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authorcvs2svn <admin@example.com>2001-04-23 15:30:26 +0000
committercvs2svn <admin@example.com>2001-04-23 15:30:26 +0000
commit5c517720d5b21a720e400586177c050d4bc95721 (patch)
tree34ec35b1061b27f8770c5ac5ee02aad558cbfc90 /src/lib/libcrypto/bn/bn_exp.c
parentd2092adc32c6de492232ba39518f9091db6bc67f (diff)
downloadopenbsd-OPENBSD_2_9_BASE.tar.gz
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This commit was manufactured by cvs2git to create tag 'OPENBSD_2_9_BASE'.OPENBSD_2_9_BASE
Diffstat (limited to 'src/lib/libcrypto/bn/bn_exp.c')
-rw-r--r--src/lib/libcrypto/bn/bn_exp.c696
1 files changed, 0 insertions, 696 deletions
diff --git a/src/lib/libcrypto/bn/bn_exp.c b/src/lib/libcrypto/bn/bn_exp.c
deleted file mode 100644
index d2c91628ac..0000000000
--- a/src/lib/libcrypto/bn/bn_exp.c
+++ /dev/null
@@ -1,696 +0,0 @@
1/* crypto/bn/bn_exp.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 * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
60 *
61 * Redistribution and use in source and binary forms, with or without
62 * modification, are permitted provided that the following conditions
63 * are met:
64 *
65 * 1. Redistributions of source code must retain the above copyright
66 * notice, this list of conditions and the following disclaimer.
67 *
68 * 2. Redistributions in binary form must reproduce the above copyright
69 * notice, this list of conditions and the following disclaimer in
70 * the documentation and/or other materials provided with the
71 * distribution.
72 *
73 * 3. All advertising materials mentioning features or use of this
74 * software must display the following acknowledgment:
75 * "This product includes software developed by the OpenSSL Project
76 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
77 *
78 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
79 * endorse or promote products derived from this software without
80 * prior written permission. For written permission, please contact
81 * openssl-core@openssl.org.
82 *
83 * 5. Products derived from this software may not be called "OpenSSL"
84 * nor may "OpenSSL" appear in their names without prior written
85 * permission of the OpenSSL Project.
86 *
87 * 6. Redistributions of any form whatsoever must retain the following
88 * acknowledgment:
89 * "This product includes software developed by the OpenSSL Project
90 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
91 *
92 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
93 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
94 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
95 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
96 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
97 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
98 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
99 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
100 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
101 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
102 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
103 * OF THE POSSIBILITY OF SUCH DAMAGE.
104 * ====================================================================
105 *
106 * This product includes cryptographic software written by Eric Young
107 * (eay@cryptsoft.com). This product includes software written by Tim
