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d02b48c6 | 1 | /* crypto/bn/bn_exp.c */ |
58964a49 | 2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
d02b48c6 RE |
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 | #include <stdio.h> | |
60 | #include "cryptlib.h" | |
61 | #include "bn_lcl.h" | |
62 | ||
dfeab068 RE |
63 | #define TABLE_SIZE 16 |
64 | ||
d02b48c6 RE |
65 | /* slow but works */ |
66 | int BN_mod_mul(ret, a, b, m, ctx) | |
67 | BIGNUM *ret; | |
68 | BIGNUM *a; | |
69 | BIGNUM *b; | |
70 | BIGNUM *m; | |
71 | BN_CTX *ctx; | |
72 | { | |
73 | BIGNUM *t; | |
74 | int r=0; | |
75 | ||
dfeab068 RE |
76 | bn_check_top(a); |
77 | bn_check_top(b); | |
78 | bn_check_top(m); | |
79 | ||
80 | t= &(ctx->bn[ctx->tos++]); | |
d02b48c6 RE |
81 | if (a == b) |
82 | { if (!BN_sqr(t,a,ctx)) goto err; } | |
83 | else | |
dfeab068 | 84 | { if (!BN_mul(t,a,b,ctx)) goto err; } |
d02b48c6 RE |
85 | if (!BN_mod(ret,t,m,ctx)) goto err; |
86 | r=1; | |
87 | err: | |
88 | ctx->tos--; | |
89 | return(r); | |
90 | } | |
91 | ||
92 | #if 0 | |
93 | /* this one works - simple but works */ | |
94 | int BN_mod_exp(r,a,p,m,ctx) | |
95 | BIGNUM *r,*a,*p,*m; | |
96 | BN_CTX *ctx; | |
97 | { | |
98 | int i,bits,ret=0; | |
99 | BIGNUM *v,*tmp; | |
100 | ||
dfeab068 RE |
101 | v= &(ctx->bn[ctx->tos++]); |
102 | tmp= &(ctx->bn[ctx->tos++]); | |
d02b48c6 RE |
103 | |
104 | if (BN_copy(v,a) == NULL) goto err; | |
105 | bits=BN_num_bits(p); | |
106 | ||
107 | if (BN_is_odd(p)) | |
108 | { if (BN_copy(r,a) == NULL) goto err; } | |
109 | else { if (BN_one(r)) goto err; } | |
110 | ||
111 | for (i=1; i<bits; i++) | |
112 | { | |
113 | if (!BN_sqr(tmp,v,ctx)) goto err; | |
114 | if (!BN_mod(v,tmp,m,ctx)) goto err; | |
115 | if (BN_is_bit_set(p,i)) | |
116 | { | |
dfeab068 | 117 | if (!BN_mul(tmp,r,v,ctx)) goto err; |
d02b48c6 RE |
118 | if (!BN_mod(r,tmp,m,ctx)) goto err; |
119 | } | |
120 | } | |
121 | ret=1; | |
122 | err: | |
123 | ctx->tos-=2; | |
124 | return(ret); | |
125 | } | |
126 | ||
127 | #endif | |
128 | ||
58964a49 RE |
129 | /* this one works - simple but works */ |
130 | int BN_exp(r,a,p,ctx) | |
131 | BIGNUM *r,*a,*p; | |
132 | BN_CTX *ctx; | |
133 | { | |
134 | int i,bits,ret=0; | |
135 | BIGNUM *v,*tmp; | |
136 | ||
dfeab068 RE |
137 | v= &(ctx->bn[ctx->tos++]); |
138 | tmp= &(ctx->bn[ctx->tos++]); | |
58964a49 RE |
139 | |
140 | if (BN_copy(v,a) == NULL) goto err; | |
141 | bits=BN_num_bits(p); | |
142 | ||
143 | if (BN_is_odd(p)) | |
144 | { if (BN_copy(r,a) == NULL) goto err; } | |
145 | else { if (BN_one(r)) goto err; } | |
146 | ||
147 | for (i=1; i<bits; i++) | |
148 | { | |
149 | if (!BN_sqr(tmp,v,ctx)) goto err; | |
150 | if (BN_is_bit_set(p,i)) | |
151 | { | |
dfeab068 | 152 | if (!BN_mul(tmp,r,v,ctx)) goto err; |
58964a49 RE |
153 | } |
154 | } | |
155 | ret=1; | |
156 | err: | |
157 | ctx->tos-=2; | |
158 | return(ret); | |
159 | } | |
160 | ||
d02b48c6 RE |
161 | int BN_mod_exp(r,a,p,m,ctx) |
162 | BIGNUM *r; | |
163 | BIGNUM *a; | |
164 | BIGNUM *p; | |
165 | BIGNUM *m; | |
166 | BN_CTX *ctx; | |
