1 /* $OpenBSD: rsa_eay.c,v 1.41 2016/06/30 02:02:06 bcook Exp $ */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
58 /* ====================================================================
59 * Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved.
61 * Redistribution and use in source and binary forms, with or without
62 * modification, are permitted provided that the following conditions
65 * 1. Redistributions of source code must retain the above copyright
66 * notice, this list of conditions and the following disclaimer.
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
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/)"
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.
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.
87 * 6. Redistributions of any form whatsoever must retain the following
89 * "This product includes software developed by the OpenSSL Project
90 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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 * ====================================================================
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).
115 #include <openssl/opensslconf.h>
117 #include <openssl/bn.h>
118 #include <openssl/err.h>
119 #include <openssl/rsa.h>
121 static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
122 unsigned char *to, RSA *rsa, int padding);
123 static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
124 unsigned char *to, RSA *rsa, int padding);
125 static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
126 unsigned char *to, RSA *rsa, int padding);
127 static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
128 unsigned char *to, RSA *rsa, int padding);
129 static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa, BN_CTX *ctx);
130 static int RSA_eay_init(RSA *rsa);
131 static int RSA_eay_finish(RSA *rsa);
133 static RSA_METHOD rsa_pkcs1_eay_meth = {
134 .name = "Eric Young's PKCS#1 RSA",
135 .rsa_pub_enc = RSA_eay_public_encrypt,
136 .rsa_pub_dec = RSA_eay_public_decrypt, /* signature verification */
137 .rsa_priv_enc = RSA_eay_private_encrypt, /* signing */
138 .rsa_priv_dec = RSA_eay_private_decrypt,
139 .rsa_mod_exp = RSA_eay_mod_exp,
140 .bn_mod_exp = BN_mod_exp_mont, /* XXX probably we should not use Montgomery if e == 3 */
141 .init = RSA_eay_init,
142 .finish = RSA_eay_finish,
146 RSA_PKCS1_SSLeay(void)
148 return &rsa_pkcs1_eay_meth;
152 RSA_eay_public_encrypt(int flen, const unsigned char *from, unsigned char *to,
153 RSA *rsa, int padding)
156 int i, j, k, num = 0, r = -1;
157 unsigned char *buf = NULL;
160 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
161 RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
165 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
166 RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
170 /* for large moduli, enforce exponent limit */
171 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
172 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
173 RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
178 if ((ctx = BN_CTX_new()) == NULL)
183 ret = BN_CTX_get(ctx);
184 num = BN_num_bytes(rsa->n);
187 if (f == NULL || ret == NULL || buf == NULL) {
188 RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, ERR_R_MALLOC_FAILURE);
193 case RSA_PKCS1_PADDING:
194 i = RSA_padding_add_PKCS1_type_2(buf, num, from, flen);
196 #ifndef OPENSSL_NO_SHA
197 case RSA_PKCS1_OAEP_PADDING:
198 i = RSA_padding_add_PKCS1_OAEP(buf, num, from, flen, NULL, 0);
201 case RSA_SSLV23_PADDING:
202 i = RSA_padding_add_SSLv23(buf, num, from, flen);
205 i = RSA_padding_add_none(buf, num, from, flen);
208 RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT,
209 RSA_R_UNKNOWN_PADDING_TYPE);
215 if (BN_bin2bn(buf, num, f) == NULL)
218 if (BN_ucmp(f, rsa->n) >= 0) {
219 /* usually the padding functions would catch this */
220 RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT,
221 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
225 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
226 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n,
227 CRYPTO_LOCK_RSA, rsa->n, ctx))
230 if (!rsa->meth->bn_mod_exp(ret, f,rsa->e, rsa->n, ctx,
234 /* put in leading 0 bytes if the number is less than the
235 * length of the modulus */
236 j = BN_num_bytes(ret);
237 i = BN_bn2bin(ret, &(to[num - j]));
238 for (k = 0; k < num - i; k++)
248 explicit_bzero(buf, num);
255 rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
258 int got_write_lock = 0;
261 CRYPTO_r_lock(CRYPTO_LOCK_RSA);
263 if (rsa->blinding == NULL) {
264 CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
265 CRYPTO_w_lock(CRYPTO_LOCK_RSA);
268 if (rsa->blinding == NULL)
269 rsa->blinding = RSA_setup_blinding(rsa, ctx);
276 CRYPTO_THREADID_current(&cur);
277 if (!CRYPTO_THREADID_cmp(&cur, BN_BLINDING_thread_id(ret))) {
278 /* rsa->blinding is ours! */
281 /* resort to rsa->mt_blinding instead */
283 * Instruct rsa_blinding_convert(), rsa_blinding_invert()
284 * that the BN_BLINDING is shared, meaning that accesses
285 * require locks, and that the blinding factor must be
286 * stored outside the BN_BLINDING
290 if (rsa->mt_blinding == NULL) {
291 if (!got_write_lock) {
292 CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
293 CRYPTO_w_lock(CRYPTO_LOCK_RSA);
297 if (rsa->mt_blinding == NULL)
298 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
300 ret = rsa->mt_blinding;
305 CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
307 CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
312 rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind, BN_CTX *ctx)
316 * Local blinding: store the unblinding factor
319 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
322 * Shared blinding: store the unblinding factor
323 * outside BN_BLINDING.
