2 * Copyright 1995-2018 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 "internal/bn_int.h"
14 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
15 unsigned char *to, RSA *rsa, int padding);
16 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
17 unsigned char *to, RSA *rsa, int padding);
18 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
19 unsigned char *to, RSA *rsa, int padding);
20 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
21 unsigned char *to, RSA *rsa, int padding);
22 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
24 static int rsa_ossl_init(RSA *rsa);
25 static int rsa_ossl_finish(RSA *rsa);
26 static RSA_METHOD rsa_pkcs1_ossl_meth = {
28 rsa_ossl_public_encrypt,
29 rsa_ossl_public_decrypt, /* signature verification */
30 rsa_ossl_private_encrypt, /* signing */
31 rsa_ossl_private_decrypt,
33 BN_mod_exp_mont, /* XXX probably we should not use Montgomery
37 RSA_FLAG_FIPS_METHOD, /* flags */
41 NULL, /* rsa_keygen */
42 NULL /* rsa_multi_prime_keygen */
45 static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth;
47 void RSA_set_default_method(const RSA_METHOD *meth)
49 default_RSA_meth = meth;
52 const RSA_METHOD *RSA_get_default_method(void)
54 return default_RSA_meth;
57 const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
59 return &rsa_pkcs1_ossl_meth;
62 const RSA_METHOD *RSA_null_method(void)
67 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
68 unsigned char *to, RSA *rsa, int padding)
71 int i, num = 0, r = -1;
72 unsigned char *buf = NULL;
75 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
76 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
80 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
81 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
85 /* for large moduli, enforce exponent limit */
86 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
87 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
88 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
93 if ((ctx = BN_CTX_new()) == NULL)
97 ret = BN_CTX_get(ctx);
98 num = BN_num_bytes(rsa->n);
99 buf = OPENSSL_malloc(num);
100 if (ret == NULL || buf == NULL) {
101 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, ERR_R_MALLOC_FAILURE);
106 case RSA_PKCS1_PADDING:
107 i = RSA_padding_add_PKCS1_type_2(buf, num, from, flen);
109 case RSA_PKCS1_OAEP_PADDING:
110 i = RSA_padding_add_PKCS1_OAEP(buf, num, from, flen, NULL, 0);
112 case RSA_SSLV23_PADDING:
113 i = RSA_padding_add_SSLv23(buf, num, from, flen);
116 i = RSA_padding_add_none(buf, num, from, flen);
119 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
125 if (BN_bin2bn(buf, num, f) == NULL)
128 if (BN_ucmp(f, rsa->n) >= 0) {
129 /* usually the padding functions would catch this */
130 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT,
131 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
135 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
136 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
140 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
145 * BN_bn2binpad puts in leading 0 bytes if the number is less than
146 * the length of the modulus.
148 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 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
326 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
327 rsa->_method_mod_n)) {
331 /* We MUST free d before any further use of rsa->d */
336 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
339 if (padding == RSA_X931_PADDING) {
340 if (!BN_sub(f, rsa->n, ret))
342 if (BN_cmp(ret, f) > 0)
351 * BN_bn2binpad puts in leading 0 bytes if the number is less than
352 * the length of the modulus.
354 r = BN_bn2binpad(res, to, num);
359 OPENSSL_clear_free(buf, num);
363 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
364 unsigned char *to, RSA *rsa, int padding)
367 int j, num = 0, r = -1;
368 unsigned char *buf = NULL;
370 int local_blinding = 0;
372 * Used only if the blinding structure is shared. A non-NULL unblind
373 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
374 * the unblinding factor outside the blinding structure.
