2 * Copyright 1995-2023 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"
20 #include <openssl/evp.h>
21 #include <openssl/sha.h>
22 #include <openssl/hmac.h>
24 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
25 unsigned char *to, RSA *rsa, int padding);
26 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
27 unsigned char *to, RSA *rsa, int padding);
28 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
29 unsigned char *to, RSA *rsa, int padding);
30 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
31 unsigned char *to, RSA *rsa, int padding);
32 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
34 static int rsa_ossl_init(RSA *rsa);
35 static int rsa_ossl_finish(RSA *rsa);
37 static int rsa_ossl_s390x_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
39 static RSA_METHOD rsa_pkcs1_ossl_meth = {
41 rsa_ossl_public_encrypt,
42 rsa_ossl_public_decrypt, /* signature verification */
43 rsa_ossl_private_encrypt, /* signing */
44 rsa_ossl_private_decrypt,
45 rsa_ossl_s390x_mod_exp,
49 RSA_FLAG_FIPS_METHOD, /* flags */
53 NULL, /* rsa_keygen */
54 NULL /* rsa_multi_prime_keygen */
57 static RSA_METHOD rsa_pkcs1_ossl_meth = {
59 rsa_ossl_public_encrypt,
60 rsa_ossl_public_decrypt, /* signature verification */
61 rsa_ossl_private_encrypt, /* signing */
62 rsa_ossl_private_decrypt,
64 BN_mod_exp_mont, /* XXX probably we should not use Montgomery
68 RSA_FLAG_FIPS_METHOD, /* flags */
72 NULL, /* rsa_keygen */
73 NULL /* rsa_multi_prime_keygen */
77 static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth;
79 void RSA_set_default_method(const RSA_METHOD *meth)
81 default_RSA_meth = meth;
84 const RSA_METHOD *RSA_get_default_method(void)
86 return default_RSA_meth;
89 const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
91 return &rsa_pkcs1_ossl_meth;
94 const RSA_METHOD *RSA_null_method(void)
99 static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
100 unsigned char *to, RSA *rsa, int padding)
103 int i, num = 0, r = -1;
104 unsigned char *buf = NULL;
107 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
108 ERR_raise(ERR_LIB_RSA, RSA_R_MODULUS_TOO_LARGE);
112 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
113 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
117 /* for large moduli, enforce exponent limit */
118 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
119 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
120 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
125 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
129 ret = BN_CTX_get(ctx);
130 num = BN_num_bytes(rsa->n);
131 buf = OPENSSL_malloc(num);
132 if (ret == NULL || buf == NULL)
136 case RSA_PKCS1_PADDING:
137 i = ossl_rsa_padding_add_PKCS1_type_2_ex(rsa->libctx, buf, num,
140 case RSA_PKCS1_OAEP_PADDING:
141 i = ossl_rsa_padding_add_PKCS1_OAEP_mgf1_ex(rsa->libctx, buf, num,
146 i = RSA_padding_add_none(buf, num, from, flen);
149 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
155 if (BN_bin2bn(buf, num, f) == NULL)
158 if (BN_ucmp(f, rsa->n) >= 0) {
159 /* usually the padding functions would catch this */
160 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
164 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
165 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
169 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
174 * BN_bn2binpad puts in leading 0 bytes if the number is less than
175 * the length of the modulus.
177 r = BN_bn2binpad(ret, to, num);
181 OPENSSL_clear_free(buf, num);
185 static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
189 if (!CRYPTO_THREAD_read_lock(rsa->lock))
192 if (rsa->blinding == NULL) {
194 * This dance with upgrading the lock from read to write will be
195 * slower in cases of a single use RSA object, but should be
196 * significantly better in multi-thread cases (e.g. servers). It's
199 CRYPTO_THREAD_unlock(rsa->lock);
200 if (!CRYPTO_THREAD_write_lock(rsa->lock))
202 if (rsa->blinding == NULL)
203 rsa->blinding = RSA_setup_blinding(rsa, ctx);
210 if (BN_BLINDING_is_current_thread(ret)) {
211 /* rsa->blinding is ours! */
215 /* resort to rsa->mt_blinding instead */
218 * instructs rsa_blinding_convert(), rsa_blinding_invert() that the
219 * BN_BLINDING is shared, meaning that accesses require locks, and
220 * that the blinding factor must be stored outside the BN_BLINDING
224 if (rsa->mt_blinding == NULL) {
225 CRYPTO_THREAD_unlock(rsa->lock);
226 if (!CRYPTO_THREAD_write_lock(rsa->lock))
228 if (rsa->mt_blinding == NULL)
229 rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
231 ret = rsa->mt_blinding;
235 CRYPTO_THREAD_unlock(rsa->lock);
239 static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
242 if (unblind == NULL) {
244 * Local blinding: store the unblinding factor in BN_BLINDING.