167 | { | |
168 | int ret; | |
169 | ||
dfeab068 RE |
170 | bn_check_top(a); |
171 | bn_check_top(p); | |
172 | bn_check_top(m); | |
173 | ||
d02b48c6 RE |
174 | #ifdef MONT_MUL_MOD |
175 | /* I have finally been able to take out this pre-condition of | |
176 | * the top bit being set. It was caused by an error in BN_div | |
177 | * with negatives. There was also another problem when for a^b%m | |
178 | * a >= m. eay 07-May-97 */ | |
179 | /* if ((m->d[m->top-1]&BN_TBIT) && BN_is_odd(m)) */ | |
180 | ||
181 | if (BN_is_odd(m)) | |
58964a49 | 182 | { ret=BN_mod_exp_mont(r,a,p,m,ctx,NULL); } |
d02b48c6 RE |
183 | else |
184 | #endif | |
185 | #ifdef RECP_MUL_MOD | |
186 | { ret=BN_mod_exp_recp(r,a,p,m,ctx); } | |
187 | #else | |
188 | { ret=BN_mod_exp_simple(r,a,p,m,ctx); } | |
189 | #endif | |
190 | ||
191 | return(ret); | |
192 | } | |
193 | ||
194 | /* #ifdef RECP_MUL_MOD */ | |
195 | int BN_mod_exp_recp(r,a,p,m,ctx) | |
196 | BIGNUM *r; | |
197 | BIGNUM *a; | |
198 | BIGNUM *p; | |
199 | BIGNUM *m; | |
200 | BN_CTX *ctx; | |
201 | { | |
dfeab068 RE |
202 | int i,j,bits,ret=0,wstart,wend,window,wvalue; |
203 | int start=1,ts=0; | |
204 | BIGNUM *aa; | |
205 | BIGNUM val[TABLE_SIZE]; | |
206 | BN_RECP_CTX recp; | |
d02b48c6 | 207 | |
dfeab068 | 208 | aa= &(ctx->bn[ctx->tos++]); |
d02b48c6 RE |
209 | bits=BN_num_bits(p); |
210 | ||
211 | if (bits == 0) | |
212 | { | |
213 | BN_one(r); | |
214 | return(1); | |
215 | } | |
dfeab068 RE |
216 | BN_RECP_CTX_init(&recp); |
217 | if (BN_RECP_CTX_set(&recp,m,ctx) <= 0) goto err; | |
218 | ||
219 | BN_init(&(val[0])); | |
220 | ts=1; | |
d02b48c6 | 221 | |
dfeab068 RE |
222 | if (!BN_mod(&(val[0]),a,m,ctx)) goto err; /* 1 */ |
223 | if (!BN_mod_mul_reciprocal(aa,&(val[0]),&(val[0]),&recp,ctx)) | |
d02b48c6 RE |
224 | goto err; /* 2 */ |
225 | ||
226 | if (bits <= 17) /* This is probably 3 or 0x10001, so just do singles */ | |
227 | window=1; | |
228 | else if (bits >= 256) | |
229 | window=5; /* max size of window */ | |
230 | else if (bits >= 128) | |
231 | window=4; | |
232 | else | |
233 | window=3; | |
234 | ||
235 | j=1<<(window-1); | |
236 | for (i=1; i<j; i++) | |
237 | { | |
dfeab068 RE |
238 | BN_init(&val[i]); |
239 | if (!BN_mod_mul_reciprocal(&(val[i]),&(val[i-1]),aa,&recp,ctx)) | |
d02b48c6 RE |
240 | goto err; |
241 | } | |
dfeab068 | 242 | ts=i; |
d02b48c6 RE |
243 | |
244 | start=1; /* This is used to avoid multiplication etc | |
245 | * when there is only the value '1' in the | |
246 | * buffer. */ | |
247 | wvalue=0; /* The 'value' of the window */ | |
248 | wstart=bits-1; /* The top bit of the window */ | |
249 | wend=0; /* The bottom bit of the window */ | |
250 | ||
251 | if (!BN_one(r)) goto err; | |
252 | ||
253 | for (;;) | |
254 | { | |
255 | if (BN_is_bit_set(p,wstart) == 0) | |
256 | { | |
257 | if (!start) | |
dfeab068 | 258 | if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx)) |
d02b48c6 RE |
259 | goto err; |
260 | if (wstart == 0) break; | |
261 | wstart--; | |
262 | continue; | |
263 | } | |
