2 * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (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
10 #include "internal/cryptlib.h"
11 #include "crypto/bn.h"
12 #include "rsa_local.h"
13 #include "internal/constant_time.h"
15 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
16 unsigned char *to, RSA *rsa, int padding);
17 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
18 unsigned char *to, RSA *rsa, int padding);
19 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
20 unsigned char *to, RSA *rsa, int padding);
21 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
22 unsigned char *to, RSA *rsa, int padding);
23 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
25 static int rsa_ossl_init(RSA *rsa);
26 static int rsa_ossl_finish(RSA *rsa);
27 static RSA_METHOD rsa_pkcs1_ossl_meth = {
29 rsa_ossl_public_encrypt,
30 rsa_ossl_public_decrypt, /* signature verification */
31 rsa_ossl_private_encrypt, /* signing */
32 rsa_ossl_private_decrypt,
34 BN_mod_exp_mont, /* XXX probably we should not use Montgomery
38 RSA_FLAG_FIPS_METHOD, /* flags */
42 NULL, /* rsa_keygen */
43 NULL /* rsa_multi_prime_keygen */
46 static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth;
48 void RSA_set_default_method(const RSA_METHOD *meth)
50 default_RSA_meth = meth;
53 const RSA_METHOD *RSA_get_default_method(void)
55 return default_RSA_meth;
58 const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
60 return &rsa_pkcs1_ossl_meth;
63 const RSA_METHOD *RSA_null_method(void)
68 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
69 unsigned char *to, RSA *rsa, int padding)
72 int i, num = 0, r = -1;
73 unsigned char *buf = NULL;
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);
81 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
82 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
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);
94 if ((ctx = BN_CTX_new()) == NULL)
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);
107 case RSA_PKCS1_PADDING:
108 i = RSA_padding_add_PKCS1_type_2(buf, num, from, flen);
110 case RSA_PKCS1_OAEP_PADDING:
111 i = RSA_padding_add_PKCS1_OAEP(buf, num, from, flen, NULL, 0);
113 case RSA_SSLV23_PADDING:
114 i = RSA_padding_add_SSLv23(buf, num, from, flen);
117 i = RSA_padding_add_none(buf, num, from, flen);
120 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
126 if (BN_bin2bn(buf, num, f) == NULL)
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);
136 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
137 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
141 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
146 * BN_bn2binpad puts in leading 0 bytes if the number is less than
147 * the length of the modulus.
149 r = BN_bn2binpad(ret, to, num);
153 OPENSSL_clear_free(buf, num);
157 static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
161 CRYPTO_THREAD_write_lock(rsa->lock);
163 if (rsa->blinding == NULL) {
164 rsa->blinding = RSA_setup_blinding(rsa, ctx);
171 if (BN_BLINDING_is_current_thread(ret)) {
172 /* rsa->blinding is ours! */
176 /* resort to rsa->mt_blinding instead */
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
185 if (rsa->mt_blinding == NULL) {
186 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
188 ret = rsa->mt_blinding;
192 CRYPTO_THREAD_unlock(rsa->lock);
196 static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
199 if (unblind == NULL) {
201 * Local blinding: store the unblinding factor in BN_BLINDING.
203 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
206 * Shared blinding: store the unblinding factor outside BN_BLINDING.
211 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
212 BN_BLINDING_unlock(b);
218 static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
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.
229 return BN_BLINDING_invert_ex(f, unblind, b, ctx);
233 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
234 unsigned char *to, RSA *rsa, int padding)
236 BIGNUM *f, *ret, *res;
237 int i, num = 0, r = -1;
238 unsigned char *buf = NULL;
240 int local_blinding = 0;
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.
246 BIGNUM *unblind = NULL;
247 BN_BLINDING *blinding = NULL;
249 if ((ctx = BN_CTX_new()) == NULL)
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);
262 case RSA_PKCS1_PADDING:
263 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
265 case RSA_X931_PADDING:
266 i = RSA_padding_add_X931(buf, num, from, flen);
269 i = RSA_padding_add_none(buf, num, from, flen);
271 case RSA_SSLV23_PADDING:
273 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
279 if (BN_bin2bn(buf, num, f) == NULL)
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);
289 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
290 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
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);
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);
307 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
311 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
312 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
315 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
316 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
319 BIGNUM *d = BN_new();
321 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
324 if (rsa->d == NULL) {
325 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_MISSING_PRIVATE_KEY);
329 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
331 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
332 rsa->_method_mod_n)) {
336 /* We MUST free d before any further use of rsa->d */
341 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
344 if (padding == RSA_X931_PADDING) {
345 if (!BN_sub(f, rsa->n, ret))
347 if (BN_cmp(ret, f) > 0)
356 * BN_bn2binpad puts in leading 0 bytes if the number is less than
357 * the length of the modulus.