108 * Hudson (tjh@cryptsoft.com).
109 *
110 */
111
112
113#include <stdio.h>
114#include "cryptlib.h"
115#include "bn_lcl.h"
116
117#define TABLE_SIZE 32
118
119/* slow but works */
120int BN_mod_mul(BIGNUM *ret, BIGNUM *a, BIGNUM *b, const BIGNUM *m, BN_CTX *ctx)
121 {
122 BIGNUM *t;
123 int r=0;
124
125 bn_check_top(a);
126 bn_check_top(b);
127 bn_check_top(m);
128
129 BN_CTX_start(ctx);
130 if ((t = BN_CTX_get(ctx)) == NULL) goto err;
131 if (a == b)
132 { if (!BN_sqr(t,a,ctx)) goto err; }
133 else
134 { if (!BN_mul(t,a,b,ctx)) goto err; }
135 if (!BN_mod(ret,t,m,ctx)) goto err;
136 r=1;
137err:
138 BN_CTX_end(ctx);
139 return(r);
140 }
141
142
143/* this one works - simple but works */
144int BN_exp(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx)
145 {
146 int i,bits,ret=0;
147 BIGNUM *v,*rr;
148
149 BN_CTX_start(ctx);
150 if ((r == a) || (r == p))
151 rr = BN_CTX_get(ctx);
152 else
153 rr = r;
154 if ((v = BN_CTX_get(ctx)) == NULL) goto err;
155
156 if (BN_copy(v,a) == NULL) goto err;
157 bits=BN_num_bits(p);
158
159 if (BN_is_odd(p))
160 { if (BN_copy(rr,a) == NULL) goto err; }
161 else { if (!BN_one(rr)) goto err; }
162
163 for (i=1; i<bits; i++)
164 {
165 if (!BN_sqr(v,v,ctx)) goto err;
166 if (BN_is_bit_set(p,i))
167 {
168 if (!BN_mul(rr,rr,v,ctx)) goto err;
169 }
170 }
171 ret=1;
172err:
173 if (r != rr) BN_copy(r,rr);
174 BN_CTX_end(ctx);
175 return(ret);
176 }
177
178
179int BN_mod_exp(BIGNUM *r, BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
180 BN_CTX *ctx)
181 {
182 int ret;
183
184 bn_check_top(a);
185 bn_check_top(p);
186 bn_check_top(m);
187
188#ifdef MONT_MUL_MOD
189 /* I have finally been able to take out this pre-condition of
190 * the top bit being set. It was caused by an error in BN_div
191 * with negatives. There was also another problem when for a^b%m
192 * a >= m. eay 07-May-97 */
193/* if ((m->d[m->top-1]&BN_TBIT) && BN_is_odd(m)) */
194
195 if (BN_is_odd(m))
196 {
197 if (a->top == 1)
198 {
199 BN_ULONG A = a->d[0];
200 ret=BN_mod_exp_mont_word(r,A,p,m,ctx,NULL);
201 }
202 else
203 ret=BN_mod_exp_mont(r,a,p,m,ctx,NULL);
204 }
205 else
206#endif
207#ifdef RECP_MUL_MOD
208 { ret=BN_mod_exp_recp(r,a,p,m,ctx); }
209#else
210 { ret=BN_mod_exp_simple(r,a,p,m,ctx); }
211#endif
212
213 return(ret);
214 }
215
216
217int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
218 const BIGNUM *m, BN_CTX *ctx)
219 {
220 int i,j,bits,ret=0,wstart,wend,window,wvalue;
221 int start=1,ts=0;
222 BIGNUM *aa;
223 BIGNUM val[TABLE_SIZE];
224 BN_RECP_CTX recp;
225
226 bits=BN_num_bits(p);
227
228 if (bits == 0)
229 {
230 BN_one(r);
231 return(1);
232 }
233
234 BN_CTX_start(ctx);
235 if ((aa = BN_CTX_get(ctx)) == NULL) goto err;
236
237 BN_RECP_CTX_init(&recp);
238 if (BN_RECP_CTX_set(&recp,m,ctx) <= 0) goto err;
239
240 BN_init(&(val[0]));
241 ts=1;
242
243 if (!BN_mod(&(val[0]),a,m,ctx)) goto err; /* 1 */
244
245 window = BN_window_bits_for_exponent_size(bits);
246 if (window > 1)
247 {
248 if (!BN_mod_mul_reciprocal(aa,&(val[0]),&(val[0]),&recp,ctx))
249 goto err; /* 2 */
250 j=1<<(window-1);
251 for (i=1; i<j; i++)
252 {
253 BN_init(&val[i]);
254 if (!BN_mod_mul_reciprocal(&(val[i]),&(val[i-1]),aa,&recp,ctx))
255 goto err;
256 }
257 ts=i;
258 }
259
260 start=1; /* This is used to avoid multiplication etc