264 | /* We now have wstart on a 'set' bit, we now need to work out | |
265 | * how bit a window to do. To do this we need to scan | |
266 | * forward until the last set bit before the end of the | |
267 | * window */ | |
268 | j=wstart; | |
269 | wvalue=1; | |
270 | wend=0; | |
271 | for (i=1; i<window; i++) | |
272 | { | |
273 | if (wstart-i < 0) break; | |
274 | if (BN_is_bit_set(p,wstart-i)) | |
275 | { | |
276 | wvalue<<=(i-wend); | |
277 | wvalue|=1; | |
278 | wend=i; | |
279 | } | |
280 | } | |
281 | ||
282 | /* wend is the size of the current window */ | |
283 | j=wend+1; | |
284 | /* add the 'bytes above' */ | |
285 | if (!start) | |
286 | for (i=0; i<j; i++) | |
287 | { | |
dfeab068 | 288 | if (!BN_mod_mul_reciprocal(r,r,r,&recp,ctx)) |
d02b48c6 RE |
289 | goto err; |
290 | } | |
291 | ||
292 | /* wvalue will be an odd number < 2^window */ | |
dfeab068 | 293 | if (!BN_mod_mul_reciprocal(r,r,&(val[wvalue>>1]),&recp,ctx)) |
d02b48c6 RE |
294 | goto err; |
295 | ||
296 | /* move the 'window' down further */ | |
297 | wstart-=wend+1; | |
298 | wvalue=0; | |
299 | start=0; | |
300 | if (wstart < 0) break; | |
301 | } | |
302 | ret=1; | |
303 | err: | |
dfeab068 RE |
304 | ctx->tos--; |
305 | for (i=0; i<ts; i++) | |
306 | BN_clear_free(&(val[i])); | |
307 | BN_RECP_CTX_free(&recp); | |
d02b48c6 RE |
308 | return(ret); |
309 | } | |
310 | /* #endif */ | |
311 | ||
312 | /* #ifdef MONT_MUL_MOD */ | |
dfeab068 RE |
313 | int BN_mod_exp_mont(rr,a,p,m,ctx,in_mont) |
314 | BIGNUM *rr; | |
d02b48c6 RE |
315 | BIGNUM *a; |
316 | BIGNUM *p; | |
317 | BIGNUM *m; | |
318 | BN_CTX *ctx; | |
58964a49 | 319 | BN_MONT_CTX *in_mont; |
d02b48c6 RE |
320 | { |
321 | int i,j,bits,ret=0,wstart,wend,window,wvalue; | |
dfeab068 RE |
322 | int start=1,ts=0; |
323 | BIGNUM *d,*aa,*r; | |
324 | BIGNUM val[TABLE_SIZE]; | |
d02b48c6 RE |
325 | BN_MONT_CTX *mont=NULL; |
326 | ||
dfeab068 RE |
327 | bn_check_top(a); |
328 | bn_check_top(p); | |
329 | bn_check_top(m); | |
330 | ||
d02b48c6 RE |
331 | if (!(m->d[0] & 1)) |
332 | { | |
333 | BNerr(BN_F_BN_MOD_EXP_MONT,BN_R_CALLED_WITH_EVEN_MODULUS); | |
334 | return(0); | |
335 | } | |
dfeab068 RE |
336 | d= &(ctx->bn[ctx->tos++]); |
337 | r= &(ctx->bn[ctx->tos++]); | |
d02b48c6 RE |
338 | bits=BN_num_bits(p); |
339 | if (bits == 0) | |
340 | { | |
341 | BN_one(r); | |
342 | return(1); | |
343 | } | |
344 | ||
345 | /* If this is not done, things will break in the montgomery | |
346 | * part */ | |
347 | ||
58964a49 RE |
348 | #if 1 |
349 | if (in_mont != NULL) | |
350 | mont=in_mont; | |
351 | else | |
352 | #endif | |
353 | { | |
354 | if ((mont=BN_MONT_CTX_new()) == NULL) goto err; | |
355 | if (!BN_MONT_CTX_set(mont,m,ctx)) goto err; | |
356 | } | |
d02b48c6 | 357 | |
dfeab068 RE |
358 | BN_init(&val[0]); |
359 | ts=1; | |
d02b48c6 RE |
360 | if (BN_ucmp(a,m) >= 0) |
361 | { | |
dfeab068 RE |
362 | BN_mod(&(val[0]),a,m,ctx); |
363 | aa= &(val[0]); | |
d02b48c6 RE |
364 | } |
365 | else | |
366 | aa=a; | |
dfeab068 RE |
367 | if (!BN_to_montgomery(&(val[0]),aa,mont,ctx)) goto err; /* 1 */ |
