crypto/openssl-0.9.7e/crypto/bn/bn_lib.c

   1 /* crypto/bn/bn_lib.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 #ifndef BN_DEBUG
  60 # undef NDEBUG /* avoid conflicting definitions */
  61 # define NDEBUG
  62 #endif
  63
  64 #include <assert.h>
  65 #include <limits.h>
  66 #include <stdio.h>
  67 #include "cryptlib.h"
  68 #include "bn_lcl.h"
  69
  70 const char *BN_version="Big Number" OPENSSL_VERSION_PTEXT;
  71
  72 /* For a 32 bit machine
  73  * 2 -   4 ==  128
  74  * 3 -   8 ==  256
  75  * 4 -  16 ==  512
  76  * 5 -  32 == 1024
  77  * 6 -  64 == 2048
  78  * 7 - 128 == 4096
  79  * 8 - 256 == 8192
  80  */
  81 static int bn_limit_bits=0;
  82 static int bn_limit_num=8;        /* (1<<bn_limit_bits) */
  83 static int bn_limit_bits_low=0;
  84 static int bn_limit_num_low=8;    /* (1<<bn_limit_bits_low) */
  85 static int bn_limit_bits_high=0;
  86 static int bn_limit_num_high=8;   /* (1<<bn_limit_bits_high) */
  87 static int bn_limit_bits_mont=0;
  88 static int bn_limit_num_mont=8;   /* (1<<bn_limit_bits_mont) */
  89
  90 void BN_set_params(int mult, int high, int low, int mont)
  91         {
  92         if (mult >= 0)
  93                 {
  94                 if (mult > (sizeof(int)*8)-1)
  95                         mult=sizeof(int)*8-1;
  96                 bn_limit_bits=mult;
  97                 bn_limit_num=1<<mult;
  98                 }
  99         if (high >= 0)
 100                 {
 101                 if (high > (sizeof(int)*8)-1)
 102                         high=sizeof(int)*8-1;
 103                 bn_limit_bits_high=high;
 104                 bn_limit_num_high=1<<high;
 105                 }
 106         if (low >= 0)
 107                 {
 108                 if (low > (sizeof(int)*8)-1)
 109                         low=sizeof(int)*8-1;
 110                 bn_limit_bits_low=low;
 111                 bn_limit_num_low=1<<low;
 112                 }
 113         if (mont >= 0)
 114                 {
 115                 if (mont > (sizeof(int)*8)-1)
 116                         mont=sizeof(int)*8-1;
 117                 bn_limit_bits_mont=mont;
 118                 bn_limit_num_mont=1<<mont;
 119                 }
 120         }
 121
 122 int BN_get_params(int which)
 123         {
 124         if      (which == 0) return(bn_limit_bits);
 125         else if (which == 1) return(bn_limit_bits_high);
 126         else if (which == 2) return(bn_limit_bits_low);
 127         else if (which == 3) return(bn_limit_bits_mont);
 128         else return(0);
 129         }
 130
 131 const BIGNUM *BN_value_one(void)
 132         {
 133         static BN_ULONG data_one=1L;
 134         static BIGNUM const_one={&data_one,1,1,0};
 135
 136         return(&const_one);
 137         }
 138
 139 char *BN_options(void)
 140         {
 141         static int init=0;
 142         static char data[16];
 143
 144         if (!init)
 145                 {
 146                 init++;
 147 #ifdef BN_LLONG
 148                 BIO_snprintf(data,sizeof data,"bn(%d,%d)",
 149                              (int)sizeof(BN_ULLONG)*8,(int)sizeof(BN_ULONG)*8);
 150 #else
 151                 BIO_snprintf(data,sizeof data,"bn(%d,%d)",
 152                              (int)sizeof(BN_ULONG)*8,(int)sizeof(BN_ULONG)*8);
 153 #endif
 154                 }
 155         return(data);
 156         }
 157
 158 int BN_num_bits_word(BN_ULONG l)
 159         {
 160         static const char bits[256]={
 161                 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,
 162                 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
 163                 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
 164                 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
 165                 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 166                 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 167                 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 168                 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
 169                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
 170                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
 171                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
 172                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
 173                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
