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 /* This stuff appears to be completely unused, so is deprecated */ 73 #ifndef OPENSSL_NO_DEPRECATED 74 /* For a 32 bit machine 75 * 2 - 4 == 128 76 * 3 - 8 == 256 77 * 4 - 16 == 512 78 * 5 - 32 == 1024 79 * 6 - 64 == 2048 80 * 7 - 128 == 4096 81 * 8 - 256 == 8192 82 */ 83 static int bn_limit_bits=0; 84 static int bn_limit_num=8; /* (1<<bn_limit_bits) */ 85 static int bn_limit_bits_low=0; 86 static int bn_limit_num_low=8; /* (1<<bn_limit_bits_low) */ 87 static int bn_limit_bits_high=0; 88 static int bn_limit_num_high=8; /* (1<<bn_limit_bits_high) */ 89 static int bn_limit_bits_mont=0; 90 static int bn_limit_num_mont=8; /* (1<<bn_limit_bits_mont) */ 91 92 void BN_set_params(int mult, int high, int low, int mont) 93 { 94 if (mult >= 0) 95 { 96 if (mult > (int)(sizeof(int)*8)-1) 97 mult=sizeof(int)*8-1; 98 bn_limit_bits=mult; 99 bn_limit_num=1<<mult; 100 } 101 if (high >= 0) 102 { 103 if (high > (int)(sizeof(int)*8)-1) 104 high=sizeof(int)*8-1; 105 bn_limit_bits_high=high; 106 bn_limit_num_high=1<<high; 107 } 108 if (low >= 0) 109 { 110 if (low > (int)(sizeof(int)*8)-1) 111 low=sizeof(int)*8-1; 112 bn_limit_bits_low=low; 113 bn_limit_num_low=1<<low; 114 } 115 if (mont >= 0) 116 { 117 if (mont > (int)(sizeof(int)*8)-1) 118 mont=sizeof(int)*8-1; 119 bn_limit_bits_mont=mont; 120 bn_limit_num_mont=1<<mont; 121 } 122 } 123 124 int BN_get_params(int which) 125 { 126 if (which == 0) return(bn_limit_bits); 127 else if (which == 1) return(bn_limit_bits_high); 128 else if (which == 2) return(bn_limit_bits_low); 129 else if (which == 3) return(bn_limit_bits_mont); 130 else return(0); 131 } 132 #endif 133 134 const BIGNUM *BN_value_one(void) 135 { 136 static BN_ULONG data_one=1L; 137 static BIGNUM const_one={&data_one,1,1,0,BN_FLG_STATIC_DATA}; 138 139 return(&const_one); 140 } 141 142 int BN_num_bits_word(BN_ULONG l) 143 { 144 static const char bits[256]={ 145 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4, 146 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5, 147 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6, 148 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6, 149 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 150 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 151 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 152 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 153 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 154 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 155 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 156 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 157 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 158 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 159 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 160 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 161 }; 162 163 #if defined(SIXTY_FOUR_BIT_LONG) 164 if (l & 0xffffffff00000000L) 165 { 166 if (l & 0xffff000000000000L) 167 { 168 if (l & 0xff00000000000000L) 169 { 170 return(bits[(int)(l>>56)]+56); 171 } 172 else return(bits[(int)(l>>48)]+48); 173 } 174 else 175 { 176 if (l & 0x0000ff0000000000L) 177 { 178 return(bits[(int)(l>>40)]+40); 179 } 180 else