280                 }
 281         ret=1;
 282 err:
 283         BN_CTX_end(ctx);
 284         for (i=0; i<ts; i++)
 285                 BN_clear_free(&(val[i]));
 286         BN_RECP_CTX_free(&recp);
 287         return(ret);
 288         }
 289 #else
 290
 291 /* The old fallback, simple version :-) */
 292 int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 293              const BIGNUM *m, BN_CTX *ctx)
 294         {
 295         int i,j,bits,ret=0,wstart,wend,window,wvalue,ts=0;
 296         int start=1;
 297         BIGNUM *d;
 298         BIGNUM val[TABLE_SIZE];
 299
 300         bits=BN_num_bits(p);
 301
 302         if (bits == 0)
 303                 {
 304                 BN_one(r);
 305                 return(1);
 306                 }
 307
 308         BN_CTX_start(ctx);
 309         if ((d = BN_CTX_get(ctx)) == NULL) goto err;
 310
 311         BN_init(&(val[0]));
 312         ts=1;
 313         if (!BN_mod(&(val[0]),a,m,ctx)) goto err;               /* 1 */
 314
 315         window = BN_window_bits_for_exponent_size(bits);
 316         if (window > 1)
 317                 {
 318                 if (!BN_mod_mul(d,&(val[0]),&(val[0]),m,ctx))
 319                         goto err;                               /* 2 */
 320                 j=1<<(window-1);
 321                 for (i=1; i<j; i++)
 322                         {
 323                         BN_init(&(val[i]));
 324                         if (!BN_mod_mul(&(val[i]),&(val[i-1]),d,m,ctx))
 325                                 goto err;
 326                         }
 327                 ts=i;
 328                 }
 329
 330         start=1;        /* This is used to avoid multiplication etc
 331                          * when there is only the value '1' in the
 332                          * buffer. */
 333         wvalue=0;       /* The 'value' of the window */
 334         wstart=bits-1;  /* The top bit of the window */
 335         wend=0;         /* The bottom bit of the window */
 336
 337         if (!BN_one(r)) goto err;
 338
 339         for (;;)
 340                 {
 341                 if (BN_is_bit_set(p,wstart) == 0)
 342                         {
 343                         if (!start)
 344                                 if (!BN_mod_mul(r,r,r,m,ctx))
 345                                 goto err;
 346                         if (wstart == 0) break;
 347                         wstart--;
 348                         continue;
 349                         }
 350                 /* We now have wstart on a 'set' bit, we now need to work out
 351                  * how bit a window to do.  To do this we need to scan
 352                  * forward until the last set bit before the end of the
 353                  * window */
 354                 j=wstart;
 355                 wvalue=1;
 356                 wend=0;
 357                 for (i=1; i<window; i++)
 358                         {
 359                         if (wstart-i < 0) break;
 360                         if (BN_is_bit_set(p,wstart-i))
 361                                 {
 362                                 wvalue<<=(i-wend);
 363                                 wvalue|=1;
 364                                 wend=i;
 365                                 }
 366                         }
 367
 368                 /* wend is the size of the current window */
 369                 j=wend+1;
 370                 /* add the 'bytes above' */
 371                 if (!start)
 372                         for (i=0; i<j; i++)
 373                                 {
 374                                 if (!BN_mod_mul(r,r,r,m,ctx))
 375                                         goto err;
 376                                 }
 377
 378                 /* wvalue will be an odd number < 2^window */
 379                 if (!BN_mod_mul(r,r,&(val[wvalue>>1]),m,ctx))
 380                         goto err;
 381
 382                 /* move the 'window' down further */
 383                 wstart-=wend+1;
 384                 wvalue=0;
 385                 start=0;
 386                 if (wstart < 0) break;
 387                 }
 388         ret=1;
 389 err:
 390         BN_CTX_end(ctx);
 391         for (i=0; i<ts; i++)
 392                 BN_clear_free(&(val[i]));
 393         return(ret);
 394         }
 395 #endif