1 /* crypto/engine/eng_rsax.c */
2 /* Copyright (c) 2010-2010 Intel Corp.
3 * Author: Vinodh.Gopal@intel.com
4 * Jim Guilford
5 * Erdinc.Ozturk@intel.com
6 * Maxim.Perminov@intel.com
7 * Ying.Huang@intel.com
8 *
9 * More information about algorithm used can be found at:
10 * http://www.cse.buffalo.edu/srds2009/escs2009_submission_Gopal.pdf
11 */
12 /* ====================================================================
13 * Copyright (c) 1999-2001 The OpenSSL Project. All rights reserved.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 *
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 *
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in
24 * the documentation and/or other materials provided with the
25 * distribution.
26 *
27 * 3. All advertising materials mentioning features or use of this
28 * software must display the following acknowledgment:
29 * "This product includes software developed by the OpenSSL Project
30 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
31 *
32 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
33 * endorse or promote products derived from this software without
34 * prior written permission. For written permission, please contact
35 * licensing@OpenSSL.org.
36 *
37 * 5. Products derived from this software may not be called "OpenSSL"
38 * nor may "OpenSSL" appear in their names without prior written
39 * permission of the OpenSSL Project.
40 *
41 * 6. Redistributions of any form whatsoever must retain the following
42 * acknowledgment:
43 * "This product includes software developed by the OpenSSL Project
44 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
45 *
46 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
47 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
48 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
49 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
50 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
51 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
52 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
53 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
54 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
55 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
56 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
57 * OF THE POSSIBILITY OF SUCH DAMAGE.
58 * ====================================================================
59 *
60 * This product includes cryptographic software written by Eric Young
61 * (eay@cryptsoft.com). This product includes software written by Tim
62 * Hudson (tjh@cryptsoft.com).
63 */
64
65 #include <openssl/opensslconf.h>
66
67 #include <stdio.h>
68 #include <string.h>
69 #include <openssl/crypto.h>
70 #include <openssl/buffer.h>
71 #include <openssl/engine.h>
72 #ifndef OPENSSL_NO_RSA
73 #include <openssl/rsa.h>
74 #endif
75 #include <openssl/bn.h>
76 #include <openssl/err.h>
77
78 /* RSAX is available **ONLY* on x86_64 CPUs */
79 #undef COMPILE_RSAX
80
81 #if (defined(__x86_64) || defined(__x86_64__) || \
82 defined(_M_AMD64) || defined (_M_X64)) && !defined(OPENSSL_NO_ASM)
83 #define COMPILE_RSAX
84 static ENGINE *ENGINE_rsax (void);
85 #endif
86
87 void ENGINE_load_rsax (void)
88 {
89 /* On non-x86 CPUs it just returns. */
90 #ifdef COMPILE_RSAX
91 ENGINE *toadd = ENGINE_rsax();
92 if(!toadd) return;
93 ENGINE_add(toadd);
94 ENGINE_free(toadd);
95 ERR_clear_error();
96 #endif
97 }
98
99 #ifdef COMPILE_RSAX