return(bits[(int)(l>>32)]+32); 181 } 182 } 183 else 184 #else 185 #ifdef SIXTY_FOUR_BIT 186 if (l & 0xffffffff00000000LL) 187 { 188 if (l & 0xffff000000000000LL) 189 { 190 if (l & 0xff00000000000000LL) 191 { 192 return(bits[(int)(l>>56)]+56); 193 } 194 else return(bits[(int)(l>>48)]+48); 195 } 196 else 197 { 198 if (l & 0x0000ff0000000000LL) 199 { 200 return(bits[(int)(l>>40)]+40); 201 } 202 else return(bits[(int)(l>>32)]+32); 203 } 204 } 205 else 206 #endif 207 #endif 208 { 209 #if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG) 210 if (l & 0xffff0000L) 211 { 212 if (l & 0xff000000L) 213 return(bits[(int)(l>>24L)]+24); 214 else return(bits[(int)(l>>16L)]+16); 215 } 216 else 217 #endif 218 { 219 #if defined(SIXTEEN_BIT) || defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG) 220 if (l & 0xff00L) 221 return(bits[(int)(l>>8)]+8); 222 else 223 #endif 224 return(bits[(int)(l )] ); 225 } 226 } 227 } 228 229 int BN_num_bits(const BIGNUM *a) 230 { 231 int i = a->top - 1; 232 bn_check_top(a); 233 234 if (BN_is_zero(a)) return 0; 235 return ((i*BN_BITS2) + BN_num_bits_word(a->d[i])); 236 } 237 238 void BN_clear_free(BIGNUM *a) 239 { 240 int i; 241 242 if (a == NULL) return; 243 bn_check_top(a); 244 if (a->d != NULL) 245 { 246 OPENSSL_cleanse(a->d,a->dmax*sizeof(a->d[0])); 247 if (!(BN_get_flags(a,BN_FLG_STATIC_DATA))) 248 OPENSSL_free(a->d); 249 } 250 i=BN_get_flags(a,BN_FLG_MALLOCED); 251 OPENSSL_cleanse(a,sizeof(BIGNUM)); 252 if (i) 253 OPENSSL_free(a); 254 } 255 256 void BN_free(BIGNUM *a) 257 { 258 if (a == NULL) return; 259 bn_check_top(a); 260 if ((a->d != NULL) && !(BN_get_flags(a,BN_FLG_STATIC_DATA))) 261 OPENSSL_free(a->d); 262 if (a->flags & BN_FLG_MALLOCED) 263 OPENSSL_free(a); 264 else 265 { 266 #ifndef OPENSSL_NO_DEPRECATED 267 a->flags|=BN_FLG_FREE; 268 #endif 269 a->d = NULL; 270 } 271 } 272 273 void BN_init(BIGNUM *a) 274 { 275 memset(a,0,sizeof(BIGNUM)); 276 bn_check_top(a); 277 } 278 279 BIGNUM *BN_new(void) 280 { 281 BIGNUM *ret; 282 283 if ((ret=(BIGNUM *)OPENSSL_malloc(sizeof(BIGNUM))) == NULL) 284 { 285 BNerr(BN_F_BN_NEW,ERR_R_MALLOC_FAILURE); 286 return(NULL); 287 } 288 ret->flags=BN_FLG_MALLOCED; 289 ret->top=0; 290 ret->neg=0; 291 ret->dmax=0; 292 ret->d=NULL; 293 bn_check_top(ret); 294 return(ret); 295 } 296 297 /* This is used both by bn_expand2() and bn_dup_expand() */ 298 /* The caller MUST check that words > b->dmax before calling this */ 299 static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words) 300 { 301 BN_ULONG *A,*a = NULL; 302 const BN_ULONG *B; 303 int i; 304 305 bn_check_top(b); 306 307 if (words > (INT_MAX/(4*BN_BITS2))) 308 { 309 BNerr(BN_F_BN_EXPAND_INTERNAL,BN_R_BIGNUM_TOO_LONG); 310 return NULL; 311 } 312 if (BN_get_flags(b,BN_FLG_STATIC_DATA)) 313 { 314 BNerr(BN_F_BN_EXPAND_INTERNAL,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA); 315 return(NULL); 316 } 317 a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*words); 318 if (A == NULL) 319 { 320 BNerr(BN_F_BN_EXPAND_INTERNAL,ERR_R_MALLOC_FAILURE); 321 return(NULL); 322 } 323 #if 1 324 B=b->d; 325 /* Check if the previous number needs to be copied */ 326 if (B != NULL) 327 { 328 for (i=b->top>>2; i>0; i--,A+=4,B+=4) 329 { 330 /* 331 * The fact that the loop is unrolled 