246 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
249 * Shared blinding: store the unblinding factor outside BN_BLINDING.
253 if (!BN_BLINDING_lock(b))
256 ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
257 BN_BLINDING_unlock(b);
263 static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
267 * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
268 * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
269 * is shared between threads, unblind must be non-null:
270 * BN_BLINDING_invert_ex will then use the local unblinding factor, and
271 * will only read the modulus from BN_BLINDING. In both cases it's safe
272 * to access the blinding without a lock.
274 BN_set_flags(f, BN_FLG_CONSTTIME);
275 return BN_BLINDING_invert_ex(f, unblind, b, ctx);
279 static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
280 unsigned char *to, RSA *rsa, int padding)
282 BIGNUM *f, *ret, *res;
283 int i, num = 0, r = -1;
284 unsigned char *buf = NULL;
286 int local_blinding = 0;
288 * Used only if the blinding structure is shared. A non-NULL unblind
289 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
290 * the unblinding factor outside the blinding structure.
292 BIGNUM *unblind = NULL;
293 BN_BLINDING *blinding = NULL;
295 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
299 ret = BN_CTX_get(ctx);
300 num = BN_num_bytes(rsa->n);
301 buf = OPENSSL_malloc(num);
302 if (ret == NULL || buf == NULL)
306 case RSA_PKCS1_PADDING:
307 i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
309 case RSA_X931_PADDING:
310 i = RSA_padding_add_X931(buf, num, from, flen);
313 i = RSA_padding_add_none(buf, num, from, flen);
316 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
322 if (BN_bin2bn(buf, num, f) == NULL)
325 if (BN_ucmp(f, rsa->n) >= 0) {
326 /* usually the padding functions would catch this */
327 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
331 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
332 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
336 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
337 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
338 if (blinding == NULL) {
339 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
344 if (blinding != NULL) {
345 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
346 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
349 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
353 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
354 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
357 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
358 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
361 BIGNUM *d = BN_new();
363 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
366 if (rsa->d == NULL) {
367 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
371 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
373 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
374 rsa->_method_mod_n)) {
378 /* We MUST free d before any further use of rsa->d */
383 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
386 if (padding == RSA_X931_PADDING) {
387 if (!BN_sub(f, rsa->n, ret))
389 if (BN_cmp(ret, f) > 0)
398 * BN_bn2binpad puts in leading 0 bytes if the number is less than
399 * the length of the modulus.
401 r = BN_bn2binpad(res, to, num);
405 OPENSSL_clear_free(buf, num);
409 static int derive_kdk(int flen, const unsigned char *from, RSA *rsa,
410 unsigned char *buf, int num, unsigned char *kdk)
413 HMAC_CTX *hmac = NULL;
415 unsigned int md_len = SHA256_DIGEST_LENGTH;
416 unsigned char d_hash[SHA256_DIGEST_LENGTH] = {0};
418 * because we use d as a handle to rsa->d we need to keep it local and
419 * free before any further use of rsa->d
421 BIGNUM *d = BN_new();
424 ERR_raise(ERR_LIB_RSA, ERR_R_CRYPTO_LIB);
427 if (rsa->d == NULL) {
428 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
432 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
433 if (BN_bn2binpad(d, buf, num) < 0) {
434 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
441 * we use hardcoded hash so that migrating between versions that use
442 * different hash doesn't provide a Bleichenbacher oracle:
443 * if the attacker can see that different versions return different
444 * messages for the same ciphertext, they'll know that the message is
445 * synthetically generated, which means that the padding check failed
447 md = EVP_MD_fetch(rsa->libctx, "sha256", NULL);
449 ERR_raise(ERR_LIB_RSA, ERR_R_FETCH_FAILED);
453 if (EVP_Digest(buf, num, d_hash, NULL, md, NULL) <= 0) {
454 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
458 hmac = HMAC_CTX_new();
460 ERR_raise(ERR_LIB_RSA, ERR_R_CRYPTO_LIB);
464 if (HMAC_Init_ex(hmac, d_hash, sizeof(d_hash), md, NULL) <= 0) {
465 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
470 memset(buf, 0, num - flen);
471 if (HMAC_Update(hmac, buf, num - flen) <= 0) {
472 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
476 if (HMAC_Update(hmac, from, flen) <= 0) {
477 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
481 md_len = SHA256_DIGEST_LENGTH;
482 if (HMAC_Final(hmac, kdk, &md_len) <= 0) {
483 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
494 static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
495 unsigned char *to, RSA *rsa, int padding)
498 int j, num = 0, r = -1;
499 unsigned char *buf = NULL;
500 unsigned char kdk[SHA256_DIGEST_LENGTH] = {0};
502 int local_blinding = 0;
504 * Used only if the blinding structure is shared. A non-NULL unblind
505 * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
506 * the unblinding factor outside the blinding structure.