359 r = BN_bn2binpad(res, to, num);
363 OPENSSL_clear_free(buf, num);
367 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
368 unsigned char *to, RSA *rsa, int padding)
371 int j, num = 0, r = -1;
372 unsigned char *buf = NULL;
374 int local_blinding = 0;
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.
380 BIGNUM *unblind = NULL;
381 BN_BLINDING *blinding = NULL;
383 if ((ctx = BN_CTX_new()) == NULL)
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);
396 * This check was for equality but PGP does evil things and chops off the
400 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
401 RSA_R_DATA_GREATER_THAN_MOD_LEN);
405 /* make data into a big number */
406 if (BN_bin2bn(from, (int)flen, f) == NULL)
409 if (BN_ucmp(f, rsa->n) >= 0) {
410 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
411 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
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);
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);
428 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
433 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
434 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
437 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
438 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
441 BIGNUM *d = BN_new();
443 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
446 if (rsa->d == NULL) {
447 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_MISSING_PRIVATE_KEY);
451 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
453 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
454 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
459 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
460 rsa->_method_mod_n)) {
464 /* We MUST free d before any further use of rsa->d */
470 * ossl_bn_rsa_do_unblind() combines blinding inversion and
471 * 0-padded BN BE serialization
473 j = ossl_bn_rsa_do_unblind(ret, blinding, unblind, rsa->n, ctx,
478 j = BN_bn2binpad(ret, buf, num);
484 case RSA_PKCS1_PADDING:
485 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
487 case RSA_PKCS1_OAEP_PADDING:
488 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
490 case RSA_SSLV23_PADDING:
491 r = RSA_padding_check_SSLv23(to, num, buf, j, num);
494 memcpy(to, buf, (r = j));
497 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
500 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
501 err_clear_last_constant_time(1 & ~constant_time_msb(r));
506 OPENSSL_clear_free(buf, num);
510 /* signature verification */
511 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
512 unsigned char *to, RSA *rsa, int padding)
515 int i, num = 0, r = -1;
516 unsigned char *buf = NULL;
519 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
520 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
524 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
525 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
529 /* for large moduli, enforce exponent limit */
530 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
531 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
532 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
537 if ((ctx = BN_CTX_new()) == NULL)
541 ret = BN_CTX_get(ctx);
542 num = BN_num_bytes(rsa->n);
543 buf = OPENSSL_malloc(num);
544 if (ret == NULL || buf == NULL) {
545 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
550 * This check was for equality but PGP does evil things and chops off the
554 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
558 if (BN_bin2bn(from, flen, f) == NULL)
561 if (BN_ucmp(f, rsa->n) >= 0) {
562 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT,
563 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
567 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
568 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
572 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
576 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
577 if (!BN_sub(ret, rsa->n, ret))
580 i = BN_bn2binpad(ret, buf, num);
583 case RSA_PKCS1_PADDING:
584 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
586 case RSA_X931_PADDING:
587 r = RSA_padding_check_X931(to, num, buf, i, num);
590 memcpy(to, buf, (r = i));
593 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
597 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
602 OPENSSL_clear_free(buf, num);
606 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
608 BIGNUM *r1, *m1, *vrfy, *r2, *m[RSA_MAX_PRIME_NUM - 2];
609 int ret = 0, i, ex_primes = 0, smooth = 0;
610 RSA_PRIME_INFO *pinfo;
614 r1 = BN_CTX_get(ctx);
615 r2 = BN_CTX_get(ctx);
616 m1 = BN_CTX_get(ctx);
617 vrfy = BN_CTX_get(ctx);
621 if (rsa->version == RSA_ASN1_VERSION_MULTI
622 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
623 || ex_primes > RSA_MAX_PRIME_NUM - 2))
626 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
627 BIGNUM *factor = BN_new();
633 * Make sure BN_mod_inverse in Montgomery initialization uses the
634 * BN_FLG_CONSTTIME flag
636 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
637 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
639 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
640 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
645 for (i = 0; i < ex_primes; i++) {
646 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
647 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
648 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
654 * We MUST free |factor| before any further use of the prime factors
658 smooth = (ex_primes == 0)
659 && (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
660 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
663 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
664 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
670 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
671 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
672 * to limb width. So that at the very least if |I| is fully reduced,
673 * i.e. less than p*q, we can count on from-to round to perform
674 * below modulo operations on |I|. Unlike BN_mod it's constant time.
676 if (/* m1 = I moq q */
677 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
678 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
679 /* m1 = m1^dmq1 mod q */
680 || !BN_mod_exp_mont_consttime(m1, m1, rsa->dmq1, rsa->q, ctx,
683 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
684 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
685 /* r1 = r1^dmp1 mod p */
686 || !BN_mod_exp_mont_consttime(r1, r1, rsa->dmp1, rsa->p, ctx,
688 /* r1 = (r1 - m1) mod p */
690 * bn_mod_sub_fixed_top is not regular modular subtraction,
691 * it can tolerate subtrahend to be larger than modulus, but
692 * not bit-wise wider. This makes up for uncommon q>p case,
693 * when |m1| can be larger than |rsa->p|.
