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"
13 #include "internal/constant_time_locl.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);
154 OPENSSL_clear_free(buf, num);
158 static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
162 CRYPTO_THREAD_write_lock(rsa->lock);
164 if (rsa->blinding == NULL) {
165 rsa->blinding = RSA_setup_blinding(rsa, ctx);
172 if (BN_BLINDING_is_current_thread(ret)) {
173 /* rsa->blinding is ours! */
177 /* resort to rsa->mt_blinding instead */
180 * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
181 * BN_BLINDING is shared, meaning that accesses require locks, and
182 * that the blinding factor must be stored outside the BN_BLINDING
186 if (rsa->mt_blinding == NULL) {
187 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
189 ret = rsa->mt_blinding;
193 CRYPTO_THREAD_unlock(rsa->lock);
197 static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
200 if (unblind == NULL) {
202 * Local blinding: store the unblinding factor in BN_BLINDING.
204 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
207 * Shared blinding: store the unblinding factor outside BN_BLINDING.
212 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
213 BN_BLINDING_unlock(b);
219 static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
223 * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
224 * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
225 * is shared between threads, unblind must be non-null:
226 * BN_BLINDING_invert_ex will then use the local unblinding factor, and
227 * will only read the modulus from BN_BLINDING. In both cases it's safe
228 * to access the blinding without a lock.
230 return BN_BLINDING_invert_ex(f, unblind, b, ctx);
234 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
235 unsigned char *to, RSA *rsa, int padding)
237 BIGNUM *f, *ret, *res;
238 int i, num = 0, r = -1;
239 unsigned char *buf = NULL;
241 int local_blinding = 0;
243 * Used only if the blinding structure is shared. A non-NULL unblind
244 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
245 * the unblinding factor outside the blinding structure.
247 BIGNUM *unblind = NULL;
248 BN_BLINDING *blinding = NULL;
250 if ((ctx = BN_CTX_new()) == NULL)
254 ret = BN_CTX_get(ctx);
255 num = BN_num_bytes(rsa->n);
256 buf = OPENSSL_malloc(num);
257 if (ret == NULL || buf == NULL) {
258 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
263 case RSA_PKCS1_PADDING:
264 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
266 case RSA_X931_PADDING:
267 i = RSA_padding_add_X931(buf, num, from, flen);
270 i = RSA_padding_add_none(buf, num, from, flen);
272 case RSA_SSLV23_PADDING:
274 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
280 if (BN_bin2bn(buf, num, f) == NULL)
283 if (BN_ucmp(f, rsa->n) >= 0) {
284 /* usually the padding functions would catch this */
285 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT,
286 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
290 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
291 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
295 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
296 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
297 if (blinding == NULL) {
298 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
303 if (blinding != NULL) {
304 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
305 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
308 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
312 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
313 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
316 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
317 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
320 BIGNUM *d = BN_new();
322 RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
325 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
327 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
328 rsa->_method_mod_n)) {
332 /* We MUST free d before any further use of rsa->d */
337 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
340 if (padding == RSA_X931_PADDING) {
341 if (!BN_sub(f, rsa->n, ret))
343 if (BN_cmp(ret, f) > 0)
352 * BN_bn2binpad puts in leading 0 bytes if the number is less than
353 * the length of the modulus.
355 r = BN_bn2binpad(res, to, num);
360 OPENSSL_clear_free(buf, num);
364 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
365 unsigned char *to, RSA *rsa, int padding)
368 int j, num = 0, r = -1;
369 unsigned char *buf = NULL;
371 int local_blinding = 0;
373 * Used only if the blinding structure is shared. A non-NULL unblind
374 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
375 * the unblinding factor outside the blinding structure.