508 BIGNUM *unblind = NULL;
509 BN_BLINDING *blinding = NULL;
512 * we need the value of the private exponent to perform implicit rejection
514 if ((rsa->flags & RSA_FLAG_EXT_PKEY) && (padding == RSA_PKCS1_PADDING))
515 padding = RSA_PKCS1_NO_IMPLICIT_REJECT_PADDING;
517 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
521 ret = BN_CTX_get(ctx);
523 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
526 num = BN_num_bytes(rsa->n);
527 buf = OPENSSL_malloc(num);
532 * This check was for equality but PGP does evil things and chops off the
536 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_GREATER_THAN_MOD_LEN);
541 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_SMALL);
545 /* make data into a big number */
546 if (BN_bin2bn(from, (int)flen, f) == NULL)
549 if (BN_ucmp(f, rsa->n) >= 0) {
550 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
554 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
555 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
559 if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
560 blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
561 if (blinding == NULL) {
562 ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR);
567 if (blinding != NULL) {
568 if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
569 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
572 if (!rsa_blinding_convert(blinding, f, unblind, ctx))
577 if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
578 (rsa->version == RSA_ASN1_VERSION_MULTI) ||
581 (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
582 if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
585 BIGNUM *d = BN_new();
587 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
590 if (rsa->d == NULL) {
591 ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY);
595 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
596 if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
597 rsa->_method_mod_n)) {
601 /* We MUST free d before any further use of rsa->d */
606 if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
610 * derive the Key Derivation Key from private exponent and public
613 if (padding == RSA_PKCS1_PADDING) {
614 if (derive_kdk(flen, from, rsa, buf, num, kdk) == 0)
618 j = BN_bn2binpad(ret, buf, num);
623 case RSA_PKCS1_NO_IMPLICIT_REJECT_PADDING:
624 r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
626 case RSA_PKCS1_PADDING:
627 r = ossl_rsa_padding_check_PKCS1_type_2(rsa->libctx, to, num, buf, j, num, kdk);
629 case RSA_PKCS1_OAEP_PADDING:
630 r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
633 memcpy(to, buf, (r = j));
636 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
641 * This trick doesn't work in the FIPS provider because libcrypto manages
642 * the error stack. Instead we opt not to put an error on the stack at all
643 * in case of padding failure in the FIPS provider.