100 #define E_RSAX_LIB_NAME "rsax engine"
101
102 static int e_rsax_destroy(ENGINE *e);
103 static int e_rsax_init(ENGINE *e);
104 static int e_rsax_finish(ENGINE *e);
105 static int e_rsax_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void));
106
107 #ifndef OPENSSL_NO_RSA
108 /* RSA stuff */
109 static int e_rsax_rsa_mod_exp(BIGNUM *r, const BIGNUM *I, RSA *rsa, BN_CTX *ctx);
110 static int e_rsax_rsa_finish(RSA *r);
111 #endif
112
113 static const ENGINE_CMD_DEFN e_rsax_cmd_defns[] = {
114 {0, NULL, NULL, 0}
115 };
116
117 #ifndef OPENSSL_NO_RSA
118 /* Our internal RSA_METHOD that we provide pointers to */
119 static RSA_METHOD e_rsax_rsa =
120 {
121 "Intel RSA-X method",
122 NULL,
123 NULL,
124 NULL,
125 NULL,
126 e_rsax_rsa_mod_exp,
127 NULL,
128 NULL,
129 e_rsax_rsa_finish,
130 RSA_FLAG_CACHE_PUBLIC|RSA_FLAG_CACHE_PRIVATE,
131 NULL,
132 NULL,
133 NULL
134 };
135 #endif
136
137 /* Constants used when creating the ENGINE */
138 static const char *engine_e_rsax_id = "rsax";
139 static const char *engine_e_rsax_name = "RSAX engine support";
140
141 /* This internal function is used by ENGINE_rsax() */
142 static int bind_helper(ENGINE *e)
143 {
144 #ifndef OPENSSL_NO_RSA
145 const RSA_METHOD *meth1;
146 #endif
147 if(!ENGINE_set_id(e, engine_e_rsax_id) ||
148 !ENGINE_set_name(e, engine_e_rsax_name) ||
149 #ifndef OPENSSL_NO_RSA
150 !ENGINE_set_RSA(e, &e_rsax_rsa) ||
151 #endif
152 !ENGINE_set_destroy_function(e, e_rsax_destroy) ||
153 !ENGINE_set_init_function(e, e_rsax_init) ||
154 !ENGINE_set_finish_function(e, e_rsax_finish) ||
155 !ENGINE_set_ctrl_function(e, e_rsax_ctrl) ||
156 !ENGINE_set_cmd_defns(e, e_rsax_cmd_defns))
157 return 0;
158
159 #ifndef OPENSSL_NO_RSA
160 meth1 = RSA_PKCS1_SSLeay();
161 e_rsax_rsa.rsa_pub_enc = meth1->rsa_pub_enc;
162 e_rsax_rsa.rsa_pub_dec = meth1->rsa_pub_dec;
163 e_rsax_rsa.rsa_priv_enc = meth1->rsa_priv_enc;
164 e_rsax_rsa.rsa_priv_dec = meth1->rsa_priv_dec;
165 e_rsax_rsa.bn_mod_exp = meth1->bn_mod_exp;
166 #endif
167 return 1;
168 }
169
170 static ENGINE *ENGINE_rsax(void)
171 {
172 ENGINE *ret = ENGINE_new();
173 if(!ret)
174 return NULL;
175 if(!bind_helper(ret))
176 {
177 ENGINE_free(ret);
178 return NULL;
179 }
180 return ret;
181 }
182
183 #ifndef OPENSSL_NO_RSA
184 /* Used to attach our own key-data to an RSA structure */
185 static int rsax_ex_data_idx = -1;
186 #endif
187
188 static int e_rsax_destroy(ENGINE *e)
189 {
190 return 1;
191 }
192
193 /* (de)initialisation functions. */
194 static int e_rsax_init(ENGINE *e)
195 {
196 #ifndef OPENSSL_NO_RSA
197 if (rsax_ex_data_idx == -1)
198 rsax_ex_data_idx = RSA_get_ex_new_index(0,
199 NULL,
200 NULL, NULL, NULL);
201 #endif
202 if (rsax_ex_data_idx == -1)
203 return 0;
204 return 1;
205 }
206
207 static int e_rsax_finish(ENGINE *e)
208 {
209 return 1;
210 }
211
212 static int e_rsax_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void))
213 {
214 int to_return = 1;
215
216 switch(cmd)
217 {
218 /* The command isn't understood by this engine */
219 default:
220 to_return = 0;
221 break;
222 }
223
224 return to_return;
225 }
226
227
228 #ifndef OPENSSL_NO_RSA
229
230 #ifdef _WIN32
231 typedef unsigned __int64 UINT64;
232 #else
233 typedef unsigned long long UINT64;
234 #endif
235 typedef unsigned short UINT16;
236
237 /* Table t is interleaved in the following manner:
238 * The order in memory is t[0][0], t[0][1], ..., t[0][7], t[1][0], ...
