1 /* crypto/bn/bn_mont.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) 1998-2006 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 * Details about Montgomery multiplication algorithms can be found at
114 * http://security.ece.orst.edu/publications.html, e.g.
115 * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and
116 * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
117 */
118
119 #include <stdio.h>
120 #include "cryptlib.h"
121 #include "bn_lcl.h"
122
123 #define MONT_WORD /* use the faster word-based algorithm */
124
125 #if defined(MONT_WORD) && defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)
126 /* This condition means we have a specific non-default build:
127 * In the 0.9.8 branch, OPENSSL_BN_ASM_MONT is normally not set for any
128 * BN_BITS2<=32 platform; an explicit "enable-montasm" is required.
129 * I.e., if we are here, the user intentionally deviates from the
130 * normal stable build to get better Montgomery performance from
131 * the 0.9.9-dev backport.
132 *
133 * In this case only, we also enable BN_from_montgomery_word()
134 * (another non-stable feature from 0.9.9-dev).
135 */
136 #define MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
137 #endif
138
139 #ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
140 static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont);
141 #endif
142
143
144
BN_mod_mul_montgomery(BIGNUM * r,const BIGNUM * a,const BIGNUM * b,BN_MONT_CTX * mont,BN_CTX * ctx)145 int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
146 BN_MONT_CTX *mont, BN_CTX *ctx)
147 {
148 BIGNUM *tmp;
149 int ret=0;
150 #if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD)
151 int num = mont->N.top;
152
153 if (num>1 && a->top==num && b->top==num)
154 {
155 if (bn_wexpand(r,num) == NULL) return(0);
156 #if 0 /* for OpenSSL 0.9.9 mont->n0 */
157 if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,mont->n0,num))
158 #else
159 if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,&mont->n0,num))
160 #endif
161 {
162 r->neg = a->neg^b->neg;
163 r->top = num;
164 bn_correct_top(r);
165 return(1);
166 }
167 }
168 #endif
169
170 BN_CTX_start(ctx);
171 tmp = BN_CTX_get(ctx);
172 if (tmp == NULL) goto err;
173
174 bn_check_top(tmp);
175 if (a == b)
176 {
177 if (!BN_sqr(tmp,a,ctx)) goto err;
178 }
179 else
180 {
181 if (!BN_mul(tmp,a,b,ctx)) goto err;
182 }
183 /* reduce from aRR to aR */
184 #ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
185 if (!BN_from_montgomery_word(r,tmp,mont)) goto err;
186 #else
187 if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
188 #endif
189 bn_check_top(r);
190 ret=1;
191 err:
192 BN_CTX_end(ctx);
193 return(ret);
194 }
195
196 #ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
BN_from_montgomery_word(BIGNUM * ret,BIGNUM * r,BN_MONT_CTX * mont)197 static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
198 {
199 BIGNUM *n;
200 BN_ULONG *ap,*np,*rp,n0,v,*nrp;
201 int al,nl,max,i,x,ri;
202
203 n= &(mont->N);
204 /* mont->ri is the size of mont->N in bits (rounded up
205 to the word size) */
206 al=ri=mont->ri/BN_BITS2;
207
208 nl=n->top;
209 if ((al == 0) || (nl == 0)) { ret->top=0; return(1); }
210
211 max=(nl+al+1); /* allow for overflow (no?) XXX */
212 if (bn_wexpand(r,max) == NULL) return(0);
213
214 r->neg^=n->neg;
215 np=n->d;
216 rp=r->d;
217 nrp= &(r->d[nl]);
218