261 * when there is only the value '1' in the
262 * buffer. */
263 wvalue=0; /* The 'value' of the window */
264 wstart=bits-1; /* The top bit of the window */
265 wend=0; /* The bottom bit of the window */
266
267 if (!BN_one(r)) goto err;
268
269 for (;;)
270 {
271 if (BN_is_bit_set(p,wstart) == 0)
272 {
273 if (!start)
274 if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))
275 goto err;
276 if (wstart == 0) break;
277 wstart--;
278 continue;
279 }
280 /* We now have wstart on a 'set' bit, we now need to work out
281 * how bit a window to do. To do this we need to scan
282 * forward until the last set bit before the end of the
283 * window */
284 j=wstart;
285 wvalue=1;
286 wend=0;
287 for (i=1; i<window; i++)
288 {
289 if (wstart-i < 0) break;
290 if (BN_is_bit_set(p,wstart-i))
291 {
292 wvalue<<=(i-wend);
293 wvalue|=1;
294 wend=i;
295 }
296 }
297
298 /* wend is the size of the current window */
299 j=wend+1;
300 /* add the 'bytes above' */
301 if (!start)
302 for (i=0; i<j; i++)
303 {
304 if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx))
305 goto err;
306 }
307
308 /* wvalue will be an odd number < 2^window */
309 if (!BN_mod_mul_reciprocal(r,r,&(val[wvalue>>1]),&recp,ctx))
310 goto err;
311
312 /* move the 'window' down further */
313 wstart-=wend+1;
314 wvalue=0;
315 start=0;
316 if (wstart < 0) break;
317 }
318 ret=1;
319err:
320 BN_CTX_end(ctx);
321 for (i=0; i<ts; i++)
322 BN_clear_free(&(val[i]));
323 BN_RECP_CTX_free(&recp);
324 return(ret);
325 }
326
327
328int BN_mod_exp_mont(BIGNUM *rr, BIGNUM *a, const BIGNUM *p,
329 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
330 {
331 int i,j,bits,ret=0,wstart,wend,window,wvalue;
332 int start=1,ts=0;
333 BIGNUM *d,*r;
334 BIGNUM *aa;
335 BIGNUM val[TABLE_SIZE];
336 BN_MONT_CTX *mont=NULL;
337
338 bn_check_top(a);
339 bn_check_top(p);
340 bn_check_top(m);
341
342 if (!(m->d[0] & 1))
343 {
344 BNerr(BN_F_BN_MOD_EXP_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
345 return(0);
346 }
347 bits=BN_num_bits(p);
348 if (bits == 0)
349 {
350 BN_one(rr);
351 return(1);
352 }
353 BN_CTX_start(ctx);
354 d = BN_CTX_get(ctx);
355 r = BN_CTX_get(ctx);
356 if (d == NULL || r == NULL) goto err;
357
358 /* If this is not done, things will break in the montgomery
359 * part */
360
361 if (in_mont != NULL)
362 mont=in_mont;
363 else
364 {
365 if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
366 if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
367 }
368
369 BN_init(&val[0]);
370 ts=1;
371 if (BN_ucmp(a,m) >= 0)
372 {
373 if (!BN_mod(&(val[0]),a,m,ctx))
374 goto err;
375 aa= &(val[0]);
376 }
377 else
378 aa=a;
379 if (!BN_to_montgomery(&(val[0]),aa,mont,ctx)) goto err; /* 1 */
380
381 window = BN_window_bits_for_exponent_size(bits);
382 if (window > 1)
383 {
384 if (!BN_mod_mul_montgomery(d,&(val[0]),&(val[0]),mont,ctx)) goto err; /* 2 */
385 j=1<<(window-1);
386 for (i=1; i<j; i++)
387 {
388 BN_init(&(val[i]));
389 if (!BN_mod_mul_montgomery(&(val[i]),&(val[i-1]),d,mont,ctx))
390 goto err;
391 }
392 ts=i;
393 }
394
395 start=1; /* This is used to avoid multiplication etc
396 * when there is only the value '1' in the
397 * buffer. */
398 wvalue=0; /* The 'value' of the window */
399 wstart=bits-1; /* The top bit of the window */
400 wend=0; /* The bottom bit of the window */
401
402 if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
