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 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 sprintf(data,"bn(%d,%d)",(int)sizeof(BN_ULLONG)*8, 149 (int)sizeof(BN_ULONG)*8); 150 #else 151 sprintf(data,"bn(%d,%d)",(int)sizeof(BN_ULONG)*8, 152 (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 memset(a->d,0,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 memset(a,0,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 an internal function that should not be used in applications. 309 * It ensures that 'b' has enough room for a 'words' word number number. 310 * It is mostly used by the various BIGNUM routines. If there is an error, 311 * NULL is returned. If not, 'b' is returned. */ 312 313 BIGNUM *bn_expand2(BIGNUM *b, int words) 314 { 315 BN_ULONG *A,*a; 316 const BN_ULONG *B; 317 int i; 318 319 bn_check_top(b); 320 321 if (words > b->dmax) 322 { 323 if (words > (INT_MAX/(4*BN_BITS2))) 324 { 325 BNerr(BN_F_BN_EXPAND2,BN_R_BIGNUM_TOO_LONG); 326 return NULL; 327 } 328 329 bn_check_top(b); 330 if (BN_get_flags(b,BN_FLG_STATIC_DATA)) 331 { 332 BNerr(BN_F_BN_EXPAND2,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA); 333 return(NULL); 334 } 335 a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*(words+1)); 336 if (A == NULL) 337 { 338 BNerr(BN_F_BN_EXPAND2,ERR_R_MALLOC_FAILURE); 339 return(NULL); 340 } 341 #if 1 342 B=b->d; 343 /* Check if the previous number needs to be copied */ 344 if (B != NULL) 345 { 346 #if 0 347 /* This lot is an unrolled loop to copy b->top 348 * BN_ULONGs from B to A 349 */ 350 /* 351 * I have nothing against unrolling but it's usually done for 352 * several reasons, namely: 353 * - minimize percentage of decision making code, i.e. branches; 354 * - avoid cache trashing; 355 * - make it possible to schedule loads earlier; 356 * Now let's examine the code below. The cornerstone of C is 357 * "programmer is always right" and that's what we love it for:-) 358 * For this very reason C compilers have to be paranoid when it 359 * comes to data aliasing and assume the worst. Yeah, but what 360 * does it mean in real life? This means that loop body below will 361 * be compiled to sequence of loads immediately followed by stores 362 * as compiler assumes the worst, something in A==B+1 style. As a 363 * result CPU pipeline is going to starve for incoming data. Secondly 364 * if A and B happen to share same cache line such code is going to 365 * cause severe cache trashing. Both factors have severe impact on 366 * performance of modern CPUs and this is the reason why this 367 * particular piece of code is #ifdefed away and replaced by more 368 * "friendly" version found in #else section below. This comment 369 * also applies to BN_copy function. 370 * 371 * <appro@fy.chalmers.se> 372 */ 373 for (i=b->top&(~7); i>0; i-=8) 374 { 375 A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3]; 376 A[4]=B[4]; A[5]=B[5]; A[6]=B[6]; A[7]=B[7]; 377 A+=8; 378 B+=8; 379 } 380 switch (b->top&7) 381 { 382 case 7: 383 A[6]=B[6]; 384 case 6: 385 A[5]=B[5]; 386 case 5: 387 A[4]=B[4]; 388 case 4: 389 A[3]=B[3]; 390 case 3: 391 A[2]=B[2]; 392 case 2: 393 A[1]=B[1]; 394 case 1: 395 A[0]=B[0]; 396 case 0: 397 /* I need the 'case 0' entry for utrix cc. 398 * If the optimizer is turned on, it does the 399 * switch table by doing 400 * a=top&7 401 * a--; 402 * goto jump_table[a]; 403 * If top is 0, this makes us jump to 0xffffffc 404 * which is rather bad :-(. 