 174                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
 175                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
 176                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
 177                 };
 178
 179 #if defined(SIXTY_FOUR_BIT_LONG)
 180         if (l & 0xffffffff00000000L)
 181                 {
 182                 if (l & 0xffff000000000000L)
 183                         {
 184                         if (l & 0xff00000000000000L)
 185                                 {
 186                                 return(bits[(int)(l>>56)]+56);
 187                                 }
 188                         else    return(bits[(int)(l>>48)]+48);
 189                         }
 190                 else
 191                         {
 192                         if (l & 0x0000ff0000000000L)
 193                                 {
 194                                 return(bits[(int)(l>>40)]+40);
 195                                 }
 196                         else    return(bits[(int)(l>>32)]+32);
 197                         }
 198                 }
 199         else
 200 #else
 201 #ifdef SIXTY_FOUR_BIT
 202         if (l & 0xffffffff00000000LL)
 203                 {
 204                 if (l & 0xffff000000000000LL)
 205                         {
 206                         if (l & 0xff00000000000000LL)
 207                                 {
 208                                 return(bits[(int)(l>>56)]+56);
 209                                 }
 210                         else    return(bits[(int)(l>>48)]+48);
 211                         }
 212                 else
 213                         {
 214                         if (l & 0x0000ff0000000000LL)
 215                                 {
 216                                 return(bits[(int)(l>>40)]+40);
 217                                 }
 218                         else    return(bits[(int)(l>>32)]+32);
 219                         }
 220                 }
 221         else
 222 #endif
 223 #endif
 224                 {
 225 #if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
 226                 if (l & 0xffff0000L)
 227                         {
 228                         if (l & 0xff000000L)
 229                                 return(bits[(int)(l>>24L)]+24);
 230                         else    return(bits[(int)(l>>16L)]+16);
 231                         }
 232                 else
 233 #endif
 234                         {
 235 #if defined(SIXTEEN_BIT) || defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
 236                         if (l & 0xff00L)
 237                                 return(bits[(int)(l>>8)]+8);
 238                         else
 239 #endif
 240                                 return(bits[(int)(l   )]  );
 241                         }
 242                 }
 243         }
 244
 245 int BN_num_bits(const BIGNUM *a)
 246         {
 247         BN_ULONG l;
 248         int i;
 249
 250         bn_check_top(a);
 251
 252         if (a->top == 0) return(0);
 253         l=a->d[a->top-1];
 254         assert(l != 0);
 255         i=(a->top-1)*BN_BITS2;
 256         return(i+BN_num_bits_word(l));
 257         }
 258
 259 void BN_clear_free(BIGNUM *a)
 260         {
 261         int i;
 262
 263         if (a == NULL) return;
 264         if (a->d != NULL)
 265                 {
 266                 OPENSSL_cleanse(a->d,a->dmax*sizeof(a->d[0]));
 267                 if (!(BN_get_flags(a,BN_FLG_STATIC_DATA)))
 268                         OPENSSL_free(a->d);
 269                 }
 270         i=BN_get_flags(a,BN_FLG_MALLOCED);
 271         OPENSSL_cleanse(a,sizeof(BIGNUM));
 272         if (i)
 273                 OPENSSL_free(a);
 274         }
 275
 276 void BN_free(BIGNUM *a)
 277         {
 278         if (a == NULL) return;
 279         if ((a->d != NULL) && !(BN_get_flags(a,BN_FLG_STATIC_DATA)))
 280                 OPENSSL_free(a->d);
 281         a->flags|=BN_FLG_FREE; /* REMOVE? */
 282         if (a->flags & BN_FLG_MALLOCED)
 283                 OPENSSL_free(a);
 284         }
 285
 286 void BN_init(BIGNUM *a)
 287         {
 288         memset(a,0,sizeof(BIGNUM));
 289         }
 290
 291 BIGNUM *BN_new(void)
 292         {
 293         BIGNUM *ret;
 294
 295         if ((ret=(BIGNUM *)OPENSSL_malloc(sizeof(BIGNUM))) == NULL)
 296                 {