403 for (;;)
404 {
405 if (BN_is_bit_set(p,wstart) == 0)
406 {
407 if (!start)
408 {
409 if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
410 goto err;
411 }
412 if (wstart == 0) break;
413 wstart--;
414 continue;
415 }
416 /* We now have wstart on a 'set' bit, we now need to work out
417 * how bit a window to do. To do this we need to scan
418 * forward until the last set bit before the end of the
419 * window */
420 j=wstart;
421 wvalue=1;
422 wend=0;
423 for (i=1; i<window; i++)
424 {
425 if (wstart-i < 0) break;
426 if (BN_is_bit_set(p,wstart-i))
427 {
428 wvalue<<=(i-wend);
429 wvalue|=1;
430 wend=i;
431 }
432 }
433
434 /* wend is the size of the current window */
435 j=wend+1;
436 /* add the 'bytes above' */
437 if (!start)
438 for (i=0; i<j; i++)
439 {
440 if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
441 goto err;
442 }
443
444 /* wvalue will be an odd number < 2^window */
445 if (!BN_mod_mul_montgomery(r,r,&(val[wvalue>>1]),mont,ctx))
446 goto err;
447
448 /* move the 'window' down further */
449 wstart-=wend+1;
450 wvalue=0;
451 start=0;
452 if (wstart < 0) break;
453 }
454 if (!BN_from_montgomery(rr,r,mont,ctx)) goto err;
455 ret=1;
456err:
457 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
458 BN_CTX_end(ctx);
459 for (i=0; i<ts; i++)
460 BN_clear_free(&(val[i]));
461 return(ret);
462 }
463
464int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,
465 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
466 {
467 BN_MONT_CTX *mont = NULL;
468 int b, bits, ret=0;
469 int r_is_one;
470 BN_ULONG w, next_w;
471 BIGNUM *d, *r, *t;
472 BIGNUM *swap_tmp;
473#define BN_MOD_MUL_WORD(r, w, m) \
474 (BN_mul_word(r, (w)) && \
475 (/* BN_ucmp(r, (m)) < 0 ? 1 :*/ \
476 (BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1))))
477 /* BN_MOD_MUL_WORD is only used with 'w' large,
478 * so the BN_ucmp test is probably more overhead
479 * than always using BN_mod (which uses BN_copy if
480 * a similar test returns true). */
481#define BN_TO_MONTGOMERY_WORD(r, w, mont) \
482 (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx))
483
484 bn_check_top(p);
485 bn_check_top(m);
486
487 if (!(m->d[0] & 1))
488 {
489 BNerr(BN_F_BN_MOD_EXP_MONT_WORD,BN_R_CALLED_WITH_EVEN_MODULUS);
490 return(0);
491 }
492 bits = BN_num_bits(p);
493 if (bits == 0)
494 {
495 BN_one(rr);
496 return(1);
497 }
498 BN_CTX_start(ctx);
499 d = BN_CTX_get(ctx);
500 r = BN_CTX_get(ctx);
501 t = BN_CTX_get(ctx);
502 if (d == NULL || r == NULL || t == NULL) goto err;
503
504 if (in_mont != NULL)
505 mont=in_mont;
506 else
507 {
508 if ((mont = BN_MONT_CTX_new()) == NULL) goto err;
509 if (!BN_MONT_CTX_set(mont, m, ctx)) goto err;
510 }
511
512 r_is_one = 1; /* except for Montgomery factor */
513
514 /* bits-1 >= 0 */
515
516 /* The result is accumulated in the product r*w. */
517 w = a; /* bit 'bits-1' of 'p' is always set */
518 for (b = bits-2; b >= 0; b--)
519 {
520 /* First, square r*w. */
521 next_w = w*w;
522 if ((next_w/w) != w) /* overflow */
523 {
524 if (r_is_one)
525 {
526 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
527 r_is_one = 0;
528 }
529 else
530 {
531 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
532 }
533 next_w = 1;
534 }
535 w = next_w;
536 if (!r_is_one)
537 {
538 if (!BN_mod_mul_montgomery(r, r, r, mont, ctx)) goto err;
