2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
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
11 * RSA low level APIs are deprecated for public use, but still ok for
14 #include "internal/deprecated.h"
16 #include "internal/cryptlib.h"
17 #include "crypto/bn.h"
18 #include "rsa_local.h"
19 #include "internal/constant_time.h"
21 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
22 unsigned char *to, RSA *rsa, int padding);
23 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
24 unsigned char *to, RSA *rsa, int padding);
25 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
26 unsigned char *to, RSA *rsa, int padding);
27 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
28 unsigned char *to, RSA *rsa, int padding);
29 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
31 static int rsa_ossl_init(RSA *rsa);
32 static int rsa_ossl_finish(RSA *rsa);
33 static RSA_METHOD rsa_pkcs1_ossl_meth = {
35 rsa_ossl_public_encrypt,
36 rsa_ossl_public_decrypt, /* signature verification */
37 rsa_ossl_private_encrypt, /* signing */
38 rsa_ossl_private_decrypt,
40 BN_mod_exp_mont, /* XXX probably we should not use Montgomery
44 RSA_FLAG_FIPS_METHOD, /* flags */
48 NULL, /* rsa_keygen */
49 NULL /* rsa_multi_prime_keygen */
52 static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth;
54 void RSA_set_default_method(const RSA_METHOD *meth)
56 default_RSA_meth = meth;
59 const RSA_METHOD *RSA_get_default_method(void)
61 return default_RSA_meth;
64 const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
66 return &rsa_pkcs1_ossl_meth;
69 const RSA_METHOD *RSA_null_method(void)
74 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
75 unsigned char *to, RSA *rsa, int padding)
78 int i, num = 0, r = -1;
79 unsigned char *buf = NULL;
82 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
83 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
87 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
88 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
92 /* for large moduli, enforce exponent limit */
93 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
94 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
95 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
100 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
104 ret = BN_CTX_get(ctx);
105 num = BN_num_bytes(rsa->n);
106 buf = OPENSSL_malloc(num);
107 if (ret == NULL || buf == NULL) {
108 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, ERR_R_MALLOC_FAILURE);
113 case RSA_PKCS1_PADDING:
114 i = rsa_padding_add_PKCS1_type_2_with_libctx(rsa->libctx, buf, num,
117 case RSA_PKCS1_OAEP_PADDING:
118 i = rsa_padding_add_PKCS1_OAEP_mgf1_with_libctx(rsa->libctx, buf, num,
123 case RSA_SSLV23_PADDING:
124 i = rsa_padding_add_SSLv23_with_libctx(rsa->libctx, buf, num, from,
129 i = RSA_padding_add_none(buf, num, from, flen);
132 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
138 if (BN_bin2bn(buf, num, f) == NULL)
141 if (BN_ucmp(f, rsa->n) >= 0) {
142 /* usually the padding functions would catch this */
143 RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT,
144 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
148 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
149 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
153 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
158 * BN_bn2binpad puts in leading 0 bytes if the number is less than
159 * the length of the modulus.
161 r = BN_bn2binpad(ret, to, num);
165 OPENSSL_clear_free(buf, num);
169 static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
173 CRYPTO_THREAD_write_lock(rsa->lock);
175 if (rsa->blinding == NULL) {
176 rsa->blinding = RSA_setup_blinding(rsa, ctx);
183 if (BN_BLINDING_is_current_thread(ret)) {
184 /* rsa->blinding is ours! */
188 /* resort to rsa->mt_blinding instead */
191 * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
192 * BN_BLINDING is shared, meaning that accesses require locks, and
193 * that the blinding factor must be stored outside the BN_BLINDING
197 if (rsa->mt_blinding == NULL) {
198 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
200 ret = rsa->mt_blinding;
204 CRYPTO_THREAD_unlock(rsa->lock);
208 static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
211 if (unblind == NULL) {
213 * Local blinding: store the unblinding factor in BN_BLINDING.
215 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
218 * Shared blinding: store the unblinding factor outside BN_BLINDING.
