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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
70const 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 */
83static int bn_limit_bits=0;
84static int bn_limit_num=8; /* (1<<bn_limit_bits) */
85static int bn_limit_bits_low=0;
86static int bn_limit_num_low=8; /* (1<<bn_limit_bits_low) */
87static int bn_limit_bits_high=0;
88static int bn_limit_num_high=8; /* (1<<bn_limit_bits_high) */
89static int bn_limit_bits_mont=0;
90static int bn_limit_num_mont=8; /* (1<<bn_limit_bits_mont) */
91
92void 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
124int 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
134const 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
142int 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
229int 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
238void 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
256void 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
273void BN_init(BIGNUM *a)
274 {
275 memset(a,0,sizeof(BIGNUM));
276 bn_check_top(a);
277 }
278
279BIGNUM *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 */
299static 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
375BIGNUM *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
426BIGNUM *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
460BIGNUM *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
478BIGNUM *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
515void 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
548void 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
557BN_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
567int 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
578BIGNUM *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 */
622int 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
637int 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
659int 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
700int 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
722int 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
738int 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
750int 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
771void 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
779int 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
803int 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 }
generated by cgit v1.2.3-55-g6feb (git 2.39.1) at 2025-04-03 03:47:15 +0000