368 | if (!BN_mod_mul_montgomery(d,&(val[0]),&(val[0]),mont,ctx)) goto err; /* 2 */ | |
d02b48c6 | 369 | |
58964a49 | 370 | if (bits <= 20) /* This is probably 3 or 0x10001, so just do singles */ |
d02b48c6 | 371 | window=1; |
dfeab068 | 372 | else if (bits >= 256) |
d02b48c6 | 373 | window=5; /* max size of window */ |
dfeab068 | 374 | else if (bits >= 128) |
d02b48c6 RE |
375 | window=4; |
376 | else | |
377 | window=3; | |
378 | ||
379 | j=1<<(window-1); | |
380 | for (i=1; i<j; i++) | |
381 | { | |
dfeab068 RE |
382 | BN_init(&(val[i])); |
383 | if (!BN_mod_mul_montgomery(&(val[i]),&(val[i-1]),d,mont,ctx)) | |
d02b48c6 RE |
384 | goto err; |
385 | } | |
dfeab068 | 386 | ts=i; |
d02b48c6 RE |
387 | |
388 | start=1; /* This is used to avoid multiplication etc | |
389 | * when there is only the value '1' in the | |
390 | * buffer. */ | |
391 | wvalue=0; /* The 'value' of the window */ | |
392 | wstart=bits-1; /* The top bit of the window */ | |
393 | wend=0; /* The bottom bit of the window */ | |
394 | ||
395 | if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err; | |
396 | for (;;) | |
397 | { | |
398 | if (BN_is_bit_set(p,wstart) == 0) | |
399 | { | |
400 | if (!start) | |
58964a49 | 401 | { |
d02b48c6 RE |
402 | if (!BN_mod_mul_montgomery(r,r,r,mont,ctx)) |
403 | goto err; | |
58964a49 | 404 | } |
d02b48c6 RE |
405 | if (wstart == 0) break; |
406 | wstart--; | |
407 | continue; | |
408 | } | |
409 | /* We now have wstart on a 'set' bit, we now need to work out | |
410 | * how bit a window to do. To do this we need to scan | |
411 | * forward until the last set bit before the end of the | |
412 | * window */ | |
413 | j=wstart; | |
414 | wvalue=1; | |
415 | wend=0; | |
416 | for (i=1; i<window; i++) | |
417 | { | |
418 | if (wstart-i < 0) break; | |
419 | if (BN_is_bit_set(p,wstart-i)) | |
420 | { | |
421 | wvalue<<=(i-wend); | |
422 | wvalue|=1; | |
423 | wend=i; | |
424 | } | |
425 | } | |
426 | ||
427 | /* wend is the size of the current window */ | |
428 | j=wend+1; | |
429 | /* add the 'bytes above' */ | |
430 | if (!start) | |
431 | for (i=0; i<j; i++) | |
432 | { | |
433 | if (!BN_mod_mul_montgomery(r,r,r,mont,ctx)) | |
434 | goto err; | |
435 | } | |
436 | ||
437 | /* wvalue will be an odd number < 2^window */ | |
dfeab068 | 438 | if (!BN_mod_mul_montgomery(r,r,&(val[wvalue>>1]),mont,ctx)) |
d02b48c6 RE |
439 | goto err; |
440 | ||
441 | /* move the 'window' down further */ | |
442 | wstart-=wend+1; | |
443 | wvalue=0; | |
444 | start=0; | |
445 | if (wstart < 0) break; | |
446 | } | |
dfeab068 | 447 | BN_from_montgomery(rr,r,mont,ctx); |
d02b48c6 RE |
448 | ret=1; |
449 | err: | |
58964a49 | 450 | if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont); |
dfeab068 RE |
451 | ctx->tos-=2; |
452 | for (i=0; i<ts; i++) | |
453 | BN_clear_free(&(val[i])); | |
d02b48c6 RE |
454 | return(ret); |
455 | } | |
456 | /* #endif */ | |
457 | ||
458 | /* The old fallback, simple version :-) */ | |
459 | int BN_mod_exp_simple(r,a,p,m,ctx) | |
460 | BIGNUM *r; | |
461 | BIGNUM *a; | |
462 | BIGNUM *p; | |
463 | BIGNUM *m; | |
