1/*
2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include "internal/cryptlib.h"
11#include "crypto/bn.h"
12#include "rsa_local.h"
13#include "internal/constant_time.h"
14
15static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
16 unsigned char *to, RSA *rsa, int padding);
17static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
18 unsigned char *to, RSA *rsa, int padding);
19static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
20 unsigned char *to, RSA *rsa, int padding);
21static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
22 unsigned char *to, RSA *rsa, int padding);
23static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
24 BN_CTX *ctx);
25static int rsa_ossl_init(RSA *rsa);
26static int rsa_ossl_finish(RSA *rsa);
27static RSA_METHOD rsa_pkcs1_ossl_meth = {
28 "OpenSSL PKCS#1 RSA",
29 rsa_ossl_public_encrypt,
30 rsa_ossl_public_decrypt, /* signature verification */
31 rsa_ossl_private_encrypt, /* signing */
32 rsa_ossl_private_decrypt,
33 rsa_ossl_mod_exp,
34 BN_mod_exp_mont, /* XXX probably we should not use Montgomery
35 * if e == 3 */
36 rsa_ossl_init,
37 rsa_ossl_finish,
38 RSA_FLAG_FIPS_METHOD, /* flags */
39 NULL,
40 0, /* rsa_sign */
41 0, /* rsa_verify */
42 NULL, /* rsa_keygen */
43 NULL /* rsa_multi_prime_keygen */
44};
45
46static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth;
47
48void RSA_set_default_method(const RSA_METHOD *meth)
49{
50 default_RSA_meth = meth;
51}
52
53const RSA_METHOD *RSA_get_default_method(void)
54{
55 return default_RSA_meth;
56}
57
58const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
59{
60 return &rsa_pkcs1_ossl_meth;
61}
62
63const RSA_METHOD *RSA_null_method(void)
64{
65 return NULL;
66}
67
68static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
69 unsigned char *to, RSA *rsa, int padding)
70{
71 BIGNUM *f, *ret;
72 int i, num = 0, r = -1;
73 unsigned char *buf = NULL;
74 BN_CTX *ctx = NULL;
75
76 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
77 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
78 return -1;
79 }
80
81 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
82 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
83 return -1;
84 }
85
86 /* for large moduli, enforce exponent limit */
87 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
88 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
89 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
90 return -1;
91 }
92 }
93
94 if ((ctx = BN_CTX_new()) == NULL)
95 goto err;
96 BN_CTX_start(ctx);
97 f = BN_CTX_get(ctx);
98 ret = BN_CTX_get(ctx);
99 num = BN_num_bytes(rsa->n);
100 buf = OPENSSL_malloc(num);
101 if (ret == NULL || buf == NULL) {
102 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, ERR_R_MALLOC_FAILURE);
103 goto err;
104 }
105
106 switch (padding) {
107 case RSA_PKCS1_PADDING:
108 i = RSA_padding_add_PKCS1_type_2(buf, num, from, flen);
109 break;
110 case RSA_PKCS1_OAEP_PADDING:
111 i = RSA_padding_add_PKCS1_OAEP(buf, num, from, flen, NULL, 0);
112 break;
113 case RSA_SSLV23_PADDING:
114 i = RSA_padding_add_SSLv23(buf, num, from, flen);
115 break;
116 case RSA_NO_PADDING:
117 i = RSA_padding_add_none(buf, num, from, flen);
118 break;
119 default:
120 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
121 goto err;
122 }
123 if (i <= 0)
124 goto err;
125
126 if (BN_bin2bn(buf, num, f) == NULL)
127 goto err;
128
129 if (BN_ucmp(f, rsa->n) >= 0) {
130 /* usually the padding functions would catch this */
131 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT,
132 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
133 goto err;
134 }
135
136 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
137 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
138 rsa->n, ctx))
139 goto err;
140
141 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
142 rsa->_method_mod_n))
143 goto err;
144
145 /*
146 * BN_bn2binpad puts in leading 0 bytes if the number is less than
147 * the length of the modulus.
