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 /*-
75 * For a 32 bit machine
76 * 2 - 4 == 128
77 * 3 - 8 == 256
78 * 4 - 16 == 512
79 * 5 - 32 == 1024
80 * 6 - 64 == 2048
81 * 7 - 128 == 4096
82 * 8 - 256 == 8192
83 */
84 static int bn_limit_bits = 0;
85 static int bn_limit_num = 8; /* (1<<bn_limit_bits) */
86 static int bn_limit_bits_low = 0;
87 static int bn_limit_num_low = 8; /* (1<<bn_limit_bits_low) */
88 static int bn_limit_bits_high = 0;
89 static int bn_limit_num_high = 8; /* (1<<bn_limit_bits_high) */
90 static int bn_limit_bits_mont = 0;
91 static int bn_limit_num_mont = 8; /* (1<<bn_limit_bits_mont) */
92
BN_set_params(int mult,int high,int low,int mont)93 void BN_set_params(int mult, int high, int low, int mont)
94 {
95 if (mult >= 0) {
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 if (high > (int)(sizeof(int) * 8) - 1)
103 high = sizeof(int) * 8 - 1;
104 bn_limit_bits_high = high;
105 bn_limit_num_high = 1 << high;
106 }
107 if (low >= 0) {
108 if (low > (int)(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 if (mont > (int)(sizeof(int) * 8) - 1)
115 mont = sizeof(int) * 8 - 1;
116 bn_limit_bits_mont = mont;
117 bn_limit_num_mont = 1 << mont;
118 }
119 }
120
BN_get_params(int which)121 int BN_get_params(int which)
122 {
123 if (which == 0)
124 return (bn_limit_bits);
125 else if (which == 1)
126 return (bn_limit_bits_high);
127 else if (which == 2)
128 return (bn_limit_bits_low);
129 else if (which == 3)
130 return (bn_limit_bits_mont);
131 else
132 return (0);
133 }
134 #endif
135
BN_value_one(void)136 const BIGNUM *BN_value_one(void)
137 {
138 static const BN_ULONG data_one = 1L;
139 static const BIGNUM const_one =
140 { (BN_ULONG *)&data_one, 1, 1, 0, BN_FLG_STATIC_DATA };
141
142 return (&const_one);
143 }
144
BN_num_bits_word(BN_ULONG l)145 int BN_num_bits_word(BN_ULONG l)
146 {
147 static const unsigned char bits[256] = {
148 0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
149 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
150 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
151 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
152 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
153 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
154 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
155 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
162 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
163 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
164 };
165
166 #if defined(SIXTY_FOUR_BIT_LONG)
167 if (l & 0xffffffff00000000L) {
168 if (l & 0xffff000000000000L) {
169 if (l & 0xff00000000000000L) {
170 return (bits[(int)(l >> 56)] + 56);
171 } else
172 return (bits[(int)(l >> 48)] + 48);
173 } else {
174 if (l & 0x0000ff0000000000L) {
175 return (bits[(int)(l >> 40)] + 40);
176 } else
177 return (bits[(int)(l >> 32)] + 32);
178 }
179 } else
180 #else
181 # ifdef SIXTY_FOUR_BIT
182 if (l & 0xffffffff00000000LL) {
183 if (l & 0xffff000000000000LL) {
184 if (l & 0xff00000000000000LL) {
185 return (bits[(int)(l >> 56)] + 56);
186 } else
187 return (bits[(int)(l >> 48)] + 48);
188 } else {
189 if (l & 0x0000ff0000000000LL) {
190 return (bits[(int)(l >> 40)] + 40);
191 } else
192 return (bits[(int)(l >> 32)] + 32);
193 }
194 } else
195 # endif
196 #endif
197 {
198 #if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