 297                 BNerr(BN_F_BN_NEW,ERR_R_MALLOC_FAILURE);
 298                 return(NULL);
 299                 }
 300         ret->flags=BN_FLG_MALLOCED;
 301         ret->top=0;
 302         ret->neg=0;
 303         ret->dmax=0;
 304         ret->d=NULL;
 305         return(ret);
 306         }
 307
 308 /* This is used both by bn_expand2() and bn_dup_expand() */
 309 /* The caller MUST check that words > b->dmax before calling this */
 310 static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
 311         {
 312         BN_ULONG *A,*a = NULL;
 313         const BN_ULONG *B;
 314         int i;
 315
 316         if (words > (INT_MAX/(4*BN_BITS2)))
 317                 {
 318                 BNerr(BN_F_BN_EXPAND_INTERNAL,BN_R_BIGNUM_TOO_LONG);
 319                 return NULL;
 320                 }
 321
 322         bn_check_top(b);
 323         if (BN_get_flags(b,BN_FLG_STATIC_DATA))
 324                 {
 325                 BNerr(BN_F_BN_EXPAND_INTERNAL,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
 326                 return(NULL);
 327                 }
 328         a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*(words+1));
 329         if (A == NULL)
 330                 {
 331                 BNerr(BN_F_BN_EXPAND_INTERNAL,ERR_R_MALLOC_FAILURE);
 332                 return(NULL);
 333                 }
 334 #if 1
 335         B=b->d;
 336         /* Check if the previous number needs to be copied */
 337         if (B != NULL)
 338                 {
 339                 for (i=b->top>>2; i>0; i--,A+=4,B+=4)
 340                         {
 341                         /*
 342                          * The fact that the loop is unrolled
 343                          * 4-wise is a tribute to Intel. It's
 344                          * the one that doesn't have enough
 345                          * registers to accomodate more data.
 346                          * I'd unroll it 8-wise otherwise:-)
 347                          *
 348                          *              <appro@fy.chalmers.se>
 349                          */
 350                         BN_ULONG a0,a1,a2,a3;
 351                         a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
 352                         A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
 353                         }
 354                 switch (b->top&3)
 355                         {
 356                 case 3: A[2]=B[2];
 357                 case 2: A[1]=B[1];
 358                 case 1: A[0]=B[0];
 359                 case 0: /* workaround for ultrix cc: without 'case 0', the optimizer does
 360                          * the switch table by doing a=top&3; a--; goto jump_table[a];
 361                          * which fails for top== 0 */
 362                         ;
 363                         }
 364                 }
 365
 366         /* Now need to zero any data between b->top and b->max */
 367         /* XXX Why? */
 368
 369         A= &(a[b->top]);
 370         for (i=(words - b->top)>>3; i>0; i--,A+=8)
 371                 {
 372                 A[0]=0; A[1]=0; A[2]=0; A[3]=0;
 373                 A[4]=0; A[5]=0; A[6]=0; A[7]=0;
 374                 }
 375         for (i=(words - b->top)&7; i>0; i--,A++)
 376                 A[0]=0;
 377 #else
 378         memset(A,0,sizeof(BN_ULONG)*(words+1));
 379         memcpy(A,b->d,sizeof(b->d[0])*b->top);
 380 #endif
 381
 382         return(a);
 383         }
 384
 385 /* This is an internal function that can be used instead of bn_expand2()
 386  * when there is a need to copy BIGNUMs instead of only expanding the
 387  * data part, while still expanding them.
 388  * Especially useful when needing to expand BIGNUMs that are declared
 389  * 'const' and should therefore not be changed.
 390  * The reason to use this instead of a BN_dup() followed by a bn_expand2()
 391  * is memory allocation overhead.  A BN_dup() followed by a bn_expand2()
 392  * will allocate new memory for the BIGNUM data twice, and free it once,
 393  * while bn_dup_expand() makes sure allocation is made only once.
 394  */
 395
 396 BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
 397         {
 398         BIGNUM *r = NULL;
 399
 400         /* This function does not work if
 401          *      words <= b->dmax && top < words
 402          * because BN_dup() does not preserve 'dmax'!
 403          * (But bn_dup_expand() is not used anywhere yet.)