332 * 4-wise is a tribute to Intel. It's 333 * the one that doesn't have enough 334 * registers to accomodate more data. 335 * I'd unroll it 8-wise otherwise:-) 336 * 337 * <appro@fy.chalmers.se> 338 */ 339 BN_ULONG a0,a1,a2,a3; 340 a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3]; 341 A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3; 342 } 343 switch (b->top&3) 344 { 345 case 3: A[2]=B[2]; 346 case 2: A[1]=B[1]; 347 case 1: A[0]=B[0]; 348 case 0: /* workaround for ultrix cc: without 'case 0', the optimizer does 349 * the switch table by doing a=top&3; a--; goto jump_table[a]; 350 * which fails for top== 0 */ 351 ; 352 } 353 } 354 355 #else 356 memset(A,0,sizeof(BN_ULONG)*words); 357 memcpy(A,b->d,sizeof(b->d[0])*b->top); 358 #endif 359 360 return(a); 361 } 362 363 /* This is an internal function that can be used instead of bn_expand2() 364 * when there is a need to copy BIGNUMs instead of only expanding the 365 * data part, while still expanding them. 366 * Especially useful when needing to expand BIGNUMs that are declared 367 * 'const' and should therefore not be changed. 368 * The reason to use this instead of a BN_dup() followed by a bn_expand2() 369 * is memory allocation overhead. A BN_dup() followed by a bn_expand2() 370 * will allocate new memory for the BIGNUM data twice, and free it once, 371 * while bn_dup_expand() makes sure allocation is made only once. 372 */ 373 374 #ifndef OPENSSL_NO_DEPRECATED 375 BIGNUM *bn_dup_expand(const BIGNUM *b, int words) 376 { 377 BIGNUM *r = NULL; 378 379 bn_check_top(b); 380 381 /* This function does not work if 382 * words <= b->dmax && top < words 383 * because BN_dup() does not preserve 'dmax'! 384 * (But bn_dup_expand() is not used anywhere yet.) 385 */ 386 387 if (words > b->dmax) 388 { 389 BN_ULONG *a = bn_expand_internal(b, words); 390 391 if (a) 392 { 393 r = BN_new(); 394 if (r) 395 { 396 r->top = b->top; 397 r->dmax = words; 398 r->neg = b->neg; 399 r->d = a; 400 } 401 else 402 { 403 /* r == NULL, BN_new failure */ 404 OPENSSL_free(a); 405 } 406 } 407 /* If a == NULL, there was an error in allocation in 408 bn_expand_internal(), and NULL should be returned */ 409 } 410 else 411 { 412 r = BN_dup(b); 413 } 414 415 bn_check_top(r); 416 return r; 417 } 418 #endif 419 420 /* This is an internal function that should not be used in applications. 421 * It ensures that 'b' has enough room for a 'words' word number 422 * and initialises any unused part of b->d with leading zeros. 423 * It is mostly used by the various BIGNUM routines. If there is an error, 424 * NULL is returned. If not, 'b' is returned. */ 425 426 BIGNUM *bn_expand2(BIGNUM *b, int words) 427 { 428 bn_check_top(b); 429 430 if (words > b->dmax) 431 { 432 BN_ULONG *a = bn_expand_internal(b, words); 433 if(!a) return NULL; 434 if(b->d) OPENSSL_free(b->d); 435 b->d=a; 436 b->dmax=words; 437 } 438 439 /* None of this should be necessary because of what b->top means! */ 440 #if 0 441 /* NB: bn_wexpand() calls this only if the BIGNUM really has to grow */ 442 if (b->top < b->dmax) 443 { 444 int i; 445 BN_ULONG *A = &(b->d[b->top]); 446 for (i=(b->dmax - b->top)>>3; i>0; i--,A+=8) 447 { 448 A[0]=0; A[1]=0; A[2]=0; A[3]=0; 449 A[4]=0; A[5]=0; A[6]=0; A[7]=0; 