239 * A particular 512-bit value is stored in t[][index] rather than the more
240 * normal t[index][]; i.e. the qwords of a particular entry in t are not
241 * adjacent in memory
242 */
243
244 /* Init BIGNUM b from the interleaved UINT64 array */
245 static int interleaved_array_to_bn_512(BIGNUM* b, UINT64 *array);
246
247 /* Extract array elements from BIGNUM b
248 * To set the whole array from b, call with n=8
249 */
250 static int bn_extract_to_array_512(const BIGNUM* b, unsigned int n, UINT64 *array);
251
252 struct mod_ctx_512 {
253 UINT64 t[8][8];
254 UINT64 m[8];
255 UINT64 m1[8]; /* 2^278 % m */
256 UINT64 m2[8]; /* 2^640 % m */
257 UINT64 k1[2]; /* (- 1/m) % 2^128 */
258 };
259
260 static int mod_exp_pre_compute_data_512(UINT64 *m, struct mod_ctx_512 *data);
261
262 void mod_exp_512(UINT64 *result, /* 512 bits, 8 qwords */
263 UINT64 *g, /* 512 bits, 8 qwords */
264 UINT64 *exp, /* 512 bits, 8 qwords */
265 struct mod_ctx_512 *data);
266
267 typedef struct st_e_rsax_mod_ctx
268 {
269 UINT64 type;
270 union {
271 struct mod_ctx_512 b512;
272 } ctx;
273
274 } E_RSAX_MOD_CTX;
275
276 static E_RSAX_MOD_CTX *e_rsax_get_ctx(RSA *rsa, int idx, BIGNUM* m)
277 {
278 E_RSAX_MOD_CTX *hptr;
279
280 if (idx < 0 || idx > 2)
281 return NULL;
282
283 hptr = RSA_get_ex_data(rsa, rsax_ex_data_idx);
284 if (!hptr) {
285 hptr = OPENSSL_malloc(3*sizeof(E_RSAX_MOD_CTX));
286 if (!hptr) return NULL;
287 hptr[2].type = hptr[1].type= hptr[0].type = 0;
288 RSA_set_ex_data(rsa, rsax_ex_data_idx, hptr);
289 }
290
291 if (hptr[idx].type == (UINT64)BN_num_bits(m))
292 return hptr+idx;
293
294 if (BN_num_bits(m) == 512) {
295 UINT64 _m[8];
296 bn_extract_to_array_512(m, 8, _m);
297 memset( &hptr[idx].ctx.b512, 0, sizeof(struct mod_ctx_512));
298 mod_exp_pre_compute_data_512(_m, &hptr[idx].ctx.b512);
299 }
300
301 hptr[idx].type = BN_num_bits(m);
302 return hptr+idx;
303 }
304
305 static int e_rsax_rsa_finish(RSA *rsa)
306 {
307 E_RSAX_MOD_CTX *hptr = RSA_get_ex_data(rsa, rsax_ex_data_idx);
308 if(hptr)
309 {
310 OPENSSL_free(hptr);
311 RSA_set_ex_data(rsa, rsax_ex_data_idx, NULL);
312 }
313 if (rsa->_method_mod_n)
314 BN_MONT_CTX_free(rsa->_method_mod_n);
315 if (rsa->_method_mod_p)
316 BN_MONT_CTX_free(rsa->_method_mod_p);
317 if (rsa->_method_mod_q)
318 BN_MONT_CTX_free(rsa->_method_mod_q);
319 return 1;
320 }
321
322
323 static int e_rsax_bn_mod_exp(BIGNUM *r, const BIGNUM *g, const BIGNUM *e,
324 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont, E_RSAX_MOD_CTX* rsax_mod_ctx )
325 {
326 if (rsax_mod_ctx && BN_get_flags(e, BN_FLG_CONSTTIME) != 0) {
327 if (BN_num_bits(m) == 512) {
328 UINT64 _r[8];
329 UINT64 _g[8];
330 UINT64 _e[8];
331
332 /* Init the arrays from the BIGNUMs */
333 bn_extract_to_array_512(g, 8, _g);
334 bn_extract_to_array_512(e, 8, _e);
335
336 mod_exp_512(_r, _g, _e, &rsax_mod_ctx->ctx.b512);
337 /* Return the result in the BIGNUM */
338 interleaved_array_to_bn_512(r, _r);
339 return 1;
340 }
341 }
342
343 return BN_mod_exp_mont(r, g, e, m, ctx, in_mont);
344 }
345
346 /* Declares for the Intel CIAP 512-bit / CRT / 1024 bit RSA modular
347 * exponentiation routine precalculations and a structure to hold the
348 * necessary values. These files are meant to live in crypto/rsa/ in
349 * the target openssl.