148 */
149 r = BN_bn2binpad(ret, to, num);
150 err:
151 BN_CTX_end(ctx);
152 BN_CTX_free(ctx);
153 OPENSSL_clear_free(buf, num);
154 return r;
155}
156
157static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
158{
159 BN_BLINDING *ret;
160
161 CRYPTO_THREAD_write_lock(rsa->lock);
162
163 if (rsa->blinding == NULL) {
164 rsa->blinding = RSA_setup_blinding(rsa, ctx);
165 }
166
167 ret = rsa->blinding;
168 if (ret == NULL)
169 goto err;
170
171 if (BN_BLINDING_is_current_thread(ret)) {
172 /* rsa->blinding is ours! */
173
174 *local = 1;
175 } else {
176 /* resort to rsa->mt_blinding instead */
177
178 /*
179 * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
180 * BN_BLINDING is shared, meaning that accesses require locks, and
181 * that the blinding factor must be stored outside the BN_BLINDING
182 */
183 *local = 0;
184
185 if (rsa->mt_blinding == NULL) {
186 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
187 }
188 ret = rsa->mt_blinding;
189 }
190
191 err:
192 CRYPTO_THREAD_unlock(rsa->lock);
193 return ret;
194}
195
196static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
197 BN_CTX *ctx)
198{
199 if (unblind == NULL) {
200 /*
201 * Local blinding: store the unblinding factor in BN_BLINDING.
202 */
203 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
204 } else {
205 /*
206 * Shared blinding: store the unblinding factor outside BN_BLINDING.
207 */
208 int ret;
209
210 BN_BLINDING_lock(b);
211 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
212 BN_BLINDING_unlock(b);
213
214 return ret;
215 }
216}
217
218static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
219 BN_CTX *ctx)
220{
221 /*
222 * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
223 * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
224 * is shared between threads, unblind must be non-null:
225 * BN_BLINDING_invert_ex will then use the local unblinding factor, and
226 * will only read the modulus from BN_BLINDING. In both cases it's safe
227 * to access the blinding without a lock.
228 */
229 return BN_BLINDING_invert_ex(f, unblind, b, ctx);
230}
231
232/* signing */
233static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
234 unsigned char *to, RSA *rsa, int padding)
235{
236 BIGNUM *f, *ret, *res;
237 int i, num = 0, r = -1;
238 unsigned char *buf = NULL;
239 BN_CTX *ctx = NULL;
240 int local_blinding = 0;
241 /*
242 * Used only if the blinding structure is shared. A non-NULL unblind
243 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
244 * the unblinding factor outside the blinding structure.
245 */
246 BIGNUM *unblind = NULL;
247 BN_BLINDING *blinding = NULL;
248
249 if ((ctx = BN_CTX_new()) == NULL)
250 goto err;
251 BN_CTX_start(ctx);
252 f = BN_CTX_get(ctx);
253 ret = BN_CTX_get(ctx);
254 num = BN_num_bytes(rsa->n);
255 buf = OPENSSL_malloc(num);
256 if (ret == NULL || buf == NULL) {
257 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
258 goto err;
259 }
260
261 switch (padding) {
262 case RSA_PKCS1_PADDING:
263 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
264 break;
265 case RSA_X931_PADDING:
266 i = RSA_padding_add_X931(buf, num, from, flen);
267 break;
268 case RSA_NO_PADDING:
269 i = RSA_padding_add_none(buf, num, from, flen);
270 break;
271 case RSA_SSLV23_PADDING:
272 default:
273 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
274 goto err;
275 }
276 if (i <= 0)
277 goto err;
278
279 if (BN_bin2bn(buf, num, f) == NULL)
280 goto err;
281
282 if (BN_ucmp(f, rsa->n) >= 0) {
283 /* usually the padding functions would catch this */
284 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT,
285 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
286 goto err;
287 }
288
289 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
290 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
291 rsa->n, ctx))
292 goto err;
293
294 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
295 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
296 if (blinding == NULL) {
297 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
298 goto err;
299 }
300 }
301
302 if (blinding != NULL) {
303 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
304 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
305 goto err;
306 }
307 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
308 goto err;
309 }
310
311 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
312 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
313 ((rsa->p != NULL) &&
314 (rsa->q != NULL) &&
315 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
316 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
317 goto err;
318 } else {
319 BIGNUM *d = BN_new();
320 if (d == NULL) {
321 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
322 goto err;
323 }
324 if (rsa->d == NULL) {
325 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_MISSING_PRIVATE_KEY);
326 BN_free(d);
327 goto err;
328 }
329 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
330
331 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
332 rsa->_method_mod_n)) {
333 BN_free(d);
334 goto err;
335 }
336 /* We MUST free d before any further use of rsa->d */
337 BN_free(d);
338 }
339
340 if (blinding)
341 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
342 goto err;
343
344 if (padding == RSA_X931_PADDING) {
345 if (!BN_sub(f, rsa->n, ret))
346 goto err;
347 if (BN_cmp(ret, f) > 0)
348 res = f;
349 else
350 res = ret;
351 } else {
352 res = ret;
353 }
354
355 /*
356 * BN_bn2binpad puts in leading 0 bytes if the number is less than
357 * the length of the modulus.