450 } 451 for (i=(b->dmax - b->top)&7; i>0; i--,A++) 452 A[0]=0; 453 assert(A == &(b->d[b->dmax])); 454 } 455 #endif 456 bn_check_top(b); 457 return b; 458 } 459 460 BIGNUM *BN_dup(const BIGNUM *a) 461 { 462 BIGNUM *t; 463 464 if (a == NULL) return NULL; 465 bn_check_top(a); 466 467 t = BN_new(); 468 if (t == NULL) return NULL; 469 if(!BN_copy(t, a)) 470 { 471 BN_free(t); 472 return NULL; 473 } 474 bn_check_top(t); 475 return t; 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 a->top=b->top; 510 a->neg=b->neg; 511 bn_check_top(a); 512 return(a); 513 } 514 515 void BN_swap(BIGNUM *a, BIGNUM *b) 516 { 517 int flags_old_a, flags_old_b; 518 BN_ULONG *tmp_d; 519 int tmp_top, tmp_dmax, tmp_neg; 520 521 bn_check_top(a); 522 bn_check_top(b); 523 524 flags_old_a = a->flags; 525 flags_old_b = b->flags; 526 527 tmp_d = a->d; 528 tmp_top = a->top; 529 tmp_dmax = a->dmax; 530 tmp_neg = a->neg; 531 532 a->d = b->d; 533 a->top = b->top; 534 a->dmax = b->dmax; 535 a->neg = b->neg; 536 537 b->d = tmp_d; 538 b->top = tmp_top; 539 b->dmax = tmp_dmax; 540 b->neg = tmp_neg; 541 542 a->flags = (flags_old_a & BN_FLG_MALLOCED) | (flags_old_b & BN_FLG_STATIC_DATA); 543 b->flags = (flags_old_b & BN_FLG_MALLOCED) | (flags_old_a & BN_FLG_STATIC_DATA); 544 bn_check_top(a); 545 bn_check_top(b); 546 } 547 548 void BN_clear(BIGNUM *a) 549 { 550 bn_check_top(a); 551 if (a->d != NULL) 552 memset(a->d,0,a->dmax*sizeof(a->d[0])); 553 a->top=0; 554 a->neg=0; 555 } 556 557 BN_ULONG BN_get_word(const BIGNUM *a) 558 { 559 if (a->top > 1) 560 return BN_MASK2; 561 else if (a->top == 1) 562 return a->d[0]; 563 /* a->top == 0 */ 564 return 0; 565 } 566 567 int BN_set_word(BIGNUM *a, BN_ULONG w) 568 { 569 bn_check_top(a); 570 if (bn_expand(a,(int)sizeof(BN_ULONG)*8) == NULL) return(0); 571 a->neg = 0; 572 a->d[0] = w; 573 a->top = (w ? 1 : 0); 574 bn_check_top(a); 575 return(1); 576 } 577 578 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret) 579 { 580 unsigned int i,m; 581 unsigned int n; 582 BN_ULONG l; 583 BIGNUM *bn = NULL; 584 585 if (ret == NULL) 586 ret = bn = BN_new(); 587 if (ret == NULL) return(NULL); 588 bn_check_top(ret); 589 l=0; 590 n=len; 591 if (n == 0) 592 { 593 ret->top=0; 594 return(ret); 595 } 596 i=((n-1)/BN_BYTES)+1; 597 m=((n-1)%(BN_BYTES)); 598 if (bn_wexpand(ret, (int)i) == NULL) 599 { 600 if (bn) BN_free(bn); 601 return NULL; 602 } 603 ret->top=i; 604 ret->neg=0; 605 while (n--) 606 { 607 l=(l<<8L)| *(s++); 608 if (m-- == 0) 609 { 610 ret->d[--i]=l; 611 l=0; 612 m=BN_BYTES-1; 613 } 614 } 615 /* need to call this due to clear byte at top if avoiding 616 * having the top bit set (-ve number) */ 617 bn_correct_top(ret); 618 return(ret); 619 } 620 621 /* ignore negative */ 622 int BN_bn2bin(const BIGNUM *a, unsigned char *to) 623 { 624 int n,i; 625 BN_ULONG l; 626 627 bn_check_top(a); 628 n=i=BN_num_bytes(a); 629 while (i--) 630 { 631 l=a->d[i/BN_BYTES]; 632 *(to++)=(unsigned char)(l>>(8*(i%BN_BYTES)))&0xff; 633 } 634 return(n); 635 } 636 637 int BN_ucmp(const BIGNUM *a, const BIGNUM *b) 638 { 639 int i; 640 BN_ULONG t1,t2,*ap,*bp; 641 642 bn_check_top(a); 643 bn_check_top(b); 644 645 i=a->top-b->top; 646 if (i != 0) return(i); 647 ap=a->d; 648 bp=b->d; 649 for (i=a->top-1; i>=0; i--) 650 { 651 t1= ap[i]; 652 t2= bp[i]; 653 if (t1 != t2) 654 return((t1 > t2) ? 