199 if (l & 0xffff0000L) {
200 if (l & 0xff000000L)
201 return (bits[(int)(l >> 24L)] + 24);
202 else
203 return (bits[(int)(l >> 16L)] + 16);
204 } else
205 #endif
206 {
207 #if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
208 if (l & 0xff00L)
209 return (bits[(int)(l >> 8)] + 8);
210 else
211 #endif
212 return (bits[(int)(l)]);
213 }
214 }
215 }
216
BN_num_bits(const BIGNUM * a)217 int BN_num_bits(const BIGNUM *a)
218 {
219 int i = a->top - 1;
220 bn_check_top(a);
221
222 if (BN_is_zero(a))
223 return 0;
224 return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));
225 }
226
BN_clear_free(BIGNUM * a)227 void BN_clear_free(BIGNUM *a)
228 {
229 int i;
230
231 if (a == NULL)
232 return;
233 bn_check_top(a);
234 if (a->d != NULL) {
235 OPENSSL_cleanse(a->d, a->dmax * sizeof(a->d[0]));
236 if (!(BN_get_flags(a, BN_FLG_STATIC_DATA)))
237 OPENSSL_free(a->d);
238 }
239 i = BN_get_flags(a, BN_FLG_MALLOCED);
240 OPENSSL_cleanse(a, sizeof(BIGNUM));
241 if (i)
242 OPENSSL_free(a);
243 }
244
BN_free(BIGNUM * a)245 void BN_free(BIGNUM *a)
246 {
247 if (a == NULL)
248 return;
249 bn_check_top(a);
250 if ((a->d != NULL) && !(BN_get_flags(a, BN_FLG_STATIC_DATA)))
251 OPENSSL_free(a->d);
252 if (a->flags & BN_FLG_MALLOCED)
253 OPENSSL_free(a);
254 else {
255 #ifndef OPENSSL_NO_DEPRECATED
256 a->flags |= BN_FLG_FREE;
257 #endif
258 a->d = NULL;
259 }
260 }
261
BN_init(BIGNUM * a)262 void BN_init(BIGNUM *a)
263 {
264 memset(a, 0, sizeof(BIGNUM));
265 bn_check_top(a);
266 }
267
BN_new(void)268 BIGNUM *BN_new(void)
269 {
270 BIGNUM *ret;
271
272 if ((ret = (BIGNUM *)OPENSSL_malloc(sizeof(BIGNUM))) == NULL) {
273 BNerr(BN_F_BN_NEW, ERR_R_MALLOC_FAILURE);
274 return (NULL);
275 }
276 ret->flags = BN_FLG_MALLOCED;
277 ret->top = 0;
278 ret->neg = 0;
279 ret->dmax = 0;
280 ret->d = NULL;
281 bn_check_top(ret);
282 return (ret);
283 }
284
285 /* This is used both by bn_expand2() and bn_dup_expand() */
286 /* The caller MUST check that words > b->dmax before calling this */
bn_expand_internal(const BIGNUM * b,int words)287 static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
288 {
289 BN_ULONG *A, *a = NULL;
290 const BN_ULONG *B;
291 int i;
292
293 bn_check_top(b);
294
295 if (words > (INT_MAX / (4 * BN_BITS2))) {
296 BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_BIGNUM_TOO_LONG);
297 return NULL;
298 }
299 if (BN_get_flags(b, BN_FLG_STATIC_DATA)) {
300 BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
301 return (NULL);
302 }
303 a = A = (BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG) * words);
304 if (A == NULL) {
305 BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE);
306 return (NULL);
307 }
308 #ifdef PURIFY
309 /*
310 * Valgrind complains in BN_consttime_swap because we process the whole
311 * array even if it's not initialised yet. This doesn't matter in that
312 * function - what's important is constant time operation (we're not
313 * actually going to use the data)
314 */
315 memset(a, 0, sizeof(BN_ULONG) * words);
316 #endif
317
318 #if 1
319 B = b->d;
320 /* Check if the previous number needs to be copied */
321 if (B != NULL) {
322 for (i = b->top >> 2; i > 0; i--, A += 4, B += 4) {
323 /*
324 * The fact that the loop is unrolled
325 * 4-wise is a tribute to Intel. It's
326 * the one that doesn't have enough
327 * registers to accomodate more data.