358 */
359 r = BN_bn2binpad(res, to, num);
360 err:
361 BN_CTX_end(ctx);
362 BN_CTX_free(ctx);
363 OPENSSL_clear_free(buf, num);
364 return r;
365}
366
367static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
368 unsigned char *to, RSA *rsa, int padding)
369{
370 BIGNUM *f, *ret;
371 int j, num = 0, r = -1;
372 unsigned char *buf = NULL;
373 BN_CTX *ctx = NULL;
374 int local_blinding = 0;
375 /*
376 * Used only if the blinding structure is shared. A non-NULL unblind
377 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
378 * the unblinding factor outside the blinding structure.
379 */
380 BIGNUM *unblind = NULL;
381 BN_BLINDING *blinding = NULL;
382
383 if ((ctx = BN_CTX_new()) == NULL)
384 goto err;
385 BN_CTX_start(ctx);
386 f = BN_CTX_get(ctx);
387 ret = BN_CTX_get(ctx);
388 num = BN_num_bytes(rsa->n);
389 buf = OPENSSL_malloc(num);
390 if (ret == NULL || buf == NULL) {
391 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
392 goto err;
393 }
394
395 /*
396 * This check was for equality but PGP does evil things and chops off the
397 * top '0' bytes
398 */
399 if (flen > num) {
400 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
401 RSA_R_DATA_GREATER_THAN_MOD_LEN);
402 goto err;
403 }
404
405 /* make data into a big number */
406 if (BN_bin2bn(from, (int)flen, f) == NULL)
407 goto err;
408
409 if (BN_ucmp(f, rsa->n) >= 0) {
410 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
411 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
412 goto err;
413 }
414
415 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
416 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
417 if (blinding == NULL) {
418 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
419 goto err;
420 }
421 }
422
423 if (blinding != NULL) {
424 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
425 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
426 goto err;
427 }
428 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
429 goto err;
430 }
431
432 /* do the decrypt */
433 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
434 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
435 ((rsa->p != NULL) &&
436 (rsa->q != NULL) &&
437 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
438 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
439 goto err;
440 } else {
441 BIGNUM *d = BN_new();
442 if (d == NULL) {
443 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
444 goto err;
445 }
446 if (rsa->d == NULL) {
447 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_MISSING_PRIVATE_KEY);
448 BN_free(d);
449 goto err;
450 }
451 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
452
453 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
454 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
455 rsa->n, ctx)) {
456 BN_free(d);
457 goto err;
458 }
459 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
460 rsa->_method_mod_n)) {
461 BN_free(d);
462 goto err;
463 }
464 /* We MUST free d before any further use of rsa->d */
465 BN_free(d);
466 }
467
468 if (blinding)
469 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
470 goto err;
471
472 j = BN_bn2binpad(ret, buf, num);
473 if (j < 0)
474 goto err;
475
476 switch (padding) {
477 case RSA_PKCS1_PADDING:
478 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
479 break;
480 case RSA_PKCS1_OAEP_PADDING:
481 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
482 break;
483 case RSA_SSLV23_PADDING:
484 r = RSA_padding_check_SSLv23(to, num, buf, j, num);
485 break;
486 case RSA_NO_PADDING:
487 memcpy(to, buf, (r = j));
488 break;
489 default:
490 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
491 goto err;
492 }
493 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
494 err_clear_last_constant_time(1 & ~constant_time_msb(r));
495
496 err:
497 BN_CTX_end(ctx);
498 BN_CTX_free(ctx);
499 OPENSSL_clear_free(buf, num);
500 return r;
501}
502
503/* signature verification */
504static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
505 unsigned char *to, RSA *rsa, int padding)
506{
507 BIGNUM *f, *ret;
508 int i, num = 0, r = -1;
509 unsigned char *buf = NULL;
510 BN_CTX *ctx = NULL;
511
512 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
513 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
514 return -1;
515 }
