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 "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);
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);
358 OPENSSL_clear_free(buf, num);
362 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
363 unsigned char *to, RSA *rsa, int padding)
366 int j, num = 0, r = -1;
367 unsigned char *buf = NULL;
369 int local_blinding = 0;
371 * Used only if the blinding structure is shared. A non-NULL unblind
372 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
373 * the unblinding factor outside the blinding structure.
375 BIGNUM *unblind = NULL;
376 BN_BLINDING *blinding = NULL;
378 if ((ctx = BN_CTX_new()) == NULL)
382 ret = BN_CTX_get(ctx);
383 num = BN_num_bytes(rsa->n);
384 buf = OPENSSL_malloc(num);
385 if (ret == NULL || buf == NULL) {
386 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
391 * This check was for equality but PGP does evil things and chops off the
395 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
396 RSA_R_DATA_GREATER_THAN_MOD_LEN);
400 /* make data into a big number */
401 if (BN_bin2bn(from, (int)flen, f) == NULL)
404 if (BN_ucmp(f, rsa->n) >= 0) {
405 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
406 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
410 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
411 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
412 if (blinding == NULL) {
413 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
418 if (blinding != NULL) {
419 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
420 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
423 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
428 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
429 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
432 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
433 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
436 BIGNUM *d = BN_new();
438 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
441 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
443 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
444 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
449 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
450 rsa->_method_mod_n)) {
454 /* We MUST free d before any further use of rsa->d */
459 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
462 j = BN_bn2binpad(ret, buf, num);
465 case RSA_PKCS1_PADDING:
466 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
468 case RSA_PKCS1_OAEP_PADDING:
469 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
471 case RSA_SSLV23_PADDING:
472 r = RSA_padding_check_SSLv23(to, num, buf, j, num);
475 memcpy(to, buf, (r = j));
478 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
481 RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
482 err_clear_last_constant_time(1 & ~constant_time_msb(r));
487 OPENSSL_clear_free(buf, num);
491 /* signature verification */
492 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
493 unsigned char *to, RSA *rsa, int padding)
496 int i, num = 0, r = -1;
497 unsigned char *buf = NULL;
500 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
501 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
505 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
506 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
510 /* for large moduli, enforce exponent limit */
511 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
512 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
513 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
518 if ((ctx = BN_CTX_new()) == NULL)
522 ret = BN_CTX_get(ctx);
523 num = BN_num_bytes(rsa->n);
524 buf = OPENSSL_malloc(num);
525 if (ret == NULL || buf == NULL) {
526 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
531 * This check was for equality but PGP does evil things and chops off the
535 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
539 if (BN_bin2bn(from, flen, f) == NULL)
542 if (BN_ucmp(f, rsa->n) >= 0) {
543 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT,
544 RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
548 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
549 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
553 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
557 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
558 if (!BN_sub(ret, rsa->n, ret))
561 i = BN_bn2binpad(ret, buf, num);
564 case RSA_PKCS1_PADDING:
565 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
567 case RSA_X931_PADDING:
568 r = RSA_padding_check_X931(to, num, buf, i, num);
571 memcpy(to, buf, (r = i));
574 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
578 RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
583 OPENSSL_clear_free(buf, num);
587 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
589 BIGNUM *r1, *m1, *vrfy, *r2, *m[RSA_MAX_PRIME_NUM - 2];
590 int ret = 0, i, ex_primes = 0, smooth = 0;
591 RSA_PRIME_INFO *pinfo;
595 r1 = BN_CTX_get(ctx);
596 r2 = BN_CTX_get(ctx);
597 m1 = BN_CTX_get(ctx);
598 vrfy = BN_CTX_get(ctx);
602 if (rsa->version == RSA_ASN1_VERSION_MULTI
603 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
604 || ex_primes > RSA_MAX_PRIME_NUM - 2))
607 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
608 BIGNUM *factor = BN_new();
614 * Make sure BN_mod_inverse in Montgomery initialization uses the
615 * BN_FLG_CONSTTIME flag
617 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
618 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
620 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
621 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
626 for (i = 0; i < ex_primes; i++) {
627 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
628 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
629 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
635 * We MUST free |factor| before any further use of the prime factors
639 smooth = (ex_primes == 0)
640 && (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
641 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
644 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
645 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
651 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
652 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
653 * to limb width. So that at the very least if |I| is fully reduced,
654 * i.e. less than p*q, we can count on from-to round to perform
655 * below modulo operations on |I|. Unlike BN_mod it's constant time.
657 if (/* m1 = I moq q */
658 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
659 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
660 /* m1 = m1^dmq1 mod q */
661 || !BN_mod_exp_mont_consttime(m1, m1, rsa->dmq1, rsa->q, ctx,
664 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
665 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
666 /* r1 = r1^dmp1 mod p */
667 || !BN_mod_exp_mont_consttime(r1, r1, rsa->dmp1, rsa->p, ctx,
669 /* r1 = (r1 - m1) mod p */
671 * bn_mod_sub_fixed_top is not regular modular subtraction,
672 * it can tolerate subtrahend to be larger than modulus, but
673 * not bit-wise wider. This makes up for uncommon q>p case,
674 * when |m1| can be larger than |rsa->p|.