328 * I'd unroll it 8-wise otherwise:-)
329 *
330 * <appro@fy.chalmers.se>
331 */
332 BN_ULONG a0, a1, a2, a3;
333 a0 = B[0];
334 a1 = B[1];
335 a2 = B[2];
336 a3 = B[3];
337 A[0] = a0;
338 A[1] = a1;
339 A[2] = a2;
340 A[3] = a3;
341 }
342 /*
343 * workaround for ultrix cc: without 'case 0', the optimizer does
344 * the switch table by doing a=top&3; a--; goto jump_table[a];
345 * which fails for top== 0
346 */
347 switch (b->top & 3) {
348 case 3:
349 A[2] = B[2];
350 case 2:
351 A[1] = B[1];
352 case 1:
353 A[0] = B[0];
354 case 0:
355 ;
356 }
357 }
358 #else
359 memset(A, 0, sizeof(BN_ULONG) * words);
360 memcpy(A, b->d, sizeof(b->d[0]) * b->top);
361 #endif
362
363 return (a);
364 }
365
366 /*
367 * This is an internal function that can be used instead of bn_expand2() when
368 * there is a need to copy BIGNUMs instead of only expanding the data part,
369 * while still expanding them. Especially useful when needing to expand
370 * BIGNUMs that are declared 'const' and should therefore not be changed. The
371 * reason to use this instead of a BN_dup() followed by a bn_expand2() is
372 * memory allocation overhead. A BN_dup() followed by a bn_expand2() will
373 * allocate new memory for the BIGNUM data twice, and free it once, while
374 * bn_dup_expand() makes sure allocation is made only once.
375 */
376
377 #ifndef OPENSSL_NO_DEPRECATED
bn_dup_expand(const BIGNUM * b,int words)378 BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
379 {
380 BIGNUM *r = NULL;
381
382 bn_check_top(b);
383
384 /*
385 * This function does not work if words <= b->dmax && top < words because
386 * BN_dup() does not preserve 'dmax'! (But bn_dup_expand() is not used
387 * anywhere yet.)
388 */
389
390 if (words > b->dmax) {
391 BN_ULONG *a = bn_expand_internal(b, words);
392
393 if (a) {
394 r = BN_new();
395 if (r) {
396 r->top = b->top;
397 r->dmax = words;
398 r->neg = b->neg;
399 r->d = a;
400 } else {
401 /* r == NULL, BN_new failure */
402 OPENSSL_free(a);
403 }
404 }
405 /*
406 * If a == NULL, there was an error in allocation in
407 * bn_expand_internal(), and NULL should be returned
408 */
409 } else {
410 r = BN_dup(b);
411 }
412
413 bn_check_top(r);
414 return r;
415 }
416 #endif
417
418 /*
419 * This is an internal function that should not be used in applications. It
420 * ensures that 'b' has enough room for a 'words' word number and initialises
421 * any unused part of b->d with leading zeros. It is mostly used by the
422 * various BIGNUM routines. If there is an error, NULL is returned. If not,
423 * 'b' is returned.
424 */
425
bn_expand2(BIGNUM * b,int words)426 BIGNUM *bn_expand2(BIGNUM *b, int words)
427 {
428 bn_check_top(b);
429
430 if (words > b->dmax) {
431 BN_ULONG *a = bn_expand_internal(b, words);
432 if (!a)
433 return NULL;
434 if (b->d)
435 OPENSSL_free(b->d);
436 b->d = a;
437 b->dmax = words;
438 }
439
440 /* None of this should be necessary because of what b->top means! */
441 #if 0
442 /*
443 * NB: bn_wexpand() calls this only if the BIGNUM really has to grow
444 */
445 if (b->top < b->dmax) {
446 int i;
447 BN_ULONG *A = &(b->d[b->top]);
448 for (i = (b->dmax - b->top) >> 3; i > 0; i--, A += 8) {
449 A[0] = 0;
450 A[1] = 0;
451 A[2] = 0;
452 A[3] = 0;
453 A[4] = 0;
454 A[5] = 0;
455 A[6] = 0;
456 A[7] = 0;
457 }