223 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
224 BN_BLINDING_unlock(b);
230 static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
234 * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
235 * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
236 * is shared between threads, unblind must be non-null:
237 * BN_BLINDING_invert_ex will then use the local unblinding factor, and
238 * will only read the modulus from BN_BLINDING. In both cases it's safe
239 * to access the blinding without a lock.
241 return BN_BLINDING_invert_ex(f, unblind, b, ctx);
245 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
246 unsigned char *to, RSA *rsa, int padding)
248 BIGNUM *f, *ret, *res;
249 int i, num = 0, r = -1;
250 unsigned char *buf = NULL;
252 int local_blinding = 0;
254 * Used only if the blinding structure is shared. A non-NULL unblind
255 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
256 * the unblinding factor outside the blinding structure.
258 BIGNUM *unblind = NULL;
259 BN_BLINDING *blinding = NULL;
261 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
265 ret = BN_CTX_get(ctx);
266 num = BN_num_bytes(rsa->n);
267 buf = OPENSSL_malloc(num);
268 if (ret == NULL || buf == NULL) {
269 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
274 case RSA_PKCS1_PADDING:
275 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
277 case RSA_X931_PADDING:
278 i = RSA_padding_add_X931(buf, num, from, flen);
281 i = RSA_padding_add_none(buf, num, from, flen);
283 case RSA_SSLV23_PADDING:
285 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
291 if (BN_bin2bn(buf, num, f) == NULL)
294 if (BN_ucmp(f, rsa->n) >= 0) {
295 /* usually the padding functions would catch this */
296 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT,
297 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
301 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
302 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
306 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
307 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
308 if (blinding == NULL) {
309 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
314 if (blinding != NULL) {
315 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
316 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
319 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
323 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
324 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
327 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
328 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
331 BIGNUM *d = BN_new();
333 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
336 if (rsa->d == NULL) {
337 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_MISSING_PRIVATE_KEY);
341 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
343 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
344 rsa->_method_mod_n)) {
348 /* We MUST free d before any further use of rsa->d */
353 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
356 if (padding == RSA_X931_PADDING) {
357 if (!BN_sub(f, rsa->n, ret))
359 if (BN_cmp(ret, f) > 0)
368 * BN_bn2binpad puts in leading 0 bytes if the number is less than
369 * the length of the modulus.
371 r = BN_bn2binpad(res, to, num);
375 OPENSSL_clear_free(buf, num);
379 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
380 unsigned char *to, RSA *rsa, int padding)
383 int j, num = 0, r = -1;
384 unsigned char *buf = NULL;
386 int local_blinding = 0;
388 * Used only if the blinding structure is shared. A non-NULL unblind
389 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
390 * the unblinding factor outside the blinding structure.
392 BIGNUM *unblind = NULL;
393 BN_BLINDING *blinding = NULL;
395 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
399 ret = BN_CTX_get(ctx);
400 num = BN_num_bytes(rsa->n);
401 buf = OPENSSL_malloc(num);
402 if (ret == NULL || buf == NULL) {
403 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
408 * This check was for equality but PGP does evil things and chops off the
412 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
413 RSA_R_DATA_GREATER_THAN_MOD_LEN);
417 /* make data into a big number */
418 if (BN_bin2bn(from, (int)flen, f) == NULL)
421 if (BN_ucmp(f, rsa->n) >= 0) {
422 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
423 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
427 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
428 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
429 if (blinding == NULL) {
430 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
435 if (blinding != NULL) {
436 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
437 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
440 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
445 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
446 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
449 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
450 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
453 BIGNUM *d = BN_new();
455 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
458 if (rsa->d == NULL) {
459 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_MISSING_PRIVATE_KEY);
463 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
465 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
466 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
471 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
472 rsa->_method_mod_n)) {
476 /* We MUST free d before any further use of rsa->d */
481 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
484 j = BN_bn2binpad(ret, buf, num);
489 case RSA_PKCS1_PADDING:
490 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
492 case RSA_PKCS1_OAEP_PADDING:
493 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
496 case RSA_SSLV23_PADDING:
497 r = RSA_padding_check_SSLv23(to, num, buf, j, num);
501 memcpy(to, buf, (r = j));
504 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
509 * This trick doesn't work in the FIPS provider because libcrypto manages
510 * the error stack. Instead we opt not to put an error on the stack at all
511 * in case of padding failure in the FIPS provider.