405 * eric 23-Apr-1998 406 */ 407 ; 408 } 409 #else 410 for (i=b->top>>2; i>0; i--,A+=4,B+=4) 411 { 412 /* 413 * The fact that the loop is unrolled 414 * 4-wise is a tribute to Intel. It's 415 * the one that doesn't have enough 416 * registers to accomodate more data. 417 * I'd unroll it 8-wise otherwise:-) 418 * 419 * <appro@fy.chalmers.se> 420 */ 421 BN_ULONG a0,a1,a2,a3; 422 a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3]; 423 A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3; 424 } 425 switch (b->top&3) 426 { 427 case 3: A[2]=B[2]; 428 case 2: A[1]=B[1]; 429 case 1: A[0]=B[0]; 430 case 0: ; /* ultrix cc workaround, see above */ 431 } 432 #endif 433 OPENSSL_free(b->d); 434 } 435 436 b->d=a; 437 b->dmax=words; 438 439 /* Now need to zero any data between b->top and b->max */ 440 441 A= &(b->d[b->top]); 442 for (i=(b->dmax - b->top)>>3; i>0; i--,A+=8) 443 { 444 A[0]=0; A[1]=0; A[2]=0; A[3]=0; 445 A[4]=0; A[5]=0; A[6]=0; A[7]=0; 446 } 447 for (i=(b->dmax - b->top)&7; i>0; i--,A++) 448 A[0]=0; 449 #else 450 memset(A,0,sizeof(BN_ULONG)*(words+1)); 451 memcpy(A,b->d,sizeof(b->d[0])*b->top); 452 b->d=a; 453 b->max=words; 454 #endif 455 456 /* memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG)); */ 457 /* { int i; for (i=b->max; i<words+1; i++) p[i]=i;} */ 458 459 } 460 return(b); 461 } 462 463 BIGNUM *BN_dup(const BIGNUM *a) 464 { 465 BIGNUM *r; 466 467 if (a == NULL) return NULL; 468 469 bn_check_top(a); 470 471 r=BN_new(); 472 if (r == NULL) return(NULL); 473 return((BIGNUM *)BN_copy(r,a)); 474 } 475 476 BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b) 477 { 478 int i; 479 BN_ULONG *A; 480 const BN_ULONG *B; 481 482 bn_check_top(b); 483 484 if (a == b) return(a); 485 if (bn_wexpand(a,b->top) == NULL) return(NULL); 486 487 #if 1 488 A=a->d; 489 B=b->d; 490 for (i=b->top>>2; i>0; i--,A+=4,B+=4) 491 { 492 BN_ULONG a0,a1,a2,a3; 493 a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3]; 494 A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3; 495 } 496 switch (b->top&3) 497 { 498 case 3: A[2]=B[2]; 499 case 2: A[1]=B[1]; 500 case 1: A[0]=B[0]; 501 case 0: ; /* ultrix cc workaround, see comments in bn_expand2 */ 502 } 503 #else 504 memcpy(a->d,b->d,sizeof(b->d[0])*b->top); 505 #endif 506 507 /* memset(&(a->d[b->top]),0,sizeof(a->d[0])*(a->max-b->top));*/ 508 a->top=b->top; 509 if ((a->top == 0) && (a->d != NULL)) 510 a->d[0]=0; 511 a->neg=b->neg; 512 return(a); 513 } 514 515 void BN_clear(BIGNUM *a) 516 { 517 if (a->d != NULL) 518 memset(a->d,0,a->dmax*sizeof(a->d[0])); 519 a->top=0; 520 a->neg=0; 521 } 522 523 BN_ULONG BN_get_word(BIGNUM *a) 524 { 525 int i,n; 526 BN_ULONG ret=0; 527 528 n=BN_num_bytes(a); 529 if (n > sizeof(BN_ULONG)) 530 return(BN_MASK2); 531 for (i=a->top-1; i>=0; i--) 532 { 533 #ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */ 534 ret<<=BN_BITS4; /* stops the compiler complaining */ 535 ret<<=BN_BITS4; 536 #else 537 ret=0; 538 #endif 539 ret|=a->d[i]; 540 } 541 return(ret); 542 } 543 544 int BN_set_word(BIGNUM *a, BN_ULONG w) 545 { 546 int i,n; 547 if (bn_expand(a,sizeof(BN_ULONG)*8) == NULL) return(0); 548 549 n=sizeof(BN_ULONG)/BN_BYTES; 550 a->neg=0; 551 a->top=0; 552 a->d[0]=(BN_ULONG)w&BN_MASK2; 553 if (a->d[0] != 0) a->top=1; 554 for (i=1; i<n; i++) 555 { 556 /* the following is done instead of 557 * w>>=BN_BITS2 so compilers don't complain 558 * on builds where sizeof(long) == BN_TYPES */ 559 #ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */ 560 w>>=BN_BITS4; 561 w>>=BN_BITS4; 562 #else 563 