 404          */
 405
 406         if (words > b->dmax)
 407                 {
 408                 BN_ULONG *a = bn_expand_internal(b, words);
 409
 410                 if (a)
 411                         {
 412                         r = BN_new();
 413                         if (r)
 414                                 {
 415                                 r->top = b->top;
 416                                 r->dmax = words;
 417                                 r->neg = b->neg;
 418                                 r->d = a;
 419                                 }
 420                         else
 421                                 {
 422                                 /* r == NULL, BN_new failure */
 423                                 OPENSSL_free(a);
 424                                 }
 425                         }
 426                 /* If a == NULL, there was an error in allocation in
 427                    bn_expand_internal(), and NULL should be returned */
 428                 }
 429         else
 430                 {
 431                 r = BN_dup(b);
 432                 }
 433
 434         return r;
 435         }
 436
 437 /* This is an internal function that should not be used in applications.
 438  * It ensures that 'b' has enough room for a 'words' word number number.
 439  * It is mostly used by the various BIGNUM routines. If there is an error,
 440  * NULL is returned. If not, 'b' is returned. */
 441
 442 BIGNUM *bn_expand2(BIGNUM *b, int words)
 443         {
 444         if (words > b->dmax)
 445                 {
 446                 BN_ULONG *a = bn_expand_internal(b, words);
 447
 448                 if (a)
 449                         {
 450                         if (b->d)
 451                                 OPENSSL_free(b->d);
 452                         b->d=a;
 453                         b->dmax=words;
 454                         }
 455                 else
 456                         b = NULL;
 457                 }
 458         return b;
 459         }
 460
 461 BIGNUM *BN_dup(const BIGNUM *a)
 462         {
 463         BIGNUM *r, *t;
 464
 465         if (a == NULL) return NULL;
 466
 467         bn_check_top(a);
 468
 469         t = BN_new();
 470         if (t == NULL) return(NULL);
 471         r = BN_copy(t, a);
 472         /* now  r == t || r == NULL */
 473         if (r == NULL)
 474                 BN_free(t);
 475         return r;
 476         }
 477
 478 BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
 479         {
 480         int i;
 481         BN_ULONG *A;
 482         const BN_ULONG *B;
 483
 484         bn_check_top(b);
 485
 486         if (a == b) return(a);
 487         if (bn_wexpand(a,b->top) == NULL) return(NULL);
 488
 489 #if 1
 490         A=a->d;
 491         B=b->d;
 492         for (i=b->top>>2; i>0; i--,A+=4,B+=4)
 493                 {
 494                 BN_ULONG a0,a1,a2,a3;
 495                 a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
 496                 A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
 497                 }
 498         switch (b->top&3)
 499                 {
 500                 case 3: A[2]=B[2];
 501                 case 2: A[1]=B[1];
 502                 case 1: A[0]=B[0];
 503                 case 0: ; /* ultrix cc workaround, see comments in bn_expand_internal */
 504                 }
 505 #else
 506         memcpy(a->d,b->d,sizeof(b->d[0])*b->top);
 507 #endif
 508
 509 /*      memset(&(a->d[b->top]),0,sizeof(a->d[0])*(a->max-b->top));*/
 510         a->top=b->top;
 511         if ((a->top == 0) && (a->d != NULL))
 512                 a->d[0]=0;
 513         a->neg=b->neg;
 514         return(a);
 515         }
 516
 517 void BN_swap(BIGNUM *a, BIGNUM *b)
 518         {
 519         int flags_old_a, flags_old_b;
 520         BN_ULONG *tmp_d;
 521         int tmp_top, tmp_dmax, tmp_neg;
 522
 523         flags_old_a = a->flags;
 524         flags_old_b = b->flags;
 525
 526         tmp_d = a->d;
 527         tmp_top = a->top;
 528         tmp_dmax = a->dmax;
 529         tmp_neg = a->neg;
 530
 531         a->d = b->d;
 532         a->top = b->top;
 533         a->dmax = b->dmax;
 534         a->neg = b->neg;
 535
 536         b->d = tmp_d;
 537         b->top = tmp_top;