219 /* clear the top words of T */
220 for (i=r->top; i<max; i++) /* memset? XXX */
221 r->d[i]=0;
222
223 r->top=max;
224 #if 0 /* for OpenSSL 0.9.9 mont->n0 */
225 n0=mont->n0[0];
226 #else
227 n0=mont->n0;
228 #endif
229
230 #ifdef BN_COUNT
231 fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl);
232 #endif
233 for (i=0; i<nl; i++)
234 {
235 #ifdef __TANDEM
236 {
237 long long t1;
238 long long t2;
239 long long t3;
240 t1 = rp[0] * (n0 & 0177777);
241 t2 = 037777600000l;
242 t2 = n0 & t2;
243 t3 = rp[0] & 0177777;
244 t2 = (t3 * t2) & BN_MASK2;
245 t1 = t1 + t2;
246 v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
247 }
248 #else
249 v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
250 #endif
251 nrp++;
252 rp++;
253 if (((nrp[-1]+=v)&BN_MASK2) >= v)
254 continue;
255 else
256 {
257 if (((++nrp[0])&BN_MASK2) != 0) continue;
258 if (((++nrp[1])&BN_MASK2) != 0) continue;
259 for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
260 }
261 }
262 bn_correct_top(r);
263
264 /* mont->ri will be a multiple of the word size and below code
265 * is kind of BN_rshift(ret,r,mont->ri) equivalent */
266 if (r->top <= ri)
267 {
268 ret->top=0;
269 return(1);
270 }
271 al=r->top-ri;
272
273 if (bn_wexpand(ret,ri) == NULL) return(0);
274 x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
275 ret->top=x=(ri&~x)|(al&x); /* min(ri,al) */
276 ret->neg=r->neg;
277
278 rp=ret->d;
279 ap=&(r->d[ri]);
280
281 {
282 size_t m1,m2;
283
284 v=bn_sub_words(rp,ap,np,ri);
285 /* this ----------------^^ works even in al<ri case
286 * thanks to zealous zeroing of top of the vector in the
287 * beginning. */
288
289 /* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
290 /* in other words if subtraction result is real, then
291 * trick unconditional memcpy below to perform in-place
292 * "refresh" instead of actual copy. */
293 m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1); /* al<ri */
294 m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1); /* al>ri */
295 m1|=m2; /* (al!=ri) */
296 m1|=(0-(size_t)v); /* (al!=ri || v) */
297 m1&=~m2; /* (al!=ri || v) && !al>ri */
298 nrp=(BN_ULONG *)(((size_t)rp&~m1)|((size_t)ap&m1));
299 }
300
301 /* 'i<ri' is chosen to eliminate dependency on input data, even
302 * though it results in redundant copy in al<ri case. */
303 for (i=0,ri-=4; i<ri; i+=4)
304 {
305 BN_ULONG t1,t2,t3,t4;
306
307 t1=nrp[i+0];
308 t2=nrp[i+1];
309 t3=nrp[i+2]; ap[i+0]=0;
310 t4=nrp[i+3]; ap[i+1]=0;
311 rp[i+0]=t1; ap[i+2]=0;
312 rp[i+1]=t2; ap[i+3]=0;
313 rp[i+2]=t3;
314 rp[i+3]=t4;
315 }
316 for (ri+=4; i<ri; i++)
317 rp[i]=nrp[i], ap[i]=0;
318 bn_correct_top(r);
319 bn_correct_top(ret);
320 bn_check_top(ret);
321
322 return(1);
323 }
324
BN_from_montgomery(BIGNUM * ret,const BIGNUM * a,BN_MONT_CTX * mont,BN_CTX * ctx)325 int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
326 BN_CTX *ctx)
327 {
328 int retn=0;
329 BIGNUM *t;
330
331 BN_CTX_start(ctx);
332 if ((t = BN_CTX_get(ctx)) && BN_copy(t,a))
333 retn = BN_from_montgomery_word(ret,t,mont);
334 BN_CTX_end(ctx);
335 return retn;
336 }
337
338 #else /* !MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD */
339
BN_from_montgomery(BIGNUM * ret,const BIGNUM * a,BN_MONT_CTX * mont,BN_CTX * ctx)340 int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
341 BN_CTX *ctx)
342 {
343 int retn=0;
344
345 #ifdef MONT_WORD