350 */
351
352 /*
353 * Local method: extracts a piece from a BIGNUM, to fit it into
354 * an array. Call with n=8 to extract an entire 512-bit BIGNUM
355 */
356 static int bn_extract_to_array_512(const BIGNUM* b, unsigned int n, UINT64 *array)
357 {
358 int i;
359 UINT64 tmp;
360 unsigned char bn_buff[64];
361 memset(bn_buff, 0, 64);
362 if (BN_num_bytes(b) > 64) {
363 printf ("Can't support this byte size\n");
364 return 0; }
365 if (BN_num_bytes(b)!=0) {
366 if (!BN_bn2bin(b, bn_buff+(64-BN_num_bytes(b)))) {
367 printf ("Error's in bn2bin\n");
368 /* We have to error, here */
369 return 0; } }
370 while (n-- > 0) {
371 array[n] = 0;
372 for (i=7; i>=0; i--) {
373 tmp = bn_buff[63-(n*8+i)];
374 array[n] |= tmp << (8*i); } }
375 return 1;
376 }
377
378 /* Init a 512-bit BIGNUM from the UINT64*_ (8 * 64) interleaved array */
379 static int interleaved_array_to_bn_512(BIGNUM* b, UINT64 *array)
380 {
381 unsigned char tmp[64];
382 int n=8;
383 int i;
384 while (n-- > 0) {
385 for (i = 7; i>=0; i--) {
386 tmp[63-(n*8+i)] = (unsigned char)(array[n]>>(8*i)); } }
387 BN_bin2bn(tmp, 64, b);
388 return 0;
389 }
390
391
392 /* The main 512bit precompute call */
393 static int mod_exp_pre_compute_data_512(UINT64 *m, struct mod_ctx_512 *data)
394 {
395 BIGNUM two_768, two_640, two_128, two_512, tmp, _m, tmp2;
396
397 /* We need a BN_CTX for the modulo functions */
398 BN_CTX* ctx;
399 /* Some tmps */
400 UINT64 _t[8];
401 int i, j, ret = 0;
402
403 /* Init _m with m */
404 BN_init(&_m);
405 interleaved_array_to_bn_512(&_m, m);
406 memset(_t, 0, 64);
407
408 /* Inits */
409 BN_init(&two_768);
410 BN_init(&two_640);
411 BN_init(&two_128);
412 BN_init(&two_512);
413 BN_init(&tmp);
414 BN_init(&tmp2);
415
416 /* Create our context */
417 if ((ctx=BN_CTX_new()) == NULL) { goto err; }
418 BN_CTX_start(ctx);
419
420 /*
421 * For production, if you care, these only need to be set once,
422 * and may be made constants.
423 */
424 BN_lshift(&two_768, BN_value_one(), 768);
425 BN_lshift(&two_640, BN_value_one(), 640);
426 BN_lshift(&two_128, BN_value_one(), 128);
427 BN_lshift(&two_512, BN_value_one(), 512);
428
429 if (0 == (m[7] & 0x8000000000000000)) {
430 exit(1);
431 }
432 if (0 == (m[0] & 0x1)) { /* Odd modulus required for Mont */
433 exit(1);
434 }
435
436 /* Precompute m1 */
437 BN_mod(&tmp, &two_768, &_m, ctx);
438 if (!bn_extract_to_array_512(&tmp, 8, &data->m1[0])) {
439 goto err; }
440
441 /* Precompute m2 */
442 BN_mod(&tmp, &two_640, &_m, ctx);
443 if (!bn_extract_to_array_512(&tmp, 8, &data->m2[0])) {
444 goto err;
445 }
446
447 /*
448 * Precompute k1, a 128b number = ((-1)* m-1 ) mod 2128; k1 should
449 * be non-negative.