377 BIGNUM *unblind = NULL;
378 BN_BLINDING *blinding = NULL;
380 if ((ctx = BN_CTX_new()) == NULL)
384 ret = BN_CTX_get(ctx);
385 num = BN_num_bytes(rsa->n);
386 buf = OPENSSL_malloc(num);
387 if (ret == NULL || buf == NULL) {
388 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
393 * This check was for equality but PGP does evil things and chops off the
397 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
398 RSA_R_DATA_GREATER_THAN_MOD_LEN);
402 /* make data into a big number */
403 if (BN_bin2bn(from, (int)flen, f) == NULL)
406 if (BN_ucmp(f, rsa->n) >= 0) {
407 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
408 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
412 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
413 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
414 if (blinding == NULL) {
415 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
420 if (blinding != NULL) {
421 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
422 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
425 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
430 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
431 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
434 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
435 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
438 BIGNUM *d = BN_new();
440 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
443 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
445 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
446 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
451 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
452 rsa->_method_mod_n)) {
456 /* We MUST free d before any further use of rsa->d */
461 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
464 j = BN_bn2binpad(ret, buf, num);
467 case RSA_PKCS1_PADDING:
468 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
470 case RSA_PKCS1_OAEP_PADDING:
471 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
473 case RSA_SSLV23_PADDING:
474 r = RSA_padding_check_SSLv23(to, num, buf, j, num);
477 memcpy(to, buf, (r = j));
480 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);
484 err_clear_last_constant_time(r >= 0);
490 OPENSSL_clear_free(buf, num);
494 /* signature verification */
495 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
496 unsigned char *to, RSA *rsa, int padding)
499 int i, num = 0, r = -1;
500 unsigned char *buf = NULL;
503 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
504 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
508 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
509 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
513 /* for large moduli, enforce exponent limit */
514 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
515 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
516 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
521 if ((ctx = BN_CTX_new()) == NULL)
525 ret = BN_CTX_get(ctx);
526 num = BN_num_bytes(rsa->n);
527 buf = OPENSSL_malloc(num);
528 if (ret == NULL || buf == NULL) {
529 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
534 * This check was for equality but PGP does evil things and chops off the
538 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
542 if (BN_bin2bn(from, flen, f) == NULL)
545 if (BN_ucmp(f, rsa->n) >= 0) {
546 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT,
547 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
551 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
552 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
556 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
560 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
561 if (!BN_sub(ret, rsa->n, ret))
564 i = BN_bn2binpad(ret, buf, num);
567 case RSA_PKCS1_PADDING:
568 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
570 case RSA_X931_PADDING:
571 r = RSA_padding_check_X931(to, num, buf, i, num);
574 memcpy(to, buf, (r = i));
577 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
581 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
587 OPENSSL_clear_free(buf, num);
591 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
593 BIGNUM *r1, *m1, *vrfy, *r2, *m[RSA_MAX_PRIME_NUM - 2];
594 int ret = 0, i, ex_primes = 0, smooth = 0;
595 RSA_PRIME_INFO *pinfo;
599 r1 = BN_CTX_get(ctx);
600 r2 = BN_CTX_get(ctx);
601 m1 = BN_CTX_get(ctx);
602 vrfy = BN_CTX_get(ctx);
606 if (rsa->version == RSA_ASN1_VERSION_MULTI
607 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
608 || ex_primes > RSA_MAX_PRIME_NUM - 2))
611 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
612 BIGNUM *factor = BN_new();
618 * Make sure BN_mod_inverse in Montgomery initialization uses the
619 * BN_FLG_CONSTTIME flag
621 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
622 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
624 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
625 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
630 for (i = 0; i < ex_primes; i++) {
631 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
632 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
633 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
639 * We MUST free |factor| before any further use of the prime factors
643 smooth = (ex_primes == 0)
644 && (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
645 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
648 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
649 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
655 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
656 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
657 * to limb width. So that at the very least if |I| is fully reduced,
658 * i.e. less than p*q, we can count on from-to round to perform
659 * below modulo operations on |I|. Unlike BN_mod it's constant time.
661 if (/* m1 = I moq q */
662 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
663 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
664 /* m1 = m1^dmq1 mod q */
665 || !BN_mod_exp_mont_consttime(m1, m1, rsa->dmq1, rsa->q, ctx,
668 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
669 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
670 /* r1 = r1^dmp1 mod p */
671 || !BN_mod_exp_mont_consttime(r1, r1, rsa->dmp1, rsa->p, ctx,
673 /* r1 = (r1 - m1) mod p */
675 * bn_mod_sub_fixed_top is not regular modular subtraction,
676 * it can tolerate subtrahend to be larger than modulus, but
677 * not bit-wise wider. This makes up for uncommon q>p case,
678 * when |m1| can be larger than |rsa->p|.