376 BIGNUM *unblind = NULL;
377 BN_BLINDING *blinding = NULL;
379 if ((ctx = BN_CTX_new()) == NULL)
383 ret = BN_CTX_get(ctx);
384 num = BN_num_bytes(rsa->n);
385 buf = OPENSSL_malloc(num);
386 if (ret == NULL || buf == NULL) {
387 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
392 * This check was for equality but PGP does evil things and chops off the
396 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
397 RSA_R_DATA_GREATER_THAN_MOD_LEN);
401 /* make data into a big number */
402 if (BN_bin2bn(from, (int)flen, f) == NULL)
405 if (BN_ucmp(f, rsa->n) >= 0) {
406 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
407 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
411 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
412 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
413 if (blinding == NULL) {
414 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
419 if (blinding != NULL) {
420 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
421 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
424 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
429 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
430 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
433 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
434 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
437 BIGNUM *d = BN_new();
439 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
442 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
444 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
445 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
450 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
451 rsa->_method_mod_n)) {
455 /* We MUST free d before any further use of rsa->d */
460 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
463 j = BN_bn2binpad(ret, buf, num);
466 case RSA_PKCS1_PADDING:
467 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
469 case RSA_PKCS1_OAEP_PADDING:
470 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
472 case RSA_SSLV23_PADDING:
473 r = RSA_padding_check_SSLv23(to, num, buf, j, num);
476 memcpy(to, buf, (r = j));
479 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
483 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
489 OPENSSL_clear_free(buf, num);
493 /* signature verification */
494 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
495 unsigned char *to, RSA *rsa, int padding)
498 int i, num = 0, r = -1;
499 unsigned char *buf = NULL;
502 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
503 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
507 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
508 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
512 /* for large moduli, enforce exponent limit */
513 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
514 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
515 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
520 if ((ctx = BN_CTX_new()) == NULL)
524 ret = BN_CTX_get(ctx);
525 num = BN_num_bytes(rsa->n);
526 buf = OPENSSL_malloc(num);
527 if (ret == NULL || buf == NULL) {
528 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
533 * This check was for equality but PGP does evil things and chops off the
537 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
541 if (BN_bin2bn(from, flen, f) == NULL)
544 if (BN_ucmp(f, rsa->n) >= 0) {
545 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT,
546 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
550 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
551 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
555 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
559 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
560 if (!BN_sub(ret, rsa->n, ret))
563 i = BN_bn2binpad(ret, buf, num);
566 case RSA_PKCS1_PADDING:
567 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
569 case RSA_X931_PADDING:
570 r = RSA_padding_check_X931(to, num, buf, i, num);
573 memcpy(to, buf, (r = i));
576 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
580 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
586 OPENSSL_clear_free(buf, num);
590 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
592 BIGNUM *r1, *m1, *vrfy, *r2, *m[RSA_MAX_PRIME_NUM - 2];
593 int ret = 0, i, ex_primes = 0, smooth = 0;
594 RSA_PRIME_INFO *pinfo;
598 r1 = BN_CTX_get(ctx);
599 r2 = BN_CTX_get(ctx);
600 m1 = BN_CTX_get(ctx);
601 vrfy = BN_CTX_get(ctx);
605 if (rsa->version == RSA_ASN1_VERSION_MULTI
606 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
607 || ex_primes > RSA_MAX_PRIME_NUM - 2))
610 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
611 BIGNUM *factor = BN_new();
617 * Make sure BN_mod_inverse in Montgomery initialization uses the
618 * BN_FLG_CONSTTIME flag
620 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
621 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
623 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
624 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
629 for (i = 0; i < ex_primes; i++) {
630 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
631 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
632 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
638 * We MUST free |factor| before any further use of the prime factors
642 smooth = (ex_primes == 0)
643 && (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
644 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
647 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
648 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
654 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
655 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
656 * to limb width. So that at the very least if |I| is fully reduced,
657 * i.e. less than p*q, we can count on from-to round to perform
658 * below modulo operations on |I|. Unlike BN_mod it's constant time.
660 if (/* m1 = I moq q */
661 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
662 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
663 /* m1 = m1^dmq1 mod q */
664 || !BN_mod_exp_mont_consttime(m1, m1, rsa->dmq1, rsa->q, ctx,
667 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
668 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
669 /* r1 = r1^dmp1 mod p */
670 || !BN_mod_exp_mont_consttime(r1, r1, rsa->dmp1, rsa->p, ctx,
672 /* r1 = (r1 - m1) mod p */
674 * bn_mod_sub_fixed_top is not regular modular subtraction,
675 * it can tolerate subtrahend to be larger than modulus, but
676 * not bit-wise wider. This makes up for uncommon q>p case,
677 * when |m1| can be larger than |rsa->p|.