326 CRYPTO_w_lock(CRYPTO_LOCK_RSA_BLINDING);
327 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
328 CRYPTO_w_unlock(CRYPTO_LOCK_RSA_BLINDING);
334 rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind, BN_CTX *ctx)
337 * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
338 * will use the unblinding factor stored in BN_BLINDING.
339 * If BN_BLINDING is shared between threads, unblind must be non-null:
340 * BN_BLINDING_invert_ex will then use the local unblinding factor,
341 * and will only read the modulus from BN_BLINDING.
342 * In both cases it's safe to access the blinding without a lock.
344 return BN_BLINDING_invert_ex(f, unblind, b, ctx);
349 RSA_eay_private_encrypt(int flen, const unsigned char *from, unsigned char *to,
350 RSA *rsa, int padding)
352 BIGNUM *f, *ret, *res;
353 int i, j, k, num = 0, r = -1;
354 unsigned char *buf = NULL;
356 int local_blinding = 0;
358 * Used only if the blinding structure is shared. A non-NULL unblind
359 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
360 * the unblinding factor outside the blinding structure.
362 BIGNUM *unblind = NULL;
363 BN_BLINDING *blinding = NULL;
365 if ((ctx = BN_CTX_new()) == NULL)
370 ret = BN_CTX_get(ctx);
371 num = BN_num_bytes(rsa->n);
374 if (f == NULL || ret == NULL || buf == NULL) {
375 RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
380 case RSA_PKCS1_PADDING:
381 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
383 case RSA_X931_PADDING:
384 i = RSA_padding_add_X931(buf, num, from, flen);
387 i = RSA_padding_add_none(buf, num, from, flen);
389 case RSA_SSLV23_PADDING:
391 RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,
392 RSA_R_UNKNOWN_PADDING_TYPE);
398 if (BN_bin2bn(buf, num, f) == NULL)
401 if (BN_ucmp(f, rsa->n) >= 0) {
402 /* usually the padding functions would catch this */
403 RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,
404 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
408 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
409 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
410 if (blinding == NULL) {
411 RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,
412 ERR_R_INTERNAL_ERROR);
417 if (blinding != NULL) {
418 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
419 RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,
420 ERR_R_MALLOC_FAILURE);
423 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
427 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
428 (rsa->p != NULL && rsa->q != NULL && rsa->dmp1 != NULL &&
429 rsa->dmq1 != NULL && rsa->iqmp != NULL)) {
430 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
436 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME);
438 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
439 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n,
440 CRYPTO_LOCK_RSA, rsa->n, ctx))
443 if (!rsa->meth->bn_mod_exp(ret, f, &d, rsa->n, ctx,
444 rsa->_method_mod_n)) {
450 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
453 if (padding == RSA_X931_PADDING) {
454 BN_sub(f, rsa->n, ret);
455 if (BN_cmp(ret, f) > 0)
462 /* put in leading 0 bytes if the number is less than the
463 * length of the modulus */
464 j = BN_num_bytes(res);
465 i = BN_bn2bin(res, &(to[num - j]));
466 for (k = 0; k < num - i; k++)
476 explicit_bzero(buf, num);
483 RSA_eay_private_decrypt(int flen, const unsigned char *from, unsigned char *to,
484 RSA *rsa, int padding)
487 int j, num = 0, r = -1;
489 unsigned char *buf = NULL;
491 int local_blinding = 0;
493 * Used only if the blinding structure is shared. A non-NULL unblind
494 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
495 * the unblinding factor outside the blinding structure.