516
517 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
518 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
519 return -1;
520 }
521
522 /* for large moduli, enforce exponent limit */
523 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
524 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
525 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
526 return -1;
527 }
528 }
529
530 if ((ctx = BN_CTX_new()) == NULL)
531 goto err;
532 BN_CTX_start(ctx);
533 f = BN_CTX_get(ctx);
534 ret = BN_CTX_get(ctx);
535 num = BN_num_bytes(rsa->n);
536 buf = OPENSSL_malloc(num);
537 if (ret == NULL || buf == NULL) {
538 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
539 goto err;
540 }
541
542 /*
543 * This check was for equality but PGP does evil things and chops off the
544 * top '0' bytes
545 */
546 if (flen > num) {
547 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
548 goto err;
549 }
550
551 if (BN_bin2bn(from, flen, f) == NULL)
552 goto err;
553
554 if (BN_ucmp(f, rsa->n) >= 0) {
555 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT,
556 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
557 goto err;
558 }
559
560 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
561 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
562 rsa->n, ctx))
563 goto err;
564
565 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
566 rsa->_method_mod_n))
567 goto err;
568
569 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
570 if (!BN_sub(ret, rsa->n, ret))
571 goto err;
572
573 i = BN_bn2binpad(ret, buf, num);
574 if (i < 0)
575 goto err;
576
577 switch (padding) {
578 case RSA_PKCS1_PADDING:
579 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
580 break;
581 case RSA_X931_PADDING:
582 r = RSA_padding_check_X931(to, num, buf, i, num);
583 break;
584 case RSA_NO_PADDING:
585 memcpy(to, buf, (r = i));
586 break;
587 default:
588 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
589 goto err;
590 }
591 if (r < 0)
592 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
593
594 err:
595 BN_CTX_end(ctx);
596 BN_CTX_free(ctx);
597 OPENSSL_clear_free(buf, num);
598 return r;
599}
600
601static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
602{
603 BIGNUM *r1, *m1, *vrfy, *r2, *m[RSA_MAX_PRIME_NUM - 2];
604 int ret = 0, i, ex_primes = 0, smooth = 0;
605 RSA_PRIME_INFO *pinfo;
606
607 BN_CTX_start(ctx);
608
609 r1 = BN_CTX_get(ctx);
610 r2 = BN_CTX_get(ctx);
611 m1 = BN_CTX_get(ctx);
612 vrfy = BN_CTX_get(ctx);
613 if (vrfy == NULL)
614 goto err;
615
616 if (rsa->version == RSA_ASN1_VERSION_MULTI
617 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
618 || ex_primes > RSA_MAX_PRIME_NUM - 2))
619 goto err;
620
621 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
622 BIGNUM *factor = BN_new();
623
624 if (factor == NULL)
625 goto err;
626
627 /*
628 * Make sure BN_mod_inverse in Montgomery initialization uses the
629 * BN_FLG_CONSTTIME flag
630 */
631 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
632 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
633 factor, ctx))
634 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
635 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
636 factor, ctx))) {
637 BN_free(factor);
638 goto err;
639 }
640 for (i = 0; i < ex_primes; i++) {
641 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
642 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
643 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
644 BN_free(factor);
645 goto err;
646 }
647 }
648 /*
649 * We MUST free |factor| before any further use of the prime factors
650 */
651 BN_free(factor);
652
653 smooth = (ex_primes == 0)
654 && (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
655 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
656 }
657
658 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
659 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
660 rsa->n, ctx))
661 goto err;
662
663 if (smooth) {
664 /*
665 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
666 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
667 * to limb width. So that at the very least if |I| is fully reduced,
668 * i.e. less than p*q, we can count on from-to round to perform
669 * below modulo operations on |I|. Unlike BN_mod it's constant time.