676 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
678 /* r1 = r1 * iqmp mod p */
679 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
680 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
682 /* r0 = r1 * q + m1 */
683 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
684 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
690 /* compute I mod q */
692 BIGNUM *c = BN_new();
695 BN_with_flags(c, I, BN_FLG_CONSTTIME);
697 if (!BN_mod(r1, c, rsa->q, ctx)) {
703 BIGNUM *dmq1 = BN_new();
708 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
710 /* compute r1^dmq1 mod q */
711 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
712 rsa->_method_mod_q)) {
717 /* We MUST free dmq1 before any further use of rsa->dmq1 */
721 /* compute I mod p */
722 if (!BN_mod(r1, c, rsa->p, ctx)) {
726 /* We MUST free c before any further use of I */
731 BIGNUM *dmp1 = BN_new();
734 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
736 /* compute r1^dmp1 mod p */
737 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
738 rsa->_method_mod_p)) {
742 /* We MUST free dmp1 before any further use of rsa->dmp1 */
747 * calculate m_i in multi-prime case
750 * 1. squash the following two loops and calculate |m_i| there.
751 * 2. remove cc and reuse |c|.
752 * 3. remove |dmq1| and |dmp1| in previous block and use |di|.
754 * If these things are done, the code will be more readable.
757 BIGNUM *di = BN_new(), *cc = BN_new();
759 if (cc == NULL || di == NULL) {
765 for (i = 0; i < ex_primes; i++) {
767 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
773 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
775 /* prepare c and d_i */
776 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
777 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
779 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
784 /* compute r1 ^ d_i mod r_i */
785 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
796 if (!BN_sub(r0, r0, m1))
799 * This will help stop the size of r0 increasing, which does affect the
800 * multiply if it optimised for a power of 2 size
802 if (BN_is_negative(r0))
803 if (!BN_add(r0, r0, rsa->p))
806 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
810 BIGNUM *pr1 = BN_new();
813 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
815 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
819 /* We MUST free pr1 before any further use of r1 */
824 * If p < q it is occasionally possible for the correction of adding 'p'
825 * if r0 is negative above to leave the result still negative. This can
826 * break the private key operations: the following second correction
827 * should *always* correct this rare occurrence. This will *never* happen
828 * with OpenSSL generated keys because they ensure p > q [steve]
830 if (BN_is_negative(r0))
831 if (!BN_add(r0, r0, rsa->p))
833 if (!BN_mul(r1, r0, rsa->q, ctx))
835 if (!BN_add(r0, r1, m1))
838 /* add m_i to m in multi-prime case */
840 BIGNUM *pr2 = BN_new();
845 for (i = 0; i < ex_primes; i++) {
846 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
847 if (!BN_sub(r1, m[i], r0)) {
852 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
857 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
859 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
864 if (BN_is_negative(r1))
865 if (!BN_add(r1, r1, pinfo->r)) {
869 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
873 if (!BN_add(r0, r0, r1)) {
882 if (rsa->e && rsa->n) {
883 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
884 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
889 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
894 * If 'I' was greater than (or equal to) rsa->n, the operation will
895 * be equivalent to using 'I mod n'. However, the result of the
896 * verify will *always* be less than 'n' so we don't check for
897 * absolute equality, just congruency.
899 if (!BN_sub(vrfy, vrfy, I))
901 if (BN_is_zero(vrfy)) {
904 goto err; /* not actually error */
906 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
908 if (BN_is_negative(vrfy))
909 if (!BN_add(vrfy, vrfy, rsa->n))
911 if (!BN_is_zero(vrfy)) {
913 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
914 * miscalculated CRT output, just do a raw (slower) mod_exp and
915 * return that instead.
918 BIGNUM *d = BN_new();
921 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
923 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
924 rsa->_method_mod_n)) {
928 /* We MUST free d before any further use of rsa->d */
933 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
934 * saves the day is that correction is highly unlike, and private key
935 * operations are customarily performed on blinded message. Which means
936 * that attacker won't observe correlation with chosen plaintext.
937 * Secondly, remaining code would still handle it in same computational
938 * time and even conceal memory access pattern around corrected top.
947 static int rsa_ossl_init(RSA *rsa)
949 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
953 static int rsa_ossl_finish(RSA *rsa)
956 RSA_PRIME_INFO *pinfo;
958 BN_MONT_CTX_free(rsa->_method_mod_n);
959 BN_MONT_CTX_free(rsa->_method_mod_p);
960 BN_MONT_CTX_free(rsa->_method_mod_q);
961 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
962 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
963 BN_MONT_CTX_free(pinfo->m);