346 BIGNUM *n,*r;
347 BN_ULONG *ap,*np,*rp,n0,v,*nrp;
348 int al,nl,max,i,x,ri;
349
350 BN_CTX_start(ctx);
351 if ((r = BN_CTX_get(ctx)) == NULL) goto err;
352
353 if (!BN_copy(r,a)) goto err;
354 n= &(mont->N);
355
356 ap=a->d;
357 /* mont->ri is the size of mont->N in bits (rounded up
358 to the word size) */
359 al=ri=mont->ri/BN_BITS2;
360
361 nl=n->top;
362 if ((al == 0) || (nl == 0)) { r->top=0; return(1); }
363
364 max=(nl+al+1); /* allow for overflow (no?) XXX */
365 if (bn_wexpand(r,max) == NULL) goto err;
366
367 r->neg=a->neg^n->neg;
368 np=n->d;
369 rp=r->d;
370 nrp= &(r->d[nl]);
371
372 /* clear the top words of T */
373 #if 1
374 for (i=r->top; i<max; i++) /* memset? XXX */
375 r->d[i]=0;
376 #else
377 memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG));
378 #endif
379
380 r->top=max;
381 n0=mont->n0;
382
383 #ifdef BN_COUNT
384 fprintf(stderr,"word BN_from_montgomery %d * %d\n",nl,nl);
385 #endif
386 for (i=0; i<nl; i++)
387 {
388 #ifdef __TANDEM
389 {
390 long long t1;
391 long long t2;
392 long long t3;
393 t1 = rp[0] * (n0 & 0177777);
394 t2 = 037777600000l;
395 t2 = n0 & t2;
396 t3 = rp[0] & 0177777;
397 t2 = (t3 * t2) & BN_MASK2;
398 t1 = t1 + t2;
399 v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
400 }
401 #else
402 v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
403 #endif
404 nrp++;
405 rp++;
406 if (((nrp[-1]+=v)&BN_MASK2) >= v)
407 continue;
408 else
409 {
410 if (((++nrp[0])&BN_MASK2) != 0) continue;
411 if (((++nrp[1])&BN_MASK2) != 0) continue;
412 for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
413 }
414 }
415 bn_correct_top(r);
416
417 /* mont->ri will be a multiple of the word size and below code
418 * is kind of BN_rshift(ret,r,mont->ri) equivalent */
419 if (r->top <= ri)
420 {
421 ret->top=0;
422 retn=1;
423 goto err;
424 }
425 al=r->top-ri;
426
427 # define BRANCH_FREE 1
428 # if BRANCH_FREE
429 if (bn_wexpand(ret,ri) == NULL) goto err;
430 x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
431 ret->top=x=(ri&~x)|(al&x); /* min(ri,al) */
432 ret->neg=r->neg;
433
434 rp=ret->d;
435 ap=&(r->d[ri]);
436
437 {
438 size_t m1,m2;
439
440 v=bn_sub_words(rp,ap,np,ri);
441 /* this ----------------^^ works even in al<ri case
442 * thanks to zealous zeroing of top of the vector in the
443 * beginning. */
444
445 /* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
446 /* in other words if subtraction result is real, then
447 * trick unconditional memcpy below to perform in-place
448 * "refresh" instead of actual copy. */
449 m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1); /* al<ri */
450 m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1); /* al>ri */
451 m1|=m2; /* (al!=ri) */
452 m1|=(0-(size_t)v); /* (al!=ri || v) */
453 m1&=~m2; /* (al!=ri || v) && !al>ri */
454 nrp=(BN_ULONG *)(((size_t)rp&~m1)|((size_t)ap&m1));
455 }
456
457 /* 'i<ri' is chosen to eliminate dependency on input data, even
458 * though it results in redundant copy in al<ri case. */
459 for (i=0,ri-=4; i<ri; i+=4)
460 {
461 BN_ULONG t1,t2,t3,t4;
462
463 t1=nrp[i+0];
464 t2=nrp[i+1];
465 t3=nrp[i+2]; ap[i+0]=0;
466 t4=nrp[i+3]; ap[i+1]=0;
467 rp[i+0]=t1; ap[i+2]=0;
468 rp[i+1]=t2; ap[i+3]=0;
469 rp[i+2]=t3;
470 rp[i+3]=t4;
471 }
472 for (ri+=4; i<ri; i++)
473 rp[i]=nrp[i], ap[i]=0;
474 bn_correct_top(r);
475 bn_correct_top(ret);
476 # else