1 : -1); 655 } 656 return(0); 657 } 658 659 int BN_cmp(const BIGNUM *a, const BIGNUM *b) 660 { 661 int i; 662 int gt,lt; 663 BN_ULONG t1,t2; 664 665 if ((a == NULL) || (b == NULL)) 666 { 667 if (a != NULL) 668 return(-1); 669 else if (b != NULL) 670 return(1); 671 else 672 return(0); 673 } 674 675 bn_check_top(a); 676 bn_check_top(b); 677 678 if (a->neg != b->neg) 679 { 680 if (a->neg) 681 return(-1); 682 else return(1); 683 } 684 if (a->neg == 0) 685 { gt=1; lt= -1; } 686 else { gt= -1; lt=1; } 687 688 if (a->top > b->top) return(gt); 689 if (a->top < b->top) return(lt); 690 for (i=a->top-1; i>=0; i--) 691 { 692 t1=a->d[i]; 693 t2=b->d[i]; 694 if (t1 > t2) return(gt); 695 if (t1 < t2) return(lt); 696 } 697 return(0); 698 } 699 700 int BN_set_bit(BIGNUM *a, int n) 701 { 702 int i,j,k; 703 704 if (n < 0) 705 return 0; 706 707 i=n/BN_BITS2; 708 j=n%BN_BITS2; 709 if (a->top <= i) 710 { 711 if (bn_wexpand(a,i+1) == NULL) return(0); 712 for(k=a->top; k<i+1; k++) 713 a->d[k]=0; 714 a->top=i+1; 715 } 716 717 a->d[i]|=(((BN_ULONG)1)<<j); 718 bn_check_top(a); 719 return(1); 720 } 721 722 int BN_clear_bit(BIGNUM *a, int n) 723 { 724 int i,j; 725 726 bn_check_top(a); 727 if (n < 0) return 0; 728 729 i=n/BN_BITS2; 730 j=n%BN_BITS2; 731 if (a->top <= i) return(0); 732 733 a->d[i]&=(~(((BN_ULONG)1)<<j)); 734 bn_correct_top(a); 735 return(1); 736 } 737 738 int BN_is_bit_set(const BIGNUM *a, int n) 739 { 740 int i,j; 741 742 bn_check_top(a); 743 if (n < 0) return 0; 744 i=n/BN_BITS2; 745 j=n%BN_BITS2; 746 if (a->top <= i) return 0; 747 return(((a->d[i])>>j)&((BN_ULONG)1)); 748 } 749 750 int BN_mask_bits(BIGNUM *a, int n) 751 { 752 int b,w; 753 754 bn_check_top(a); 755 if (n < 0) return 0; 756 757 w=n/BN_BITS2; 758 b=n%BN_BITS2; 759 if (w >= a->top) return 0; 760 if (b == 0) 761 a->top=w; 762 else 763 { 764 a->top=w+1; 765 a->d[w]&= ~(BN_MASK2<<b); 766 } 767 bn_correct_top(a); 768 return(1); 769 } 770 771 void BN_set_negative(BIGNUM *a, int b) 772 { 773 if (b && !BN_is_zero(a)) 774 a->neg = 1; 775 else 776 a->neg = 0; 777 } 778 779 int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n) 780 { 781 int i; 782 BN_ULONG aa,bb; 783 784 aa=a[n-1]; 785 bb=b[n-1]; 786 if (aa != bb) return((aa > bb)?1:-1); 787 for (i=n-2; i>=0; i--) 788 { 789 aa=a[i]; 790 bb=b[i]; 791 if (aa != bb) return((aa > bb)?1:-1); 792 } 793 return(0); 794 } 795 796 /* Here follows a specialised variants of bn_cmp_words(). It has the 797 property of performing the operation on arrays of different sizes. 798 The sizes of those arrays is expressed through cl, which is the 799 common length ( basicall, min(len(a),len(b)) ), and dl, which is the 800 delta between the two lengths, calculated as len(a)-len(b). 801 All lengths are the number of BN_ULONGs... */ 802 803 int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, 804 int cl, int dl) 805 { 806 int n,i; 807 n = cl-1; 808 809 if (dl < 0) 810 { 811 for (i=dl; i<0; i++) 812 { 813 if (b[n-i] != 0) 814 return -1; /* a < b */ 815 } 816 } 817 if (dl > 0) 818 { 819 for (i=dl; i>0; i--) 820 { 821 if (a[n+i] != 0) 822 return 1; /* a > b */ 823 } 824 } 825 return bn_cmp_words(a,b,cl); 826 } 827