 538         b->dmax = tmp_dmax;
 539         b->neg = tmp_neg;
 540
 541         a->flags = (flags_old_a & BN_FLG_MALLOCED) | (flags_old_b & BN_FLG_STATIC_DATA);
 542         b->flags = (flags_old_b & BN_FLG_MALLOCED) | (flags_old_a & BN_FLG_STATIC_DATA);
 543         }
 544
 545
 546 void BN_clear(BIGNUM *a)
 547         {
 548         if (a->d != NULL)
 549                 memset(a->d,0,a->dmax*sizeof(a->d[0]));
 550         a->top=0;
 551         a->neg=0;
 552         }
 553
 554 BN_ULONG BN_get_word(const BIGNUM *a)
 555         {
 556         int i,n;
 557         BN_ULONG ret=0;
 558
 559         n=BN_num_bytes(a);
 560         if (n > sizeof(BN_ULONG))
 561                 return(BN_MASK2);
 562         for (i=a->top-1; i>=0; i--)
 563                 {
 564 #ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */
 565                 ret<<=BN_BITS4; /* stops the compiler complaining */
 566                 ret<<=BN_BITS4;
 567 #else
 568                 ret=0;
 569 #endif
 570                 ret|=a->d[i];
 571                 }
 572         return(ret);
 573         }
 574
 575 int BN_set_word(BIGNUM *a, BN_ULONG w)
 576         {
 577         int i,n;
 578         if (bn_expand(a,sizeof(BN_ULONG)*8) == NULL) return(0);
 579
 580         n=sizeof(BN_ULONG)/BN_BYTES;
 581         a->neg=0;
 582         a->top=0;
 583         a->d[0]=(BN_ULONG)w&BN_MASK2;
 584         if (a->d[0] != 0) a->top=1;
 585         for (i=1; i<n; i++)
 586                 {
 587                 /* the following is done instead of
 588                  * w>>=BN_BITS2 so compilers don't complain
 589                  * on builds where sizeof(long) == BN_TYPES */
 590 #ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */
 591                 w>>=BN_BITS4;
 592                 w>>=BN_BITS4;
 593 #else
 594                 w=0;
 595 #endif
 596                 a->d[i]=(BN_ULONG)w&BN_MASK2;
 597                 if (a->d[i] != 0) a->top=i+1;
 598                 }
 599         return(1);
 600         }
 601
 602 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
 603         {
 604         unsigned int i,m;
 605         unsigned int n;
 606         BN_ULONG l;
 607
 608         if (ret == NULL) ret=BN_new();
 609         if (ret == NULL) return(NULL);
 610         l=0;
 611         n=len;
 612         if (n == 0)
 613                 {
 614                 ret->top=0;
 615                 return(ret);
 616                 }
 617         if (bn_expand(ret,(int)(n+2)*8) == NULL)
 618                 return(NULL);
 619         i=((n-1)/BN_BYTES)+1;
 620         m=((n-1)%(BN_BYTES));
 621         ret->top=i;
 622         ret->neg=0;
 623         while (n-- > 0)
 624                 {
 625                 l=(l<<8L)| *(s++);
 626                 if (m-- == 0)
 627                         {
 628                         ret->d[--i]=l;
 629                         l=0;
 630                         m=BN_BYTES-1;
 631                         }
 632                 }
 633         /* need to call this due to clear byte at top if avoiding
 634          * having the top bit set (-ve number) */
 635         bn_fix_top(ret);
 636         return(ret);
 637         }
 638
 639 /* ignore negative */
 640 int BN_bn2bin(const BIGNUM *a, unsigned char *to)
 641         {
 642         int n,i;
 643         BN_ULONG l;
 644
 645         n=i=BN_num_bytes(a);
 646         while (i-- > 0)
 647                 {
 648                 l=a->d[i/BN_BYTES];
 649                 *(to++)=(unsigned char)(l>>(8*(i%BN_BYTES)))&0xff;
 650                 }
 651         return(n);
 652         }
 653
 654 int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
 655         {
 656         int i;
 657         BN_ULONG t1,t2,*ap,*bp;
 658
 659         bn_check_top(a);
 660         bn_check_top(b);
 661
 662         i=a->top-b->top;
 663         if (i != 0) return(i);
 664         ap=a->d;
 665         bp=b->d;
 666         for (i=a->top-1; i>=0; i--)
 667                 {
 668                 t1= ap[i];
 669                 t2= bp[i];
 670                 if (t1 != t2)
 671                         return(t1 > t2?1:-1);
 672                 }
 673         return(0);
 674         }
 675
 676 int BN_cmp(const BIGNUM *a, const BIGNUM *b)
 677         {
 678         int i;
 679         int gt,lt;