477 if (bn_wexpand(ret,al) == NULL) goto err;
478 ret->top=al;
479 ret->neg=r->neg;
480
481 rp=ret->d;
482 ap=&(r->d[ri]);
483 al-=4;
484 for (i=0; i<al; i+=4)
485 {
486 BN_ULONG t1,t2,t3,t4;
487
488 t1=ap[i+0];
489 t2=ap[i+1];
490 t3=ap[i+2];
491 t4=ap[i+3];
492 rp[i+0]=t1;
493 rp[i+1]=t2;
494 rp[i+2]=t3;
495 rp[i+3]=t4;
496 }
497 al+=4;
498 for (; i<al; i++)
499 rp[i]=ap[i];
500 # endif
501 #else /* !MONT_WORD */
502 BIGNUM *t1,*t2;
503
504 BN_CTX_start(ctx);
505 t1 = BN_CTX_get(ctx);
506 t2 = BN_CTX_get(ctx);
507 if (t1 == NULL || t2 == NULL) goto err;
508
509 if (!BN_copy(t1,a)) goto err;
510 BN_mask_bits(t1,mont->ri);
511
512 if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err;
513 BN_mask_bits(t2,mont->ri);
514
515 if (!BN_mul(t1,t2,&mont->N,ctx)) goto err;
516 if (!BN_add(t2,a,t1)) goto err;
517 if (!BN_rshift(ret,t2,mont->ri)) goto err;
518 #endif /* MONT_WORD */
519
520 #if !defined(BRANCH_FREE) || BRANCH_FREE==0
521 if (BN_ucmp(ret, &(mont->N)) >= 0)
522 {
523 if (!BN_usub(ret,ret,&(mont->N))) goto err;
524 }
525 #endif
526 retn=1;
527 bn_check_top(ret);
528 err:
529 BN_CTX_end(ctx);
530 return(retn);
531 }
532 #endif /* MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD */
533
BN_MONT_CTX_new(void)534 BN_MONT_CTX *BN_MONT_CTX_new(void)
535 {
536 BN_MONT_CTX *ret;
537
538 if ((ret=(BN_MONT_CTX *)OPENSSL_malloc(sizeof(BN_MONT_CTX))) == NULL)
539 return(NULL);
540
541 BN_MONT_CTX_init(ret);
542 ret->flags=BN_FLG_MALLOCED;
543 return(ret);
544 }
545
BN_MONT_CTX_init(BN_MONT_CTX * ctx)546 void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
547 {
548 ctx->ri=0;
549 BN_init(&(ctx->RR));
550 BN_init(&(ctx->N));
551 BN_init(&(ctx->Ni));
552 #if 0 /* for OpenSSL 0.9.9 mont->n0 */
553 ctx->n0[0] = ctx->n0[1] = 0;
554 #else
555 ctx->n0 = 0;
556 #endif
557 ctx->flags=0;
558 }
559
BN_MONT_CTX_free(BN_MONT_CTX * mont)560 void BN_MONT_CTX_free(BN_MONT_CTX *mont)
561 {
562 if(mont == NULL)
563 return;
564
565 BN_free(&(mont->RR));
566 BN_free(&(mont->N));
567 BN_free(&(mont->Ni));
568 if (mont->flags & BN_FLG_MALLOCED)
569 OPENSSL_free(mont);
570 }
571
BN_MONT_CTX_set(BN_MONT_CTX * mont,const BIGNUM * mod,BN_CTX * ctx)572 int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
573 {
574 int ret = 0;
575 BIGNUM *Ri,*R;
576
577 BN_CTX_start(ctx);
578 if((Ri = BN_CTX_get(ctx)) == NULL) goto err;
579 R= &(mont->RR); /* grab RR as a temp */
580 if (!BN_copy(&(mont->N),mod)) goto err; /* Set N */
581 mont->N.neg = 0;
582
583 #ifdef MONT_WORD
584 {
585 BIGNUM tmod;
586 BN_ULONG buf[2];
587
588 mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
589 BN_zero(R);
590 #if 0 /* for OpenSSL 0.9.9 mont->n0, would be "#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)",
591 only certain BN_BITS2<=32 platforms actually need this */
592 if (!(BN_set_bit(R,2*BN_BITS2))) goto err; /* R */
593 #else
594 if (!(BN_set_bit(R,BN_BITS2))) goto err; /* R */
595 #endif
596
597 buf[0]=mod->d[0]; /* tmod = N mod word size */
598 buf[1]=0;
599
600 BN_init(&tmod);
601 tmod.d=buf;
602 tmod.top = buf[0] != 0 ? 1 : 0;
603 tmod.dmax=2;
604 tmod.neg=0;
605
606 #if 0 /* for OpenSSL 0.9.9 mont->n0, would be "#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)";
607 only certain BN_BITS2<=32 platforms actually need this */
608 tmod.top=0;
609 if ((buf[0] = mod->d[0])) tmod.top=1;
610 if ((buf[1] = mod->top>1 ? mod->d[1] : 0)) tmod.top=2;