497 BIGNUM *unblind = NULL;
498 BN_BLINDING *blinding = NULL;
500 if ((ctx = BN_CTX_new()) == NULL)
505 ret = BN_CTX_get(ctx);
506 num = BN_num_bytes(rsa->n);
509 if (!f || !ret || !buf) {
510 RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
514 /* This check was for equality but PGP does evil things
515 * and chops off the top '0' bytes */
517 RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
518 RSA_R_DATA_GREATER_THAN_MOD_LEN);
522 /* make data into a big number */
523 if (BN_bin2bn(from, (int)flen, f) == NULL)
526 if (BN_ucmp(f, rsa->n) >= 0) {
527 RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
528 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
532 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
533 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
534 if (blinding == NULL) {
535 RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
536 ERR_R_INTERNAL_ERROR);
541 if (blinding != NULL) {
542 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
543 RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
544 ERR_R_MALLOC_FAILURE);
547 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
552 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
553 (rsa->p != NULL && rsa->q != NULL && rsa->dmp1 != NULL &&
554 rsa->dmq1 != NULL && rsa->iqmp != NULL)) {
555 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
561 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME);
563 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
564 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n,
565 CRYPTO_LOCK_RSA, rsa->n, ctx))
568 if (!rsa->meth->bn_mod_exp(ret, f, &d, rsa->n, ctx,
569 rsa->_method_mod_n)) {
575 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
579 j = BN_bn2bin(ret, p); /* j is only used with no-padding mode */
582 case RSA_PKCS1_PADDING:
583 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
585 #ifndef OPENSSL_NO_SHA
586 case RSA_PKCS1_OAEP_PADDING:
587 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
590 case RSA_SSLV23_PADDING:
591 r = RSA_padding_check_SSLv23(to, num, buf, j, num);
594 r = RSA_padding_check_none(to, num, buf, j, num);
597 RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
598 RSA_R_UNKNOWN_PADDING_TYPE);
602 RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,
603 RSA_R_PADDING_CHECK_FAILED);
611 explicit_bzero(buf, num);
617 /* signature verification */
619 RSA_eay_public_decrypt(int flen, const unsigned char *from, unsigned char *to,
620 RSA *rsa, int padding)
623 int i, num = 0, r = -1;
625 unsigned char *buf = NULL;
628 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
629 RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
633 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
634 RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
638 /* for large moduli, enforce exponent limit */
639 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
640 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
641 RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
646 if ((ctx = BN_CTX_new()) == NULL)
651 ret = BN_CTX_get(ctx);
652 num = BN_num_bytes(rsa->n);
655 if (!f || !ret || !buf) {
656 RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
660 /* This check was for equality but PGP does evil things
661 * and chops off the top '0' bytes */
663 RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,
664 RSA_R_DATA_GREATER_THAN_MOD_LEN);
668 if (BN_bin2bn(from, flen, f) == NULL)
671 if (BN_ucmp(f, rsa->n) >= 0) {
672 RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,
673 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
677 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
678 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n,
679 CRYPTO_LOCK_RSA, rsa->n, ctx))
682 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
686 if (padding == RSA_X931_PADDING && (ret->d[0] & 0xf) != 12)
687 if (!BN_sub(ret, rsa->n, ret))