458 for (i = (b->dmax - b->top) & 7; i > 0; i--, A++)
459 A[0] = 0;
460 assert(A == &(b->d[b->dmax]));
461 }
462 #endif
463 bn_check_top(b);
464 return b;
465 }
466
BN_dup(const BIGNUM * a)467 BIGNUM *BN_dup(const BIGNUM *a)
468 {
469 BIGNUM *t;
470
471 if (a == NULL)
472 return NULL;
473 bn_check_top(a);
474
475 t = BN_new();
476 if (t == NULL)
477 return NULL;
478 if (!BN_copy(t, a)) {
479 BN_free(t);
480 return NULL;
481 }
482 bn_check_top(t);
483 return t;
484 }
485
BN_copy(BIGNUM * a,const BIGNUM * b)486 BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
487 {
488 int i;
489 BN_ULONG *A;
490 const BN_ULONG *B;
491
492 bn_check_top(b);
493
494 if (a == b)
495 return (a);
496 if (bn_wexpand(a, b->top) == NULL)
497 return (NULL);
498
499 #if 1
500 A = a->d;
501 B = b->d;
502 for (i = b->top >> 2; i > 0; i--, A += 4, B += 4) {
503 BN_ULONG a0, a1, a2, a3;
504 a0 = B[0];
505 a1 = B[1];
506 a2 = B[2];
507 a3 = B[3];
508 A[0] = a0;
509 A[1] = a1;
510 A[2] = a2;
511 A[3] = a3;
512 }
513 /* ultrix cc workaround, see comments in bn_expand_internal */
514 switch (b->top & 3) {
515 case 3:
516 A[2] = B[2];
517 case 2:
518 A[1] = B[1];
519 case 1:
520 A[0] = B[0];
521 case 0:;
522 }
523 #else
524 memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
525 #endif
526
527 a->top = b->top;
528 a->neg = b->neg;
529 bn_check_top(a);
530 return (a);
531 }
532
BN_swap(BIGNUM * a,BIGNUM * b)533 void BN_swap(BIGNUM *a, BIGNUM *b)
534 {
535 int flags_old_a, flags_old_b;
536 BN_ULONG *tmp_d;
537 int tmp_top, tmp_dmax, tmp_neg;
538
539 bn_check_top(a);
540 bn_check_top(b);
541
542 flags_old_a = a->flags;
543 flags_old_b = b->flags;
544
545 tmp_d = a->d;
546 tmp_top = a->top;
547 tmp_dmax = a->dmax;
548 tmp_neg = a->neg;
549
550 a->d = b->d;
551 a->top = b->top;
552 a->dmax = b->dmax;
553 a->neg = b->neg;
554
555 b->d = tmp_d;
556 b->top = tmp_top;
557 b->dmax = tmp_dmax;
558 b->neg = tmp_neg;
559
560 a->flags =
561 (flags_old_a & BN_FLG_MALLOCED) | (flags_old_b & BN_FLG_STATIC_DATA);
562 b->flags =
563 (flags_old_b & BN_FLG_MALLOCED) | (flags_old_a & BN_FLG_STATIC_DATA);
564 bn_check_top(a);
565 bn_check_top(b);
566 }
567
BN_clear(BIGNUM * a)568 void BN_clear(BIGNUM *a)
569 {
570 bn_check_top(a);
571 if (a->d != NULL)
572 memset(a->d, 0, a->dmax * sizeof(a->d[0]));
573 a->top = 0;
574 a->neg = 0;
575 }
576
BN_get_word(const BIGNUM * a)577 BN_ULONG BN_get_word(const BIGNUM *a)
578 {
579 if (a->top > 1)
580 return BN_MASK2;
581 else if (a->top == 1)
582 return a->d[0];
583 /* a->top == 0 */
584 return 0;
585 }
586
BN_set_word(BIGNUM * a,BN_ULONG w)587 int BN_set_word(BIGNUM *a, BN_ULONG w)
588 {
589 bn_check_top(a);
590 if (bn_expand(a, (int)sizeof(BN_ULONG) * 8) == NULL)
591 return (0);
592 a->neg = 0;
593 a->d[0] = w;
594 a->top = (w ? 1 : 0);
595 bn_check_top(a);
596 return (1);
597 }
598
BN_bin2bn(const unsigned char * s,int len,BIGNUM * ret)599 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
600 {
601 unsigned int i, m;
602 unsigned int n;
603 BN_ULONG l;
604 BIGNUM *bn = NULL;
605
606 if (ret == NULL)
607 ret = bn = BN_new();
608 if (ret == NULL)
609 return (NULL);
610 bn_check_top(ret);
611 l = 0;
612 n = len;
613 if (n == 0) {
614 ret->top = 0;
615 return (ret);
616 }
617 i = ((n - 1) / BN_BYTES) + 1;
618 m = ((n - 1) % (BN_BYTES));