539 }
540
541 /* Second, multiply r*w by 'a' if exponent bit is set. */
542 if (BN_is_bit_set(p, b))
543 {
544 next_w = w*a;
545 if ((next_w/a) != w) /* overflow */
546 {
547 if (r_is_one)
548 {
549 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
550 r_is_one = 0;
551 }
552 else
553 {
554 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
555 }
556 next_w = a;
557 }
558 w = next_w;
559 }
560 }
561
562 /* Finally, set r:=r*w. */
563 if (w != 1)
564 {
565 if (r_is_one)
566 {
567 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) goto err;
568 r_is_one = 0;
569 }
570 else
571 {
572 if (!BN_MOD_MUL_WORD(r, w, m)) goto err;
573 }
574 }
575
576 if (r_is_one) /* can happen only if a == 1*/
577 {
578 if (!BN_one(rr)) goto err;
579 }
580 else
581 {
582 if (!BN_from_montgomery(rr, r, mont, ctx)) goto err;
583 }
584 ret = 1;
585err:
586 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
587 BN_CTX_end(ctx);
588 return(ret);
589 }
590
591
592/* The old fallback, simple version :-) */
593int BN_mod_exp_simple(BIGNUM *r, BIGNUM *a, BIGNUM *p, BIGNUM *m,
594 BN_CTX *ctx)
595 {
596 int i,j,bits,ret=0,wstart,wend,window,wvalue,ts=0;
597 int start=1;
598 BIGNUM *d;
599 BIGNUM val[TABLE_SIZE];
600
601 bits=BN_num_bits(p);
602
603 if (bits == 0)
604 {
605 BN_one(r);
606 return(1);
607 }
608
609 BN_CTX_start(ctx);
610 if ((d = BN_CTX_get(ctx)) == NULL) goto err;
611
612 BN_init(&(val[0]));
613 ts=1;
614 if (!BN_mod(&(val[0]),a,m,ctx)) goto err; /* 1 */
615
616 window = BN_window_bits_for_exponent_size(bits);
617 if (window > 1)
618 {
619 if (!BN_mod_mul(d,&(val[0]),&(val[0]),m,ctx))
620 goto err; /* 2 */
621 j=1<<(window-1);
622 for (i=1; i<j; i++)
623 {
624 BN_init(&(val[i]));
625 if (!BN_mod_mul(&(val[i]),&(val[i-1]),d,m,ctx))
626 goto err;
627 }
628 ts=i;
629 }
630
631 start=1; /* This is used to avoid multiplication etc
632 * when there is only the value '1' in the
633 * buffer. */
634 wvalue=0; /* The 'value' of the window */
635 wstart=bits-1; /* The top bit of the window */
636 wend=0; /* The bottom bit of the window */
637
638 if (!BN_one(r)) goto err;
639
640 for (;;)
641 {
642 if (BN_is_bit_set(p,wstart) == 0)
643 {
644 if (!start)
645 if (!BN_mod_mul(r,r,r,m,ctx))
646 goto err;
647 if (wstart == 0) break;
648 wstart--;
649 continue;
650 }
651 /* We now have wstart on a 'set' bit, we now need to work out
652 * how bit a window to do. To do this we need to scan
653 * forward until the last set bit before the end of the
654 * window */
655 j=wstart;
656 wvalue=1;
657 wend=0;
658 for (i=1; i<window; i++)
659 {
660 if (wstart-i < 0) break;
661 if (BN_is_bit_set(p,wstart-i))
662 {
663 wvalue<<=(i-wend);
664 wvalue|=1;
665 wend=i;
666 }
667 }
668
669 /* wend is the size of the current window */
670 j=wend+1;
671 /* add the 'bytes above' */
672 if (!start)
673 for (i=0; i<j; i++)
674 {
675 if (!BN_mod_mul(r,r,r,m,ctx))
676 goto err;
677 }
678
679 /* wvalue will be an odd number < 2^window */
680 if (!BN_mod_mul(r,r,&(val[wvalue>>1]),m,ctx))
681 goto err;
682
683 /* move the 'window' down further */
684 wstart-=wend+1;
685 wvalue=0;
686 start=0;
687 if (wstart < 0) break;
688 }
689 ret=1;
690err:
691 BN_CTX_end(ctx);
692 for (i=0; i<ts; i++)
693 BN_clear_free(&(val[i]));
694 return(ret);
695 }
696
generated by cgit v1.2.3-55-g6feb (git 2.39.1) at 2025-12-25 02:29:42 +0000