 680         BN_ULONG t1,t2;
 681
 682         if ((a == NULL) || (b == NULL))
 683                 {
 684                 if (a != NULL)
 685                         return(-1);
 686                 else if (b != NULL)
 687                         return(1);
 688                 else
 689                         return(0);
 690                 }
 691
 692         bn_check_top(a);
 693         bn_check_top(b);
 694
 695         if (a->neg != b->neg)
 696                 {
 697                 if (a->neg)
 698                         return(-1);
 699                 else    return(1);
 700                 }
 701         if (a->neg == 0)
 702                 { gt=1; lt= -1; }
 703         else    { gt= -1; lt=1; }
 704
 705         if (a->top > b->top) return(gt);
 706         if (a->top < b->top) return(lt);
 707         for (i=a->top-1; i>=0; i--)
 708                 {
 709                 t1=a->d[i];
 710                 t2=b->d[i];
 711                 if (t1 > t2) return(gt);
 712                 if (t1 < t2) return(lt);
 713                 }
 714         return(0);
 715         }
 716
 717 int BN_set_bit(BIGNUM *a, int n)
 718         {
 719         int i,j,k;
 720
 721         i=n/BN_BITS2;
 722         j=n%BN_BITS2;
 723         if (a->top <= i)
 724                 {
 725                 if (bn_wexpand(a,i+1) == NULL) return(0);
 726                 for(k=a->top; k<i+1; k++)
 727                         a->d[k]=0;
 728                 a->top=i+1;
 729                 }
 730
 731         a->d[i]|=(((BN_ULONG)1)<<j);
 732         return(1);
 733         }
 734
 735 int BN_clear_bit(BIGNUM *a, int n)
 736         {
 737         int i,j;
 738
 739         i=n/BN_BITS2;
 740         j=n%BN_BITS2;
 741         if (a->top <= i) return(0);
 742
 743         a->d[i]&=(~(((BN_ULONG)1)<<j));
 744         bn_fix_top(a);
 745         return(1);
 746         }
 747
 748 int BN_is_bit_set(const BIGNUM *a, int n)
 749         {
 750         int i,j;
 751
 752         if (n < 0) return(0);
 753         i=n/BN_BITS2;
 754         j=n%BN_BITS2;
 755         if (a->top <= i) return(0);
 756         return((a->d[i]&(((BN_ULONG)1)<<j))?1:0);
 757         }
 758
 759 int BN_mask_bits(BIGNUM *a, int n)
 760         {
 761         int b,w;
 762
 763         w=n/BN_BITS2;
 764         b=n%BN_BITS2;
 765         if (w >= a->top) return(0);
 766         if (b == 0)
 767                 a->top=w;
 768         else
 769                 {
 770                 a->top=w+1;
 771                 a->d[w]&= ~(BN_MASK2<<b);
 772                 }
 773         bn_fix_top(a);
 774         return(1);
 775         }
 776
 777 int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
 778         {
 779         int i;
 780         BN_ULONG aa,bb;
 781
 782         aa=a[n-1];
 783         bb=b[n-1];
 784         if (aa != bb) return((aa > bb)?1:-1);
 785         for (i=n-2; i>=0; i--)
 786                 {
 787                 aa=a[i];
 788                 bb=b[i];
 789                 if (aa != bb) return((aa > bb)?1:-1);
 790                 }
 791         return(0);
 792         }
 793
 794 /* Here follows a specialised variants of bn_cmp_words().  It has the
 795    property of performing the operation on arrays of different sizes.
 796    The sizes of those arrays is expressed through cl, which is the
 797    common length ( basicall, min(len(a),len(b)) ), and dl, which is the
 798    delta between the two lengths, calculated as len(a)-len(b).
 799    All lengths are the number of BN_ULONGs...  */
 800
 801 int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b,
 802         int cl, int dl)
 803         {
 804         int n,i;
 805         n = cl-1;
 806
 807         if (dl < 0)
 808                 {
 809                 for (i=dl; i<0; i++)
 810                         {
 811                         if (b[n-i] != 0)
 812                                 return -1; /* a < b */
 813                         }
 814                 }
 815         if (dl > 0)
 816                 {
 817                 for (i=dl; i>0; i--)
 818                         {
 819                         if (a[n+i] != 0)
 820                                 return 1; /* a > b */
 821                         }
 822                 }
 823         return bn_cmp_words(a,b,cl);
 824         }