619 if (bn_wexpand(ret, (int)i) == NULL) {
620 if (bn)
621 BN_free(bn);
622 return NULL;
623 }
624 ret->top = i;
625 ret->neg = 0;
626 while (n--) {
627 l = (l << 8L) | *(s++);
628 if (m-- == 0) {
629 ret->d[--i] = l;
630 l = 0;
631 m = BN_BYTES - 1;
632 }
633 }
634 /*
635 * need to call this due to clear byte at top if avoiding having the top
636 * bit set (-ve number)
637 */
638 bn_correct_top(ret);
639 return (ret);
640 }
641
642 /* ignore negative */
BN_bn2bin(const BIGNUM * a,unsigned char * to)643 int BN_bn2bin(const BIGNUM *a, unsigned char *to)
644 {
645 int n, i;
646 BN_ULONG l;
647
648 bn_check_top(a);
649 n = i = BN_num_bytes(a);
650 while (i--) {
651 l = a->d[i / BN_BYTES];
652 *(to++) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
653 }
654 return (n);
655 }
656
BN_ucmp(const BIGNUM * a,const BIGNUM * b)657 int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
658 {
659 int i;
660 BN_ULONG t1, t2, *ap, *bp;
661
662 bn_check_top(a);
663 bn_check_top(b);
664
665 i = a->top - b->top;
666 if (i != 0)
667 return (i);
668 ap = a->d;
669 bp = b->d;
670 for (i = a->top - 1; i >= 0; i--) {
671 t1 = ap[i];
672 t2 = bp[i];
673 if (t1 != t2)
674 return ((t1 > t2) ? 1 : -1);
675 }
676 return (0);
677 }
678
BN_cmp(const BIGNUM * a,const BIGNUM * b)679 int BN_cmp(const BIGNUM *a, const BIGNUM *b)
680 {
681 int i;
682 int gt, lt;
683 BN_ULONG t1, t2;
684
685 if ((a == NULL) || (b == NULL)) {
686 if (a != NULL)
687 return (-1);
688 else if (b != NULL)
689 return (1);
690 else
691 return (0);
692 }
693
694 bn_check_top(a);
695 bn_check_top(b);
696
697 if (a->neg != b->neg) {
698 if (a->neg)
699 return (-1);
700 else
701 return (1);
702 }
703 if (a->neg == 0) {
704 gt = 1;
705 lt = -1;
706 } else {
707 gt = -1;
708 lt = 1;
709 }
710
711 if (a->top > b->top)
712 return (gt);
713 if (a->top < b->top)
714 return (lt);
715 for (i = a->top - 1; i >= 0; i--) {
716 t1 = a->d[i];
717 t2 = b->d[i];
718 if (t1 > t2)
719 return (gt);
720 if (t1 < t2)
721 return (lt);
722 }
723 return (0);
724 }
725
BN_set_bit(BIGNUM * a,int n)726 int BN_set_bit(BIGNUM *a, int n)
727 {
728 int i, j, k;
729
730 if (n < 0)
731 return 0;
732
733 i = n / BN_BITS2;
734 j = n % BN_BITS2;
735 if (a->top <= i) {
736 if (bn_wexpand(a, i + 1) == NULL)
737 return (0);
738 for (k = a->top; k < i + 1; k++)
739 a->d[k] = 0;
740 a->top = i + 1;
741 }
742
743 a->d[i] |= (((BN_ULONG)1) << j);
744 bn_check_top(a);
745 return (1);
746 }
747
BN_clear_bit(BIGNUM * a,int n)748 int BN_clear_bit(BIGNUM *a, int n)
749 {
750 int i, j;
751
752 bn_check_top(a);
753 if (n < 0)
754 return 0;
755
756 i = n / BN_BITS2;
757 j = n % BN_BITS2;
758 if (a->top <= i)
759 return (0);
760
761 a->d[i] &= (~(((BN_ULONG)1) << j));
762 bn_correct_top(a);
763 return (1);
764 }
765
BN_is_bit_set(const BIGNUM * a,int n)766 int BN_is_bit_set(const BIGNUM *a, int n)
767 {
768 int i, j;
769
770 bn_check_top(a);
771 if (n < 0)
772 return 0;
773 i = n / BN_BITS2;
774 j = n % BN_BITS2;
775 if (a->top <= i)
776 return 0;
777 return (int)(((a->d[i]) >> j) & ((BN_ULONG)1));
778 }
779
BN_mask_bits(BIGNUM * a,int n)780 int BN_mask_bits(BIGNUM *a, int n)
781 {
782 int b, w;
783
784 bn_check_top(a);
785 if (n < 0)
786 return 0;
787
788 w = n / BN_BITS2;
789 b = n % BN_BITS2;
790 if (w >= a->top)
791 return 0;
792 if (b == 0)
793 a->top = w;
