| /* |
| * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved. |
| * |
| * Licensed under the Apache License 2.0 (the "License"). You may not use |
| * this file except in compliance with the License. You can obtain a copy |
| * in the file LICENSE in the source distribution or at |
| * https://www.openssl.org/source/license.html |
| */ |
| |
| /* |
| * RSA low level APIs are deprecated for public use, but still ok for |
| * internal use. |
| */ |
| #include "internal/deprecated.h" |
| |
| #include "internal/cryptlib.h" |
| #include "crypto/bn.h" |
| #include "rsa_local.h" |
| #include "internal/constant_time.h" |
| |
| static int rsa_ossl_public_encrypt(int flen, const unsigned char *from, |
| unsigned char *to, RSA *rsa, int padding); |
| static int rsa_ossl_private_encrypt(int flen, const unsigned char *from, |
| unsigned char *to, RSA *rsa, int padding); |
| static int rsa_ossl_public_decrypt(int flen, const unsigned char *from, |
| unsigned char *to, RSA *rsa, int padding); |
| static int rsa_ossl_private_decrypt(int flen, const unsigned char *from, |
| unsigned char *to, RSA *rsa, int padding); |
| static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa, |
| BN_CTX *ctx); |
| static int rsa_ossl_init(RSA *rsa); |
| static int rsa_ossl_finish(RSA *rsa); |
| static RSA_METHOD rsa_pkcs1_ossl_meth = { |
| "OpenSSL PKCS#1 RSA", |
| rsa_ossl_public_encrypt, |
| rsa_ossl_public_decrypt, /* signature verification */ |
| rsa_ossl_private_encrypt, /* signing */ |
| rsa_ossl_private_decrypt, |
| rsa_ossl_mod_exp, |
| BN_mod_exp_mont, /* XXX probably we should not use Montgomery |
| * if e == 3 */ |
| rsa_ossl_init, |
| rsa_ossl_finish, |
| RSA_FLAG_FIPS_METHOD, /* flags */ |
| NULL, |
| 0, /* rsa_sign */ |
| 0, /* rsa_verify */ |
| NULL, /* rsa_keygen */ |
| NULL /* rsa_multi_prime_keygen */ |
| }; |
| |
| static const RSA_METHOD *default_RSA_meth = &rsa_pkcs1_ossl_meth; |
| |
| void RSA_set_default_method(const RSA_METHOD *meth) |
| { |
| default_RSA_meth = meth; |
| } |
| |
| const RSA_METHOD *RSA_get_default_method(void) |
| { |
| return default_RSA_meth; |
| } |
| |
| const RSA_METHOD *RSA_PKCS1_OpenSSL(void) |
| { |
| return &rsa_pkcs1_ossl_meth; |
| } |
| |
| const RSA_METHOD *RSA_null_method(void) |
| { |
| return NULL; |
| } |
| |
| static int rsa_ossl_public_encrypt(int flen, const unsigned char *from, |
| unsigned char *to, RSA *rsa, int padding) |
| { |
| BIGNUM *f, *ret; |
| int i, num = 0, r = -1; |
| unsigned char *buf = NULL; |
| BN_CTX *ctx = NULL; |
| |
| if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_MODULUS_TOO_LARGE); |
| return -1; |
| } |
| |
| if (BN_ucmp(rsa->n, rsa->e) <= 0) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE); |
| return -1; |
| } |
| |
| /* for large moduli, enforce exponent limit */ |
| if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) { |
| if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE); |
| return -1; |
| } |
| } |
| |
| if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL) |
| goto err; |
| BN_CTX_start(ctx); |
| f = BN_CTX_get(ctx); |
| ret = BN_CTX_get(ctx); |
| num = BN_num_bytes(rsa->n); |
| buf = OPENSSL_malloc(num); |
| if (ret == NULL || buf == NULL) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| switch (padding) { |
| case RSA_PKCS1_PADDING: |
| i = ossl_rsa_padding_add_PKCS1_type_2_ex(rsa->libctx, buf, num, |
| from, flen); |
| break; |
| case RSA_PKCS1_OAEP_PADDING: |
| i = ossl_rsa_padding_add_PKCS1_OAEP_mgf1_ex(rsa->libctx, buf, num, |
| from, flen, NULL, 0, |
| NULL, NULL); |
| break; |
| case RSA_NO_PADDING: |
| i = RSA_padding_add_none(buf, num, from, flen); |
| break; |
| default: |
| ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE); |
| goto err; |
| } |
| if (i <= 0) |
| goto err; |
| |
| if (BN_bin2bn(buf, num, f) == NULL) |
| goto err; |