w=0; 564 #endif 565 a->d[i]=(BN_ULONG)w&BN_MASK2; 566 if (a->d[i] != 0) a->top=i+1; 567 } 568 return(1); 569 } 570 571 /* ignore negative */ 572 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret) 573 { 574 unsigned int i,m; 575 unsigned int n; 576 BN_ULONG l; 577 578 if (ret == NULL) ret=BN_new(); 579 if (ret == NULL) return(NULL); 580 l=0; 581 n=len; 582 if (n == 0) 583 { 584 ret->top=0; 585 return(ret); 586 } 587 if (bn_expand(ret,(int)(n+2)*8) == NULL) 588 return(NULL); 589 i=((n-1)/BN_BYTES)+1; 590 m=((n-1)%(BN_BYTES)); 591 ret->top=i; 592 while (n-- > 0) 593 { 594 l=(l<<8L)| *(s++); 595 if (m-- == 0) 596 { 597 ret->d[--i]=l; 598 l=0; 599 m=BN_BYTES-1; 600 } 601 } 602 /* need to call this due to clear byte at top if avoiding 603 * having the top bit set (-ve number) */ 604 bn_fix_top(ret); 605 return(ret); 606 } 607 608 /* ignore negative */ 609 int BN_bn2bin(const BIGNUM *a, unsigned char *to) 610 { 611 int n,i; 612 BN_ULONG l; 613 614 n=i=BN_num_bytes(a); 615 while (i-- > 0) 616 { 617 l=a->d[i/BN_BYTES]; 618 *(to++)=(unsigned char)(l>>(8*(i%BN_BYTES)))&0xff; 619 } 620 return(n); 621 } 622 623 int BN_ucmp(const BIGNUM *a, const BIGNUM *b) 624 { 625 int i; 626 BN_ULONG t1,t2,*ap,*bp; 627 628 bn_check_top(a); 629 bn_check_top(b); 630 631 i=a->top-b->top; 632 if (i != 0) return(i); 633 ap=a->d; 634 bp=b->d; 635 for (i=a->top-1; i>=0; i--) 636 { 637 t1= ap[i]; 638 t2= bp[i]; 639 if (t1 != t2) 640 return(t1 > t2?1:-1); 641 } 642 return(0); 643 } 644 645 int BN_cmp(const BIGNUM *a, const BIGNUM *b) 646 { 647 int i; 648 int gt,lt; 649 BN_ULONG t1,t2; 650 651 if ((a == NULL) || (b == NULL)) 652 { 653 if (a != NULL) 654 return(-1); 655 else if (b != NULL) 656 return(1); 657 else 658 return(0); 659 } 660 661 bn_check_top(a); 662 bn_check_top(b); 663 664 if (a->neg != b->neg) 665 { 666 if (a->neg) 667 return(-1); 668 else return(1); 669 } 670 if (a->neg == 0) 671 { gt=1; lt= -1; } 672 else { gt= -1; lt=1; } 673 674 if (a->top > b->top) return(gt); 675 if (a->top < b->top) return(lt); 676 for (i=a->top-1; i>=0; i--) 677 { 678 t1=a->d[i]; 679 t2=b->d[i]; 680 if (t1 > t2) return(gt); 681 if (t1 < t2) return(lt); 682 } 683 return(0); 684 } 685 686 int BN_set_bit(BIGNUM *a, int n) 687 { 688 int i,j,k; 689 690 i=n/BN_BITS2; 691 j=n%BN_BITS2; 692 if (a->top <= i) 693 { 694 if (bn_wexpand(a,i+1) == NULL) return(0); 695 for(k=a->top; k<i+1; k++) 696 a->d[k]=0; 697 a->top=i+1; 698 } 699 700 a->d[i]|=(((BN_ULONG)1)<<j); 701 return(1); 702 } 703 704 int BN_clear_bit(BIGNUM *a, int n) 705 { 706 int i,j; 707 708 i=n/BN_BITS2; 709 j=n%BN_BITS2; 710 if (a->top <= i) return(0); 711 712 a->d[i]&=(~(((BN_ULONG)1)<<j)); 713 bn_fix_top(a); 714 return(1); 715 } 716 717 int BN_is_bit_set(const BIGNUM *a, int n) 718 { 719 int i,j; 720 721 if (n < 0) return(0); 722 i=n/BN_BITS2; 723 j=n%BN_BITS2; 724 if (a->top <= i) return(0); 725 return((a->d[i]&(((BN_ULONG)1)<<j))?1:0); 726 } 727 728 int BN_mask_bits(BIGNUM *a, int n) 729 { 730 int b,w; 731 732 w=n/BN_BITS2; 733 b=n%BN_BITS2; 734 if (w >= a->top) return(0); 735 if (b == 0) 736 a->top=w; 737 else 738 { 739 a->top=w+1; 740 a->d[w]&= ~(BN_MASK2<<b); 741 } 742 bn_fix_top(a); 743 return(1); 744 } 745 746 int bn_cmp_words(BN_ULONG *a, BN_ULONG *b, int n) 747 { 748 int i; 749 BN_ULONG aa,bb; 750 751 aa=a[n-1]; 752 bb=b[n-1]; 753 if (aa != bb) return((aa > bb)?1:-1); 754 for (i=n-2; i>=0; i--) 755 { 756 aa=a[i]; 757 bb=b[i]; 758 if (aa != bb) return((aa > bb)?1:-1); 759 } 760 return(0); 761 } 762 763