513 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
514 err_clear_last_constant_time(1 & ~constant_time_msb(r));
520 OPENSSL_clear_free(buf, num);
524 /* signature verification */
525 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
526 unsigned char *to, RSA *rsa, int padding)
529 int i, num = 0, r = -1;
530 unsigned char *buf = NULL;
533 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
534 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
538 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
539 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
543 /* for large moduli, enforce exponent limit */
544 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
545 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
546 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
551 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
555 ret = BN_CTX_get(ctx);
556 num = BN_num_bytes(rsa->n);
557 buf = OPENSSL_malloc(num);
558 if (ret == NULL || buf == NULL) {
559 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
564 * This check was for equality but PGP does evil things and chops off the
568 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
572 if (BN_bin2bn(from, flen, f) == NULL)
575 if (BN_ucmp(f, rsa->n) >= 0) {
576 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT,
577 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
581 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
582 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
586 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
590 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
591 if (!BN_sub(ret, rsa->n, ret))
594 i = BN_bn2binpad(ret, buf, num);
599 case RSA_PKCS1_PADDING:
600 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
602 case RSA_X931_PADDING:
603 r = RSA_padding_check_X931(to, num, buf, i, num);
606 memcpy(to, buf, (r = i));
609 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
613 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
618 OPENSSL_clear_free(buf, num);
622 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
624 BIGNUM *r1, *m1, *vrfy;
625 int ret = 0, smooth = 0;
627 BIGNUM *r2, *m[RSA_MAX_PRIME_NUM - 2];
628 int i, ex_primes = 0;
629 RSA_PRIME_INFO *pinfo;
634 r1 = BN_CTX_get(ctx);
636 r2 = BN_CTX_get(ctx);
638 m1 = BN_CTX_get(ctx);
639 vrfy = BN_CTX_get(ctx);
644 if (rsa->version == RSA_ASN1_VERSION_MULTI
645 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
646 || ex_primes > RSA_MAX_PRIME_NUM - 2))
650 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
651 BIGNUM *factor = BN_new();
657 * Make sure BN_mod_inverse in Montgomery initialization uses the
658 * BN_FLG_CONSTTIME flag
660 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
661 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
663 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
664 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
670 for (i = 0; i < ex_primes; i++) {
671 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
672 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
673 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
680 * We MUST free |factor| before any further use of the prime factors
684 smooth = (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
688 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
691 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
692 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
698 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
699 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
700 * to limb width. So that at the very least if |I| is fully reduced,
701 * i.e. less than p*q, we can count on from-to round to perform
702 * below modulo operations on |I|. Unlike BN_mod it's constant time.
704 if (/* m1 = I moq q */
705 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
706 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
707 /* m1 = m1^dmq1 mod q */
708 || !BN_mod_exp_mont_consttime(m1, m1, rsa->dmq1, rsa->q, ctx,
711 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
712 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
713 /* r1 = r1^dmp1 mod p */
714 || !BN_mod_exp_mont_consttime(r1, r1, rsa->dmp1, rsa->p, ctx,
716 /* r1 = (r1 - m1) mod p */
718 * bn_mod_sub_fixed_top is not regular modular subtraction,
719 * it can tolerate subtrahend to be larger than modulus, but
720 * not bit-wise wider. This makes up for uncommon q>p case,
721 * when |m1| can be larger than |rsa->p|.