680 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
682 /* r1 = r1 * iqmp mod p */
683 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
684 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
686 /* r0 = r1 * q + m1 */
687 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
688 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
694 /* compute I mod q */
696 BIGNUM *c = BN_new();
699 BN_with_flags(c, I, BN_FLG_CONSTTIME);
701 if (!BN_mod(r1, c, rsa->q, ctx)) {
707 BIGNUM *dmq1 = BN_new();
712 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
714 /* compute r1^dmq1 mod q */
715 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
716 rsa->_method_mod_q)) {
721 /* We MUST free dmq1 before any further use of rsa->dmq1 */
725 /* compute I mod p */
726 if (!BN_mod(r1, c, rsa->p, ctx)) {
730 /* We MUST free c before any further use of I */
735 BIGNUM *dmp1 = BN_new();
738 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
740 /* compute r1^dmp1 mod p */
741 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
742 rsa->_method_mod_p)) {
746 /* We MUST free dmp1 before any further use of rsa->dmp1 */
751 * calculate m_i in multi-prime case
754 * 1. squash the following two loops and calculate |m_i| there.
755 * 2. remove cc and reuse |c|.
756 * 3. remove |dmq1| and |dmp1| in previous block and use |di|.
758 * If these things are done, the code will be more readable.
761 BIGNUM *di = BN_new(), *cc = BN_new();
763 if (cc == NULL || di == NULL) {
769 for (i = 0; i < ex_primes; i++) {
771 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
777 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
779 /* prepare c and d_i */
780 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
781 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
783 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
788 /* compute r1 ^ d_i mod r_i */
789 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
800 if (!BN_sub(r0, r0, m1))
803 * This will help stop the size of r0 increasing, which does affect the
804 * multiply if it optimised for a power of 2 size
806 if (BN_is_negative(r0))
807 if (!BN_add(r0, r0, rsa->p))
810 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
814 BIGNUM *pr1 = BN_new();
817 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
819 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
823 /* We MUST free pr1 before any further use of r1 */
828 * If p < q it is occasionally possible for the correction of adding 'p'
829 * if r0 is negative above to leave the result still negative. This can
830 * break the private key operations: the following second correction
831 * should *always* correct this rare occurrence. This will *never* happen
832 * with OpenSSL generated keys because they ensure p > q [steve]
834 if (BN_is_negative(r0))
835 if (!BN_add(r0, r0, rsa->p))
837 if (!BN_mul(r1, r0, rsa->q, ctx))
839 if (!BN_add(r0, r1, m1))
842 /* add m_i to m in multi-prime case */
844 BIGNUM *pr2 = BN_new();
849 for (i = 0; i < ex_primes; i++) {
850 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
851 if (!BN_sub(r1, m[i], r0)) {
856 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
861 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
863 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
868 if (BN_is_negative(r1))
869 if (!BN_add(r1, r1, pinfo->r)) {
873 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
877 if (!BN_add(r0, r0, r1)) {
886 if (rsa->e && rsa->n) {
887 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
888 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
893 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
898 * If 'I' was greater than (or equal to) rsa->n, the operation will
899 * be equivalent to using 'I mod n'. However, the result of the
900 * verify will *always* be less than 'n' so we don't check for
901 * absolute equality, just congruency.
903 if (!BN_sub(vrfy, vrfy, I))
905 if (BN_is_zero(vrfy)) {
908 goto err; /* not actually error */
910 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
912 if (BN_is_negative(vrfy))
913 if (!BN_add(vrfy, vrfy, rsa->n))
915 if (!BN_is_zero(vrfy)) {
917 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
918 * miscalculated CRT output, just do a raw (slower) mod_exp and
919 * return that instead.
922 BIGNUM *d = BN_new();
925 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
927 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
928 rsa->_method_mod_n)) {
932 /* We MUST free d before any further use of rsa->d */
937 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
938 * saves the day is that correction is highly unlike, and private key
939 * operations are customarily performed on blinded message. Which means
940 * that attacker won't observe correlation with chosen plaintext.
941 * Secondly, remaining code would still handle it in same computational
942 * time and even conceal memory access pattern around corrected top.
951 static int rsa_ossl_init(RSA *rsa)
953 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
957 static int rsa_ossl_finish(RSA *rsa)
960 RSA_PRIME_INFO *pinfo;
962 BN_MONT_CTX_free(rsa->_method_mod_n);
963 BN_MONT_CTX_free(rsa->_method_mod_p);
964 BN_MONT_CTX_free(rsa->_method_mod_q);
965 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
966 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
967 BN_MONT_CTX_free(pinfo->m);