670 */
671 if (/* m1 = I moq q */
672 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
673 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
674 /* m1 = m1^dmq1 mod q */
675 || !BN_mod_exp_mont_consttime(m1, m1, rsa->dmq1, rsa->q, ctx,
676 rsa->_method_mod_q)
677 /* r1 = I mod p */
678 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
679 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
680 /* r1 = r1^dmp1 mod p */
681 || !BN_mod_exp_mont_consttime(r1, r1, rsa->dmp1, rsa->p, ctx,
682 rsa->_method_mod_p)
683 /* r1 = (r1 - m1) mod p */
684 /*
685 * bn_mod_sub_fixed_top is not regular modular subtraction,
686 * it can tolerate subtrahend to be larger than modulus, but
687 * not bit-wise wider. This makes up for uncommon q>p case,
688 * when |m1| can be larger than |rsa->p|.
689 */
690 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
691
692 /* r1 = r1 * iqmp mod p */
693 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
694 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
695 ctx)
696 /* r0 = r1 * q + m1 */
697 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
698 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
699 goto err;
700
701 goto tail;
702 }
703
704 /* compute I mod q */
705 {
706 BIGNUM *c = BN_new();
707 if (c == NULL)
708 goto err;
709 BN_with_flags(c, I, BN_FLG_CONSTTIME);
710
711 if (!BN_mod(r1, c, rsa->q, ctx)) {
712 BN_free(c);
713 goto err;
714 }
715
716 {
717 BIGNUM *dmq1 = BN_new();
718 if (dmq1 == NULL) {
719 BN_free(c);
720 goto err;
721 }
722 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
723
724 /* compute r1^dmq1 mod q */
725 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
726 rsa->_method_mod_q)) {
727 BN_free(c);
728 BN_free(dmq1);
729 goto err;
730 }
731 /* We MUST free dmq1 before any further use of rsa->dmq1 */
732 BN_free(dmq1);
733 }
734
735 /* compute I mod p */
736 if (!BN_mod(r1, c, rsa->p, ctx)) {
737 BN_free(c);
738 goto err;
739 }
740 /* We MUST free c before any further use of I */
741 BN_free(c);
742 }
743
744 {
745 BIGNUM *dmp1 = BN_new();
746 if (dmp1 == NULL)
747 goto err;
748 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
749
750 /* compute r1^dmp1 mod p */
751 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
752 rsa->_method_mod_p)) {
753 BN_free(dmp1);
754 goto err;
755 }
756 /* We MUST free dmp1 before any further use of rsa->dmp1 */
757 BN_free(dmp1);
758 }
759
760 /*
761 * calculate m_i in multi-prime case
762 *
763 * TODO:
764 * 1. squash the following two loops and calculate |m_i| there.
765 * 2. remove cc and reuse |c|.
766 * 3. remove |dmq1| and |dmp1| in previous block and use |di|.
767 *
768 * If these things are done, the code will be more readable.