450 */
451 BN_mod_inverse(&tmp, &_m, &two_128, ctx);
452 if (!BN_is_zero(&tmp)) { BN_sub(&tmp, &two_128, &tmp); }
453 if (!bn_extract_to_array_512(&tmp, 2, &data->k1[0])) {
454 goto err; }
455
456 /* Precompute t */
457 for (i=0; i<8; i++) {
458 BN_zero(&tmp);
459 if (i & 1) { BN_add(&tmp, &two_512, &tmp); }
460 if (i & 2) { BN_add(&tmp, &two_512, &tmp); }
461 if (i & 4) { BN_add(&tmp, &two_640, &tmp); }
462
463 BN_nnmod(&tmp2, &tmp, &_m, ctx);
464 if (!bn_extract_to_array_512(&tmp2, 8, _t)) {
465 goto err; }
466 for (j=0; j<8; j++) data->t[j][i] = _t[j]; }
467
468 /* Precompute m */
469 for (i=0; i<8; i++) {
470 data->m[i] = m[i]; }
471
472 ret = 1;
473
474 err:
475 /* Cleanup */
476 if (ctx != NULL) {
477 BN_CTX_end(ctx); BN_CTX_free(ctx); }
478 BN_free(&two_768);
479 BN_free(&two_640);
480 BN_free(&two_128);
481 BN_free(&two_512);
482 BN_free(&tmp);
483 BN_free(&tmp2);
484 BN_free(&_m);
485
486 return ret;
487 }
488
489
490 static int e_rsax_rsa_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
491 {
492 BIGNUM *r1,*m1,*vrfy;
493 BIGNUM local_dmp1,local_dmq1,local_c,local_r1;
494 BIGNUM *dmp1,*dmq1,*c,*pr1;
495 int ret=0;
496
497 BN_CTX_start(ctx);
498 r1 = BN_CTX_get(ctx);
499 m1 = BN_CTX_get(ctx);
500 vrfy = BN_CTX_get(ctx);
501
502 {
503 BIGNUM local_p, local_q;
504 BIGNUM *p = NULL, *q = NULL;
505 int error = 0;
506
507 /* Make sure BN_mod_inverse in Montgomery
508 * intialization uses the BN_FLG_CONSTTIME flag
509 * (unless RSA_FLAG_NO_CONSTTIME is set)
510 */
511 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
512 {
513 BN_init(&local_p);
514 p = &local_p;
515 BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
516
517 BN_init(&local_q);
518 q = &local_q;
519 BN_with_flags(q, rsa->q, BN_FLG_CONSTTIME);
520 }
521 else
522 {
523 p = rsa->p;
524 q = rsa->q;
525 }
526
527 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE)
528 {
529 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_p, CRYPTO_LOCK_RSA, p, ctx))
530 error = 1;
531 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_q, CRYPTO_LOCK_RSA, q, ctx))
532 error = 1;
533 }
534
535 /* clean up */
536 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
537 {
538 BN_free(&local_p);
539 BN_free(&local_q);
540 }
541 if ( error )
542 goto err;
543 }
544
545 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
546 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
547 goto err;
548
549 /* compute I mod q */
550 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
551 {
552 c = &local_c;
553 BN_with_flags(c, I, BN_FLG_CONSTTIME);
554 if (!BN_mod(r1,c,rsa->q,ctx)) goto err;
555 }
556 else
557 {
558 if (!BN_mod(r1,I,rsa->q,ctx)) goto err;
559 }
560
561 /* compute r1^dmq1 mod q */
562 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
563 {
564 dmq1 = &local_dmq1;
565 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
566 }
567 else
568 dmq1 = rsa->dmq1;
569
570 if (!e_rsax_bn_mod_exp(m1,r1,dmq1,rsa->q,ctx,
571 rsa->_method_mod_q, e_rsax_get_ctx(rsa, 0, rsa->q) )) goto err;