645 ERR_raise(ERR_LIB_RSA, RSA_R_PADDING_CHECK_FAILED);
646 err_clear_last_constant_time(1 & ~constant_time_msb(r));
652 OPENSSL_clear_free(buf, num);
656 /* signature verification */
657 static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
658 unsigned char *to, RSA *rsa, int padding)
661 int i, num = 0, r = -1;
662 unsigned char *buf = NULL;
665 if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
666 ERR_raise(ERR_LIB_RSA, RSA_R_MODULUS_TOO_LARGE);
670 if (BN_ucmp(rsa->n, rsa->e) <= 0) {
671 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
675 /* for large moduli, enforce exponent limit */
676 if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
677 if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
678 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
683 if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
687 ret = BN_CTX_get(ctx);
689 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
692 num = BN_num_bytes(rsa->n);
693 buf = OPENSSL_malloc(num);
698 * This check was for equality but PGP does evil things and chops off the
702 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_GREATER_THAN_MOD_LEN);
706 if (BN_bin2bn(from, flen, f) == NULL)
709 if (BN_ucmp(f, rsa->n) >= 0) {
710 ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
714 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
715 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
719 if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
723 if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
724 if (!BN_sub(ret, rsa->n, ret))
727 i = BN_bn2binpad(ret, buf, num);
732 case RSA_PKCS1_PADDING:
733 r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
735 case RSA_X931_PADDING:
736 r = RSA_padding_check_X931(to, num, buf, i, num);
739 memcpy(to, buf, (r = i));
742 ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE);
746 ERR_raise(ERR_LIB_RSA, RSA_R_PADDING_CHECK_FAILED);
751 OPENSSL_clear_free(buf, num);
755 static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
757 BIGNUM *r1, *m1, *vrfy;
758 int ret = 0, smooth = 0;
760 BIGNUM *r2, *m[RSA_MAX_PRIME_NUM - 2];
761 int i, ex_primes = 0;
762 RSA_PRIME_INFO *pinfo;
767 r1 = BN_CTX_get(ctx);
769 r2 = BN_CTX_get(ctx);
771 m1 = BN_CTX_get(ctx);
772 vrfy = BN_CTX_get(ctx);
777 if (rsa->version == RSA_ASN1_VERSION_MULTI
778 && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0
779 || ex_primes > RSA_MAX_PRIME_NUM - 2))
783 if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
784 BIGNUM *factor = BN_new();
790 * Make sure BN_mod_inverse in Montgomery initialization uses the
791 * BN_FLG_CONSTTIME flag
793 if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME),
794 BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock,
796 || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME),
797 BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock,
803 for (i = 0; i < ex_primes; i++) {
804 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
805 BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME);
806 if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) {
813 * We MUST free |factor| before any further use of the prime factors
817 smooth = (rsa->meth->bn_mod_exp == BN_mod_exp_mont)
821 && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p));
824 if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
825 if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock,
831 * Conversion from Montgomery domain, a.k.a. Montgomery reduction,
832 * accepts values in [0-m*2^w) range. w is m's bit width rounded up
833 * to limb width. So that at the very least if |I| is fully reduced,
834 * i.e. less than p*q, we can count on from-to round to perform
835 * below modulo operations on |I|. Unlike BN_mod it's constant time.
837 if (/* m1 = I moq q */
838 !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx)
839 || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx)
841 || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx)
842 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
844 * Use parallel exponentiations optimization if possible,
845 * otherwise fallback to two sequential exponentiations:
849 || !BN_mod_exp_mont_consttime_x2(m1, m1, rsa->dmq1, rsa->q,
851 r1, r1, rsa->dmp1, rsa->p,
854 /* r1 = (r1 - m1) mod p */
856 * bn_mod_sub_fixed_top is not regular modular subtraction,
857 * it can tolerate subtrahend to be larger than modulus, but
858 * not bit-wise wider. This makes up for uncommon q>p case,
859 * when |m1| can be larger than |rsa->p|.
861 || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p)
863 /* r1 = r1 * iqmp mod p */
864 || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx)
865 || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p,
867 /* r0 = r1 * q + m1 */
868 || !bn_mul_fixed_top(r0, r1, rsa->q, ctx)
869 || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n))
875 /* compute I mod q */
877 BIGNUM *c = BN_new();
880 BN_with_flags(c, I, BN_FLG_CONSTTIME);
882 if (!BN_mod(r1, c, rsa->q, ctx)) {