723 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
725 /* r1 = r1 * iqmp mod p */
726 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
727 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
729 /* r0 = r1 * q + m1 */
730 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
731 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
737 /* compute I mod q */
739 BIGNUM *c = BN_new();
742 BN_with_flags(c, I, BN_FLG_CONSTTIME);
744 if (!BN_mod(r1, c, rsa->q, ctx)) {
750 BIGNUM *dmq1 = BN_new();
755 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
757 /* compute r1^dmq1 mod q */
758 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
759 rsa->_method_mod_q)) {
764 /* We MUST free dmq1 before any further use of rsa->dmq1 */
768 /* compute I mod p */
769 if (!BN_mod(r1, c, rsa->p, ctx)) {
773 /* We MUST free c before any further use of I */
778 BIGNUM *dmp1 = BN_new();
781 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
783 /* compute r1^dmp1 mod p */
784 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
785 rsa->_method_mod_p)) {
789 /* We MUST free dmp1 before any further use of rsa->dmp1 */
795 * calculate m_i in multi-prime case
798 * 1. squash the following two loops and calculate |m_i| there.
799 * 2. remove cc and reuse |c|.
800 * 3. remove |dmq1| and |dmp1| in previous block and use |di|.
802 * If these things are done, the code will be more readable.
805 BIGNUM *di = BN_new(), *cc = BN_new();
807 if (cc == NULL || di == NULL) {
813 for (i = 0; i < ex_primes; i++) {
815 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
821 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
823 /* prepare c and d_i */
824 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
825 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
827 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
832 /* compute r1 ^ d_i mod r_i */
833 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
845 if (!BN_sub(r0, r0, m1))
848 * This will help stop the size of r0 increasing, which does affect the
849 * multiply if it optimised for a power of 2 size
851 if (BN_is_negative(r0))
852 if (!BN_add(r0, r0, rsa->p))
855 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
859 BIGNUM *pr1 = BN_new();
862 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
864 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
868 /* We MUST free pr1 before any further use of r1 */
873 * If p < q it is occasionally possible for the correction of adding 'p'
874 * if r0 is negative above to leave the result still negative. This can
875 * break the private key operations: the following second correction
876 * should *always* correct this rare occurrence. This will *never* happen
877 * with OpenSSL generated keys because they ensure p > q [steve]
879 if (BN_is_negative(r0))
880 if (!BN_add(r0, r0, rsa->p))
882 if (!BN_mul(r1, r0, rsa->q, ctx))
884 if (!BN_add(r0, r1, m1))
888 /* add m_i to m in multi-prime case */
890 BIGNUM *pr2 = BN_new();
895 for (i = 0; i < ex_primes; i++) {
896 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
897 if (!BN_sub(r1, m[i], r0)) {
902 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
907 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
909 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
914 if (BN_is_negative(r1))
915 if (!BN_add(r1, r1, pinfo->r)) {
919 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
923 if (!BN_add(r0, r0, r1)) {
933 if (rsa->e && rsa->n) {
934 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
935 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
940 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
945 * If 'I' was greater than (or equal to) rsa->n, the operation will
946 * be equivalent to using 'I mod n'. However, the result of the
947 * verify will *always* be less than 'n' so we don't check for
948 * absolute equality, just congruency.
950 if (!BN_sub(vrfy, vrfy, I))
952 if (BN_is_zero(vrfy)) {
955 goto err; /* not actually error */
957 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
959 if (BN_is_negative(vrfy))
960 if (!BN_add(vrfy, vrfy, rsa->n))
962 if (!BN_is_zero(vrfy)) {
964 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
965 * miscalculated CRT output, just do a raw (slower) mod_exp and
966 * return that instead.
969 BIGNUM *d = BN_new();
972 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
974 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
975 rsa->_method_mod_n)) {
979 /* We MUST free d before any further use of rsa->d */
984 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
985 * saves the day is that correction is highly unlike, and private key
986 * operations are customarily performed on blinded message. Which means
987 * that attacker won't observe correlation with chosen plaintext.
988 * Secondly, remaining code would still handle it in same computational
989 * time and even conceal memory access pattern around corrected top.
998 static int rsa_ossl_init(RSA *rsa)
1000 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
1004 static int rsa_ossl_finish(RSA *rsa)
1008 RSA_PRIME_INFO *pinfo;
1010 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
1011 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
1012 BN_MONT_CTX_free(pinfo->m);
1016 BN_MONT_CTX_free(rsa->_method_mod_n);
1017 BN_MONT_CTX_free(rsa->_method_mod_p);
1018 BN_MONT_CTX_free(rsa->_method_mod_q);