769 */
770 if (ex_primes > 0) {
771 BIGNUM *di = BN_new(), *cc = BN_new();
772
773 if (cc == NULL || di == NULL) {
774 BN_free(cc);
775 BN_free(di);
776 goto err;
777 }
778
779 for (i = 0; i < ex_primes; i++) {
780 /* prepare m_i */
781 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
782 BN_free(cc);
783 BN_free(di);
784 goto err;
785 }
786
787 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
788
789 /* prepare c and d_i */
790 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
791 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
792
793 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
794 BN_free(cc);
795 BN_free(di);
796 goto err;
797 }
798 /* compute r1 ^ d_i mod r_i */
799 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
800 BN_free(cc);
801 BN_free(di);
802 goto err;
803 }
804 }
805
806 BN_free(cc);
807 BN_free(di);
808 }
809
810 if (!BN_sub(r0, r0, m1))
811 goto err;
812 /*
813 * This will help stop the size of r0 increasing, which does affect the
814 * multiply if it optimised for a power of 2 size
815 */
816 if (BN_is_negative(r0))
817 if (!BN_add(r0, r0, rsa->p))
818 goto err;
819
820 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
821 goto err;
822
823 {
824 BIGNUM *pr1 = BN_new();
825 if (pr1 == NULL)
826 goto err;
827 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
828
829 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
830 BN_free(pr1);
831 goto err;
832 }
833 /* We MUST free pr1 before any further use of r1 */
834 BN_free(pr1);
835 }
836
837 /*
838 * If p < q it is occasionally possible for the correction of adding 'p'
839 * if r0 is negative above to leave the result still negative. This can
840 * break the private key operations: the following second correction
841 * should *always* correct this rare occurrence. This will *never* happen
842 * with OpenSSL generated keys because they ensure p > q [steve]
843 */
844 if (BN_is_negative(r0))
845 if (!BN_add(r0, r0, rsa->p))
846 goto err;
847 if (!BN_mul(r1, r0, rsa->q, ctx))
848 goto err;
849 if (!BN_add(r0, r1, m1))
850 goto err;
851
852 /* add m_i to m in multi-prime case */
853 if (ex_primes > 0) {
854 BIGNUM *pr2 = BN_new();
855
856 if (pr2 == NULL)
857 goto err;
858
859 for (i = 0; i < ex_primes; i++) {
860 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
861 if (!BN_sub(r1, m[i], r0)) {
862 BN_free(pr2);
863 goto err;
864 }
865
866 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
867 BN_free(pr2);
868 goto err;
869 }
870
871 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
872
873 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
874 BN_free(pr2);
875 goto err;
876 }
877
878 if (BN_is_negative(r1))
879 if (!BN_add(r1, r1, pinfo->r)) {
880 BN_free(pr2);
881 goto err;
882 }
883 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
884 BN_free(pr2);
885 goto err;
886 }
887 if (!BN_add(r0, r0, r1)) {
888 BN_free(pr2);
889 goto err;
890 }
891 }
892 BN_free(pr2);
893 }
894
895 tail:
896 if (rsa->e && rsa->n) {
897 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
898 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
899 rsa->_method_mod_n))
900 goto err;
901 } else {
902 bn_correct_top(r0);
903 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
904 rsa->_method_mod_n))
905 goto err;
906 }
907 /*
908 * If 'I' was greater than (or equal to) rsa->n, the operation will
909 * be equivalent to using 'I mod n'. However, the result of the
910 * verify will *always* be less than 'n' so we don't check for
911 * absolute equality, just congruency.
912 */
913 if (!BN_sub(vrfy, vrfy, I))
914 goto err;
915 if (BN_is_zero(vrfy)) {
916 bn_correct_top(r0);
917 ret = 1;
918 goto err; /* not actually error */
919 }
920 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
921 goto err;
922 if (BN_is_negative(vrfy))
923 if (!BN_add(vrfy, vrfy, rsa->n))
924 goto err;
925 if (!BN_is_zero(vrfy)) {
926 /*
927 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
928 * miscalculated CRT output, just do a raw (slower) mod_exp and
929 * return that instead.
930 */
931
932 BIGNUM *d = BN_new();
933 if (d == NULL)
934 goto err;
935 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
936
937 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
938 rsa->_method_mod_n)) {
939 BN_free(d);
940 goto err;
941 }
942 /* We MUST free d before any further use of rsa->d */
943 BN_free(d);
944 }
945 }
946 /*
947 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
948 * saves the day is that correction is highly unlike, and private key
949 * operations are customarily performed on blinded message. Which means
950 * that attacker won't observe correlation with chosen plaintext.
951 * Secondly, remaining code would still handle it in same computational
952 * time and even conceal memory access pattern around corrected top.
953 */
954 bn_correct_top(r0);
955 ret = 1;
956 err:
957 BN_CTX_end(ctx);
958 return ret;
959}
960
961static int rsa_ossl_init(RSA *rsa)
962{
963 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
964 return 1;
965}
966
967static int rsa_ossl_finish(RSA *rsa)
968{
969 int i;
970 RSA_PRIME_INFO *pinfo;
971
972 BN_MONT_CTX_free(rsa->_method_mod_n);
973 BN_MONT_CTX_free(rsa->_method_mod_p);
974 BN_MONT_CTX_free(rsa->_method_mod_q);
975 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
976 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
977 BN_MONT_CTX_free(pinfo->m);
978 }
979 return 1;
980}
981