464 | BN_CTX *ctx; | |
465 | { | |
dfeab068 | 466 | int i,j,bits,ret=0,wstart,wend,window,wvalue,ts=0; |
d02b48c6 RE |
467 | int start=1; |
468 | BIGNUM *d; | |
dfeab068 | 469 | BIGNUM val[TABLE_SIZE]; |
d02b48c6 | 470 | |
dfeab068 | 471 | d= &(ctx->bn[ctx->tos++]); |
d02b48c6 RE |
472 | bits=BN_num_bits(p); |
473 | ||
474 | if (bits == 0) | |
475 | { | |
476 | BN_one(r); | |
477 | return(1); | |
478 | } | |
479 | ||
dfeab068 RE |
480 | BN_init(&(val[0])); |
481 | ts=1; | |
482 | if (!BN_mod(&(val[0]),a,m,ctx)) goto err; /* 1 */ | |
483 | if (!BN_mod_mul(d,&(val[0]),&(val[0]),m,ctx)) | |
d02b48c6 RE |
484 | goto err; /* 2 */ |
485 | ||
486 | if (bits <= 17) /* This is probably 3 or 0x10001, so just do singles */ | |
487 | window=1; | |
488 | else if (bits >= 256) | |
489 | window=5; /* max size of window */ | |
490 | else if (bits >= 128) | |
491 | window=4; | |
492 | else | |
493 | window=3; | |
494 | ||
495 | j=1<<(window-1); | |
496 | for (i=1; i<j; i++) | |
497 | { | |
dfeab068 RE |
498 | BN_init(&(val[i])); |
499 | if (!BN_mod_mul(&(val[i]),&(val[i-1]),d,m,ctx)) | |
d02b48c6 RE |
500 | goto err; |
501 | } | |
dfeab068 | 502 | ts=i; |
d02b48c6 RE |
503 | |
504 | start=1; /* This is used to avoid multiplication etc | |
505 | * when there is only the value '1' in the | |
506 | * buffer. */ | |
507 | wvalue=0; /* The 'value' of the window */ | |
508 | wstart=bits-1; /* The top bit of the window */ | |
509 | wend=0; /* The bottom bit of the window */ | |
510 | ||
511 | if (!BN_one(r)) goto err; | |
512 | ||
513 | for (;;) | |
514 | { | |
515 | if (BN_is_bit_set(p,wstart) == 0) | |
516 | { | |
517 | if (!start) | |
518 | if (!BN_mod_mul(r,r,r,m,ctx)) | |
519 | goto err; | |
520 | if (wstart == 0) break; | |
521 | wstart--; | |
522 | continue; | |
523 | } | |
524 | /* We now have wstart on a 'set' bit, we now need to work out | |
525 | * how bit a window to do. To do this we need to scan | |
526 | * forward until the last set bit before the end of the | |
527 | * window */ | |
528 | j=wstart; | |
529 | wvalue=1; | |
530 | wend=0; | |
531 | for (i=1; i<window; i++) | |
532 | { | |
533 | if (wstart-i < 0) break; | |
534 | if (BN_is_bit_set(p,wstart-i)) | |
535 | { | |
536 | wvalue<<=(i-wend); | |
537 | wvalue|=1; | |
538 | wend=i; | |
539 | } | |
540 | } | |
541 | ||
542 | /* wend is the size of the current window */ | |
543 | j=wend+1; | |
544 | /* add the 'bytes above' */ | |
545 | if (!start) | |
546 | for (i=0; i<j; i++) | |
547 | { | |
548 | if (!BN_mod_mul(r,r,r,m,ctx)) | |
549 | goto err; | |
550 | } | |
551 | ||
552 | /* wvalue will be an odd number < 2^window */ | |
dfeab068 | 553 | if (!BN_mod_mul(r,r,&(val[wvalue>>1]),m,ctx)) |
d02b48c6 RE |
554 | goto err; |
555 | ||
556 | /* move the 'window' down further */ | |
557 | wstart-=wend+1; | |
558 | wvalue=0; | |
559 | start=0; | |
560 | if (wstart < 0) break; | |
561 | } | |
562 | ret=1; | |
563 | err: | |
564 | ctx->tos--; | |
dfeab068 RE |
565 | for (i=0; i<ts; i++) |
566 | BN_clear_free(&(val[i])); | |
d02b48c6 RE |
567 | return(ret); |
568 | } | |
569 |