572
573 /* compute I mod p */
574 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
575 {
576 c = &local_c;
577 BN_with_flags(c, I, BN_FLG_CONSTTIME);
578 if (!BN_mod(r1,c,rsa->p,ctx)) goto err;
579 }
580 else
581 {
582 if (!BN_mod(r1,I,rsa->p,ctx)) goto err;
583 }
584
585 /* compute r1^dmp1 mod p */
586 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
587 {
588 dmp1 = &local_dmp1;
589 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
590 }
591 else
592 dmp1 = rsa->dmp1;
593
594 if (!e_rsax_bn_mod_exp(r0,r1,dmp1,rsa->p,ctx,
595 rsa->_method_mod_p, e_rsax_get_ctx(rsa, 1, rsa->p) )) goto err;
596
597 if (!BN_sub(r0,r0,m1)) goto err;
598 /* This will help stop the size of r0 increasing, which does
599 * affect the multiply if it optimised for a power of 2 size */
600 if (BN_is_negative(r0))
601 if (!BN_add(r0,r0,rsa->p)) goto err;
602
603 if (!BN_mul(r1,r0,rsa->iqmp,ctx)) goto err;
604
605 /* Turn BN_FLG_CONSTTIME flag on before division operation */
606 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
607 {
608 pr1 = &local_r1;
609 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
610 }
611 else
612 pr1 = r1;
613 if (!BN_mod(r0,pr1,rsa->p,ctx)) goto err;
614
615 /* If p < q it is occasionally possible for the correction of
616 * adding 'p' if r0 is negative above to leave the result still
617 * negative. This can break the private key operations: the following
618 * second correction should *always* correct this rare occurrence.
619 * This will *never* happen with OpenSSL generated keys because
620 * they ensure p > q [steve]
621 */
622 if (BN_is_negative(r0))
623 if (!BN_add(r0,r0,rsa->p)) goto err;
624 if (!BN_mul(r1,r0,rsa->q,ctx)) goto err;
625 if (!BN_add(r0,r1,m1)) goto err;
626
627 if (rsa->e && rsa->n)
628 {
629 if (!e_rsax_bn_mod_exp(vrfy,r0,rsa->e,rsa->n,ctx,rsa->_method_mod_n, e_rsax_get_ctx(rsa, 2, rsa->n) ))
630 goto err;
631
632 /* If 'I' was greater than (or equal to) rsa->n, the operation
633 * will be equivalent to using 'I mod n'. However, the result of
634 * the verify will *always* be less than 'n' so we don't check
635 * for absolute equality, just congruency. */
636 if (!BN_sub(vrfy, vrfy, I)) goto err;
637 if (!BN_mod(vrfy, vrfy, rsa->n, ctx)) goto err;
638 if (BN_is_negative(vrfy))
639 if (!BN_add(vrfy, vrfy, rsa->n)) goto err;
640 if (!BN_is_zero(vrfy))
641 {
642 /* 'I' and 'vrfy' aren't congruent mod n. Don't leak
643 * miscalculated CRT output, just do a raw (slower)
644 * mod_exp and return that instead. */
645
646 BIGNUM local_d;
647 BIGNUM *d = NULL;
648
649 if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
650 {
651 d = &local_d;
652 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
653 }
654 else
655 d = rsa->d;
656 if (!e_rsax_bn_mod_exp(r0,I,d,rsa->n,ctx,
657 rsa->_method_mod_n, e_rsax_get_ctx(rsa, 2, rsa->n) )) goto err;
658 }
659 }
660 ret=1;
661
662 err:
663 BN_CTX_end(ctx);
664
665 return ret;
666 }
667 #endif /* !OPENSSL_NO_RSA */
668 #endif /* !COMPILE_RSAX */