691 i = BN_bn2bin(ret, p);
694 case RSA_PKCS1_PADDING:
695 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
697 case RSA_X931_PADDING:
698 r = RSA_padding_check_X931(to, num, buf, i, num);
701 r = RSA_padding_check_none(to, num, buf, i, num);
704 RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,
705 RSA_R_UNKNOWN_PADDING_TYPE);
709 RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,
710 RSA_R_PADDING_CHECK_FAILED);
718 explicit_bzero(buf, num);
725 RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
727 BIGNUM *r1, *m1, *vrfy;
728 BIGNUM dmp1, dmq1, c, pr1;
732 r1 = BN_CTX_get(ctx);
733 m1 = BN_CTX_get(ctx);
734 vrfy = BN_CTX_get(ctx);
735 if (r1 == NULL || m1 == NULL || vrfy == NULL) {
736 RSAerr(RSA_F_RSA_EAY_MOD_EXP, ERR_R_MALLOC_FAILURE);
744 * Make sure BN_mod_inverse in Montgomery intialization uses the
745 * BN_FLG_CONSTTIME flag
749 BN_with_flags(&p, rsa->p, BN_FLG_CONSTTIME);
750 BN_with_flags(&q, rsa->q, BN_FLG_CONSTTIME);
752 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
753 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_p,
754 CRYPTO_LOCK_RSA, &p, ctx) ||
755 !BN_MONT_CTX_set_locked(&rsa->_method_mod_q,
756 CRYPTO_LOCK_RSA, &q, ctx)) {
762 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
763 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n,
764 CRYPTO_LOCK_RSA, rsa->n, ctx))
767 /* compute I mod q */
769 BN_with_flags(&c, I, BN_FLG_CONSTTIME);
771 if (!BN_mod(r1, &c, rsa->q, ctx))
774 /* compute r1^dmq1 mod q */
776 BN_with_flags(&dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
778 if (!rsa->meth->bn_mod_exp(m1, r1, &dmq1, rsa->q, ctx,
782 /* compute I mod p */
783 BN_with_flags(&c, I, BN_FLG_CONSTTIME);
785 if (!BN_mod(r1, &c, rsa->p, ctx))
788 /* compute r1^dmp1 mod p */
790 BN_with_flags(&dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
792 if (!rsa->meth->bn_mod_exp(r0, r1, &dmp1, rsa->p, ctx,
796 if (!BN_sub(r0, r0, m1))
800 * This will help stop the size of r0 increasing, which does
801 * affect the multiply if it optimised for a power of 2 size
803 if (BN_is_negative(r0))
804 if (!BN_add(r0, r0, rsa->p))
807 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
810 /* Turn BN_FLG_CONSTTIME flag on before division operation */
812 BN_with_flags(&pr1, r1, BN_FLG_CONSTTIME);
814 if (!BN_mod(r0, &pr1, rsa->p, ctx))
818 * If p < q it is occasionally possible for the correction of
819 * adding 'p' if r0 is negative above to leave the result still
820 * negative. This can break the private key operations: the following
821 * second correction should *always* correct this rare occurrence.
822 * This will *never* happen with OpenSSL generated keys because
823 * they ensure p > q [steve]
825 if (BN_is_negative(r0))
826 if (!BN_add(r0, r0, rsa->p))
828 if (!BN_mul(r1, r0, rsa->q, ctx))
830 if (!BN_add(r0, r1, m1))
833 if (rsa->e && rsa->n) {
834 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
838 * If 'I' was greater than (or equal to) rsa->n, the operation
839 * will be equivalent to using 'I mod n'. However, the result of
840 * the verify will *always* be less than 'n' so we don't check
841 * for absolute equality, just congruency.
843 if (!BN_sub(vrfy, vrfy, I))
845 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
847 if (BN_is_negative(vrfy))
848 if (!BN_add(vrfy, vrfy, rsa->n))
850 if (!BN_is_zero(vrfy)) {
852 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
853 * miscalculated CRT output, just do a raw (slower)
854 * mod_exp and return that instead.
859 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME);
861 if (!rsa->meth->bn_mod_exp(r0, I, &d, rsa->n, ctx,
862 rsa->_method_mod_n)) {
874 RSA_eay_init(RSA *rsa)
876 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
881 RSA_eay_finish(RSA *rsa)
883 BN_MONT_CTX_free(rsa->_method_mod_n);
884 BN_MONT_CTX_free(rsa->_method_mod_p);
885 BN_MONT_CTX_free(rsa->_method_mod_q);