888 BIGNUM *dmq1 = BN_new();
893 BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
895 /* compute r1^dmq1 mod q */
896 if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
897 rsa->_method_mod_q)) {
902 /* We MUST free dmq1 before any further use of rsa->dmq1 */
906 /* compute I mod p */
907 if (!BN_mod(r1, c, rsa->p, ctx)) {
911 /* We MUST free c before any further use of I */
916 BIGNUM *dmp1 = BN_new();
919 BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
921 /* compute r1^dmp1 mod p */
922 if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
923 rsa->_method_mod_p)) {
927 /* We MUST free dmp1 before any further use of rsa->dmp1 */
933 BIGNUM *di = BN_new(), *cc = BN_new();
935 if (cc == NULL || di == NULL) {
941 for (i = 0; i < ex_primes; i++) {
943 if ((m[i] = BN_CTX_get(ctx)) == NULL) {
949 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
951 /* prepare c and d_i */
952 BN_with_flags(cc, I, BN_FLG_CONSTTIME);
953 BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME);
955 if (!BN_mod(r1, cc, pinfo->r, ctx)) {
960 /* compute r1 ^ d_i mod r_i */
961 if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) {
973 if (!BN_sub(r0, r0, m1))
976 * This will help stop the size of r0 increasing, which does affect the
977 * multiply if it optimised for a power of 2 size
979 if (BN_is_negative(r0))
980 if (!BN_add(r0, r0, rsa->p))
983 if (!BN_mul(r1, r0, rsa->iqmp, ctx))
987 BIGNUM *pr1 = BN_new();
990 BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
992 if (!BN_mod(r0, pr1, rsa->p, ctx)) {
996 /* We MUST free pr1 before any further use of r1 */
1001 * If p < q it is occasionally possible for the correction of adding 'p'
1002 * if r0 is negative above to leave the result still negative. This can
1003 * break the private key operations: the following second correction
1004 * should *always* correct this rare occurrence. This will *never* happen
1005 * with OpenSSL generated keys because they ensure p > q [steve]
1007 if (BN_is_negative(r0))
1008 if (!BN_add(r0, r0, rsa->p))
1010 if (!BN_mul(r1, r0, rsa->q, ctx))
1012 if (!BN_add(r0, r1, m1))
1016 /* add m_i to m in multi-prime case */
1017 if (ex_primes > 0) {
1018 BIGNUM *pr2 = BN_new();
1023 for (i = 0; i < ex_primes; i++) {
1024 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
1025 if (!BN_sub(r1, m[i], r0)) {
1030 if (!BN_mul(r2, r1, pinfo->t, ctx)) {
1035 BN_with_flags(pr2, r2, BN_FLG_CONSTTIME);
1037 if (!BN_mod(r1, pr2, pinfo->r, ctx)) {
1042 if (BN_is_negative(r1))
1043 if (!BN_add(r1, r1, pinfo->r)) {
1047 if (!BN_mul(r1, r1, pinfo->pp, ctx)) {
1051 if (!BN_add(r0, r0, r1)) {
1061 if (rsa->e && rsa->n) {
1062 if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) {
1063 if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx,
1064 rsa->_method_mod_n))
1068 if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
1069 rsa->_method_mod_n))
1073 * If 'I' was greater than (or equal to) rsa->n, the operation will
1074 * be equivalent to using 'I mod n'. However, the result of the
1075 * verify will *always* be less than 'n' so we don't check for
1076 * absolute equality, just congruency.
1078 if (!BN_sub(vrfy, vrfy, I))
1080 if (BN_is_zero(vrfy)) {
1083 goto err; /* not actually error */
1085 if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
1087 if (BN_is_negative(vrfy))
1088 if (!BN_add(vrfy, vrfy, rsa->n))
1090 if (!BN_is_zero(vrfy)) {
1092 * 'I' and 'vrfy' aren't congruent mod n. Don't leak
1093 * miscalculated CRT output, just do a raw (slower) mod_exp and
1094 * return that instead.
1097 BIGNUM *d = BN_new();
1100 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
1102 if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
1103 rsa->_method_mod_n)) {
1107 /* We MUST free d before any further use of rsa->d */
1112 * It's unfortunate that we have to bn_correct_top(r0). What hopefully
1113 * saves the day is that correction is highly unlike, and private key
1114 * operations are customarily performed on blinded message. Which means
1115 * that attacker won't observe correlation with chosen plaintext.
1116 * Secondly, remaining code would still handle it in same computational
1117 * time and even conceal memory access pattern around corrected top.
1126 static int rsa_ossl_init(RSA *rsa)
1128 rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
1132 static int rsa_ossl_finish(RSA *rsa)
1136 RSA_PRIME_INFO *pinfo;
1138 for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) {
1139 pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i);
1140 BN_MONT_CTX_free(pinfo->m);
1144 BN_MONT_CTX_free(rsa->_method_mod_n);
1145 BN_MONT_CTX_free(rsa->_method_mod_p);
1146 BN_MONT_CTX_free(rsa->_method_mod_q);
1150 #ifdef S390X_MOD_EXP
1151 static int rsa_ossl_s390x_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
1154 if (rsa->version != RSA_ASN1_VERSION_MULTI) {
1155 if (s390x_crt(r0, i, rsa->p, rsa->q, rsa->dmp1, rsa->dmq1, rsa->iqmp) == 1)
1158 return rsa_ossl_mod_exp(r0, i, rsa, ctx);