611
612 if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
613 goto err;
614 if (!BN_lshift(Ri,Ri,2*BN_BITS2)) goto err; /* R*Ri */
615 if (!BN_is_zero(Ri))
616 {
617 if (!BN_sub_word(Ri,1)) goto err;
618 }
619 else /* if N mod word size == 1 */
620 {
621 if (bn_expand(Ri,(int)sizeof(BN_ULONG)*2) == NULL)
622 goto err;
623 /* Ri-- (mod double word size) */
624 Ri->neg=0;
625 Ri->d[0]=BN_MASK2;
626 Ri->d[1]=BN_MASK2;
627 Ri->top=2;
628 }
629 if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
630 /* Ni = (R*Ri-1)/N,
631 * keep only couple of least significant words: */
632 mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
633 mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0;
634 #else
635 /* Ri = R^-1 mod N*/
636 if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
637 goto err;
638 if (!BN_lshift(Ri,Ri,BN_BITS2)) goto err; /* R*Ri */
639 if (!BN_is_zero(Ri))
640 {
641 if (!BN_sub_word(Ri,1)) goto err;
642 }
643 else /* if N mod word size == 1 */
644 {
645 if (!BN_set_word(Ri,BN_MASK2)) goto err; /* Ri-- (mod word size) */
646 }
647 if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
648 /* Ni = (R*Ri-1)/N,
649 * keep only least significant word: */
650 # if 0 /* for OpenSSL 0.9.9 mont->n0 */
651 mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
652 mont->n0[1] = 0;
653 # else
654 mont->n0 = (Ri->top > 0) ? Ri->d[0] : 0;
655 # endif
656 #endif
657 }
658 #else /* !MONT_WORD */
659 { /* bignum version */
660 mont->ri=BN_num_bits(&mont->N);
661 BN_zero(R);
662 if (!BN_set_bit(R,mont->ri)) goto err; /* R = 2^ri */
663 /* Ri = R^-1 mod N*/
664 if ((BN_mod_inverse(Ri,R,&mont->N,ctx)) == NULL)
665 goto err;
666 if (!BN_lshift(Ri,Ri,mont->ri)) goto err; /* R*Ri */
667 if (!BN_sub_word(Ri,1)) goto err;
668 /* Ni = (R*Ri-1) / N */
669 if (!BN_div(&(mont->Ni),NULL,Ri,&mont->N,ctx)) goto err;
670 }
671 #endif
672
673 /* setup RR for conversions */
674 BN_zero(&(mont->RR));
675 if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err;
676 if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err;
677
678 ret = 1;
679 err:
680 BN_CTX_end(ctx);
681 return ret;
682 }
683
BN_MONT_CTX_copy(BN_MONT_CTX * to,BN_MONT_CTX * from)684 BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from)
685 {
686 if (to == from) return(to);
687
688 if (!BN_copy(&(to->RR),&(from->RR))) return NULL;
689 if (!BN_copy(&(to->N),&(from->N))) return NULL;
690 if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL;
691 to->ri=from->ri;
692 #if 0 /* for OpenSSL 0.9.9 mont->n0 */
693 to->n0[0]=from->n0[0];
694 to->n0[1]=from->n0[1];
695 #else
696 to->n0=from->n0;
697 #endif
698 return(to);
699 }
700
BN_MONT_CTX_set_locked(BN_MONT_CTX ** pmont,int lock,const BIGNUM * mod,BN_CTX * ctx)701 BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, int lock,
702 const BIGNUM *mod, BN_CTX *ctx)
703 {
704 int got_write_lock = 0;
705 BN_MONT_CTX *ret;
706
707 CRYPTO_r_lock(lock);
708 if (!*pmont)
709 {
710 CRYPTO_r_unlock(lock);
711 CRYPTO_w_lock(lock);
712 got_write_lock = 1;
713
714 if (!*pmont)
715 {
716 ret = BN_MONT_CTX_new();
717 if (ret && !BN_MONT_CTX_set(ret, mod, ctx))
718 BN_MONT_CTX_free(ret);
719 else
720 *pmont = ret;
721 }
722 }
723
724 ret = *pmont;
725
726 if (got_write_lock)
727 CRYPTO_w_unlock(lock);
728 else
729 CRYPTO_r_unlock(lock);
730
731 return ret;
732 }
733