695 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
697 /* r1 = r1 * iqmp mod p */
698 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
699 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
701 /* r0 = r1 * q + m1 */
702 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
703 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
709 /* compute I mod q */
711 BIGNUM *c = BN_new();
714 BN_with_flags(c, I, BN_FLG_CONSTTIME);
716 if (!BN_mod(r1, c, rsa->q, ctx)) {
722 BIGNUM *dmq1 = BN_new();
727 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
729 /* compute r1^dmq1 mod q */
730 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
731 rsa->_method_mod_q)) {
736 /* We MUST free dmq1 before any further use of rsa->dmq1 */
740 /* compute I mod p */
741 if (!BN_mod(r1, c, rsa->p, ctx)) {
745 /* We MUST free c before any further use of I */
750 BIGNUM *dmp1 = BN_new();
753 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
755 /* compute r1^dmp1 mod p */
756 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
757 rsa->_method_mod_p)) {
761 /* We MUST free dmp1 before any further use of rsa->dmp1 */
766 * calculate m_i in multi-prime case
769 * 1. squash the following two loops and calculate |m_i| there.
770 * 2. remove cc and reuse |c|.
771 * 3. remove |dmq1| and |dmp1| in previous block and use |di|.
773 * If these things are done, the code will be more readable.
776 BIGNUM *di = BN_new(), *cc = BN_new();
778 if (cc == NULL || di == NULL) {
784 for (i = 0; i < ex_primes; i++) {
786 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
792 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
794 /* prepare c and d_i */
795 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
796 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
798 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
803 /* compute r1 ^ d_i mod r_i */
804 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
815 if (!BN_sub(r0, r0, m1))
818 * This will help stop the size of r0 increasing, which does affect the
819 * multiply if it optimised for a power of 2 size
821 if (BN_is_negative(r0))
822 if (!BN_add(r0, r0, rsa->p))
825 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
829 BIGNUM *pr1 = BN_new();
832 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
834 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
838 /* We MUST free pr1 before any further use of r1 */
843 * If p < q it is occasionally possible for the correction of adding 'p'
844 * if r0 is negative above to leave the result still negative. This can
845 * break the private key operations: the following second correction
846 * should *always* correct this rare occurrence. This will *never* happen
847 * with OpenSSL generated keys because they ensure p > q [steve]
849 if (BN_is_negative(r0))
850 if (!BN_add(r0, r0, rsa->p))
852 if (!BN_mul(r1, r0, rsa->q, ctx))
854 if (!BN_add(r0, r1, m1))
857 /* add m_i to m in multi-prime case */
859 BIGNUM *pr2 = BN_new();
864 for (i = 0; i < ex_primes; i++) {
865 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
866 if (!BN_sub(r1, m[i], r0)) {
871 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
876 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
878 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
883 if (BN_is_negative(r1))
884 if (!BN_add(r1, r1, pinfo->r)) {
888 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
892 if (!BN_add(r0, r0, r1)) {
901 if (rsa->e && rsa->n) {
902 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
903 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
908 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
913 * If 'I' was greater than (or equal to) rsa->n, the operation will
914 * be equivalent to using 'I mod n'. However, the result of the
915 * verify will *always* be less than 'n' so we don't check for
916 * absolute equality, just congruency.
918 if (!BN_sub(vrfy, vrfy, I))
920 if (BN_is_zero(vrfy)) {
923 goto err; /* not actually error */
925 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
927 if (BN_is_negative(vrfy))
928 if (!BN_add(vrfy, vrfy, rsa->n))
930 if (!BN_is_zero(vrfy)) {
932 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
933 * miscalculated CRT output, just do a raw (slower) mod_exp and
934 * return that instead.
937 BIGNUM *d = BN_new();
940 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
942 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
943 rsa->_method_mod_n)) {
947 /* We MUST free d before any further use of rsa->d */
952 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
953 * saves the day is that correction is highly unlike, and private key
954 * operations are customarily performed on blinded message. Which means
955 * that attacker won't observe correlation with chosen plaintext.
956 * Secondly, remaining code would still handle it in same computational
957 * time and even conceal memory access pattern around corrected top.
966 static int rsa_ossl_init(RSA *rsa)
968 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
972 static int rsa_ossl_finish(RSA *rsa)
975 RSA_PRIME_INFO *pinfo;
977 BN_MONT_CTX_free(rsa->_method_mod_n);
978 BN_MONT_CTX_free(rsa->_method_mod_p);
979 BN_MONT_CTX_free(rsa->_method_mod_q);
980 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
981 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
982 BN_MONT_CTX_free(pinfo->m);