794 else {
795 a->top = w + 1;
796 a->d[w] &= ~(BN_MASK2 << b);
797 }
798 bn_correct_top(a);
799 return (1);
800 }
801
BN_set_negative(BIGNUM * a,int b)802 void BN_set_negative(BIGNUM *a, int b)
803 {
804 if (b && !BN_is_zero(a))
805 a->neg = 1;
806 else
807 a->neg = 0;
808 }
809
bn_cmp_words(const BN_ULONG * a,const BN_ULONG * b,int n)810 int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
811 {
812 int i;
813 BN_ULONG aa, bb;
814
815 aa = a[n - 1];
816 bb = b[n - 1];
817 if (aa != bb)
818 return ((aa > bb) ? 1 : -1);
819 for (i = n - 2; i >= 0; i--) {
820 aa = a[i];
821 bb = b[i];
822 if (aa != bb)
823 return ((aa > bb) ? 1 : -1);
824 }
825 return (0);
826 }
827
828 /*
829 * Here follows a specialised variants of bn_cmp_words(). It has the
830 * property of performing the operation on arrays of different sizes. The
831 * sizes of those arrays is expressed through cl, which is the common length
832 * ( basicall, min(len(a),len(b)) ), and dl, which is the delta between the
833 * two lengths, calculated as len(a)-len(b). All lengths are the number of
834 * BN_ULONGs...
835 */
836
bn_cmp_part_words(const BN_ULONG * a,const BN_ULONG * b,int cl,int dl)837 int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, int cl, int dl)
838 {
839 int n, i;
840 n = cl - 1;
841
842 if (dl < 0) {
843 for (i = dl; i < 0; i++) {
844 if (b[n - i] != 0)
845 return -1; /* a < b */
846 }
847 }
848 if (dl > 0) {
849 for (i = dl; i > 0; i--) {
850 if (a[n + i] != 0)
851 return 1; /* a > b */
852 }
853 }
854 return bn_cmp_words(a, b, cl);
855 }
856
857 /*
858 * Constant-time conditional swap of a and b.
859 * a and b are swapped if condition is not 0. The code assumes that at most one bit of condition is set.
860 * nwords is the number of words to swap. The code assumes that at least nwords are allocated in both a and b,
861 * and that no more than nwords are used by either a or b.
862 * a and b cannot be the same number
863 */
BN_consttime_swap(BN_ULONG condition,BIGNUM * a,BIGNUM * b,int nwords)864 void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
865 {
866 BN_ULONG t;
867 int i;
868
869 bn_wcheck_size(a, nwords);
870 bn_wcheck_size(b, nwords);
871
872 assert(a != b);
873 assert((condition & (condition - 1)) == 0);
874 assert(sizeof(BN_ULONG) >= sizeof(int));
875
876 condition = ((condition - 1) >> (BN_BITS2 - 1)) - 1;
877
878 t = (a->top ^ b->top) & condition;
879 a->top ^= t;
880 b->top ^= t;
881
882 #define BN_CONSTTIME_SWAP(ind) \
883 do { \
884 t = (a->d[ind] ^ b->d[ind]) & condition; \
885 a->d[ind] ^= t; \
886 b->d[ind] ^= t; \
887 } while (0)
888
889 switch (nwords) {
890 default:
891 for (i = 10; i < nwords; i++)
892 BN_CONSTTIME_SWAP(i);
893 /* Fallthrough */
894 case 10:
895 BN_CONSTTIME_SWAP(9); /* Fallthrough */
896 case 9:
897 BN_CONSTTIME_SWAP(8); /* Fallthrough */
898 case 8:
899 BN_CONSTTIME_SWAP(7); /* Fallthrough */
900 case 7:
901 BN_CONSTTIME_SWAP(6); /* Fallthrough */
902 case 6:
903 BN_CONSTTIME_SWAP(5); /* Fallthrough */
904 case 5:
905 BN_CONSTTIME_SWAP(4); /* Fallthrough */
906 case 4:
907 BN_CONSTTIME_SWAP(3); /* Fallthrough */
908 case 3:
909 BN_CONSTTIME_SWAP(2); /* Fallthrough */
910 case 2:
911 BN_CONSTTIME_SWAP(1); /* Fallthrough */
912 case 1:
913 BN_CONSTTIME_SWAP(0);
914 }
915 #undef BN_CONSTTIME_SWAP
916 }
917