679 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
681 /* r1 = r1 * iqmp mod p */
682 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
683 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
685 /* r0 = r1 * q + m1 */
686 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
687 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
693 /* compute I mod q */
695 BIGNUM *c = BN_new();
698 BN_with_flags(c, I, BN_FLG_CONSTTIME);
700 if (!BN_mod(r1, c, rsa->q, ctx)) {
706 BIGNUM *dmq1 = BN_new();
711 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
713 /* compute r1^dmq1 mod q */
714 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
715 rsa->_method_mod_q)) {
720 /* We MUST free dmq1 before any further use of rsa->dmq1 */
724 /* compute I mod p */
725 if (!BN_mod(r1, c, rsa->p, ctx)) {
729 /* We MUST free c before any further use of I */
734 BIGNUM *dmp1 = BN_new();
737 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
739 /* compute r1^dmp1 mod p */
740 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
741 rsa->_method_mod_p)) {
745 /* We MUST free dmp1 before any further use of rsa->dmp1 */
750 * calculate m_i in multi-prime case
753 * 1. squash the following two loops and calculate |m_i| there.
754 * 2. remove cc and reuse |c|.
755 * 3. remove |dmq1| and |dmp1| in previous block and use |di|.
757 * If these things are done, the code will be more readable.
760 BIGNUM *di = BN_new(), *cc = BN_new();
762 if (cc == NULL || di == NULL) {
768 for (i = 0; i < ex_primes; i++) {
770 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
776 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
778 /* prepare c and d_i */
779 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
780 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
782 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
787 /* compute r1 ^ d_i mod r_i */
788 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
799 if (!BN_sub(r0, r0, m1))
802 * This will help stop the size of r0 increasing, which does affect the
803 * multiply if it optimised for a power of 2 size
805 if (BN_is_negative(r0))
806 if (!BN_add(r0, r0, rsa->p))
809 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
813 BIGNUM *pr1 = BN_new();
816 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
818 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
822 /* We MUST free pr1 before any further use of r1 */
827 * If p < q it is occasionally possible for the correction of adding 'p'
828 * if r0 is negative above to leave the result still negative. This can
829 * break the private key operations: the following second correction
830 * should *always* correct this rare occurrence. This will *never* happen
831 * with OpenSSL generated keys because they ensure p > q [steve]
833 if (BN_is_negative(r0))
834 if (!BN_add(r0, r0, rsa->p))
836 if (!BN_mul(r1, r0, rsa->q, ctx))
838 if (!BN_add(r0, r1, m1))
841 /* add m_i to m in multi-prime case */
843 BIGNUM *pr2 = BN_new();
848 for (i = 0; i < ex_primes; i++) {
849 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
850 if (!BN_sub(r1, m[i], r0)) {
855 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
860 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
862 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
867 if (BN_is_negative(r1))
868 if (!BN_add(r1, r1, pinfo->r)) {
872 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
876 if (!BN_add(r0, r0, r1)) {
885 if (rsa->e && rsa->n) {
886 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
887 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
892 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
897 * If 'I' was greater than (or equal to) rsa->n, the operation will
898 * be equivalent to using 'I mod n'. However, the result of the
899 * verify will *always* be less than 'n' so we don't check for
900 * absolute equality, just congruency.
902 if (!BN_sub(vrfy, vrfy, I))
904 if (BN_is_zero(vrfy)) {
907 goto err; /* not actually error */
909 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
911 if (BN_is_negative(vrfy))
912 if (!BN_add(vrfy, vrfy, rsa->n))
914 if (!BN_is_zero(vrfy)) {
916 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
917 * miscalculated CRT output, just do a raw (slower) mod_exp and
918 * return that instead.
921 BIGNUM *d = BN_new();
924 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
926 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
927 rsa->_method_mod_n)) {
931 /* We MUST free d before any further use of rsa->d */
936 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
937 * saves the day is that correction is highly unlike, and private key
938 * operations are customarily performed on blinded message. Which means
939 * that attacker won't observe correlation with chosen plaintext.
940 * Secondly, remaining code would still handle it in same computational
941 * time and even conceal memory access pattern around corrected top.
950 static int rsa_ossl_init(RSA *rsa)
952 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
956 static int rsa_ossl_finish(RSA *rsa)
959 RSA_PRIME_INFO *pinfo;
961 BN_MONT_CTX_free(rsa->_method_mod_n);
962 BN_MONT_CTX_free(rsa->_method_mod_p);
963 BN_MONT_CTX_free(rsa->_method_mod_q);
964 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
965 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
966 BN_MONT_CTX_free(pinfo->m);