| |
| if (BN_ucmp(f, rsa->n) >= 0) { |
| /* usually the padding functions would catch this */ |
| ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS); |
| goto err; |
| } |
| |
| if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) |
| if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock, |
| rsa->n, ctx)) |
| goto err; |
| |
| if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx, |
| rsa->_method_mod_n)) |
| goto err; |
| |
| /* |
| * BN_bn2binpad puts in leading 0 bytes if the number is less than |
| * the length of the modulus. |
| */ |
| r = BN_bn2binpad(ret, to, num); |
| err: |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| OPENSSL_clear_free(buf, num); |
| return r; |
| } |
| |
| static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx) |
| { |
| BN_BLINDING *ret; |
| |
| if (!CRYPTO_THREAD_write_lock(rsa->lock)) |
| return NULL; |
| |
| if (rsa->blinding == NULL) { |
| rsa->blinding = RSA_setup_blinding(rsa, ctx); |
| } |
| |
| ret = rsa->blinding; |
| if (ret == NULL) |
| goto err; |
| |
| if (BN_BLINDING_is_current_thread(ret)) { |
| /* rsa->blinding is ours! */ |
| |
| *local = 1; |
| } else { |
| /* resort to rsa->mt_blinding instead */ |
| |
| /* |
| * instructs rsa_blinding_convert(), rsa_blinding_invert() that the |
| * BN_BLINDING is shared, meaning that accesses require locks, and |
| * that the blinding factor must be stored outside the BN_BLINDING |
| */ |
| *local = 0; |
| |
| if (rsa->mt_blinding == NULL) { |
| rsa->mt_blinding = RSA_setup_blinding(rsa, ctx); |
| } |
| ret = rsa->mt_blinding; |
| } |
| |
| err: |
| CRYPTO_THREAD_unlock(rsa->lock); |
| return ret; |
| } |
| |
| static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind, |
| BN_CTX *ctx) |
| { |
| if (unblind == NULL) { |
| /* |
| * Local blinding: store the unblinding factor in BN_BLINDING. |
| */ |
| return BN_BLINDING_convert_ex(f, NULL, b, ctx); |
| } else { |
| /* |
| * Shared blinding: store the unblinding factor outside BN_BLINDING. |
| */ |
| int ret; |
| |
| if (!BN_BLINDING_lock(b)) |
| return 0; |
| |
| ret = BN_BLINDING_convert_ex(f, unblind, b, ctx); |
| BN_BLINDING_unlock(b); |
| |
| return ret; |
| } |
| } |
| |
| static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind, |
| BN_CTX *ctx) |
| { |
| /* |
| * For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex |
| * will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING |
| * is shared between threads, unblind must be non-null: |
| * BN_BLINDING_invert_ex will then use the local unblinding factor, and |
| * will only read the modulus from BN_BLINDING. In both cases it's safe |
| * to access the blinding without a lock. |
| */ |
| return BN_BLINDING_invert_ex(f, unblind, b, ctx); |
| } |
| |
| /* signing */ |
| static int rsa_ossl_private_encrypt(int flen, const unsigned char *from, |
| unsigned char *to, RSA *rsa, int padding) |
| { |
| BIGNUM *f, *ret, *res; |
| int i, num = 0, r = -1; |
| unsigned char *buf = NULL; |
| BN_CTX *ctx = NULL; |
| int local_blinding = 0; |
| /* |
| * Used only if the blinding structure is shared. A non-NULL unblind |
| * instructs rsa_blinding_convert() and rsa_blinding_invert() to store |
| * the unblinding factor outside the blinding structure. |
| */ |
| BIGNUM *unblind = NULL; |
| BN_BLINDING *blinding = NULL; |
| |
| if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL) |
| goto err; |
| BN_CTX_start(ctx); |
| f = BN_CTX_get(ctx); |
| ret = BN_CTX_get(ctx); |
| num = BN_num_bytes(rsa->n); |
| buf = OPENSSL_malloc(num); |
| if (ret == NULL || buf == NULL) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| switch (padding) { |
| case RSA_PKCS1_PADDING: |
| i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen); |
| break; |
| case RSA_X931_PADDING: |
| i = RSA_padding_add_X931(buf, num, from, flen); |
| break; |
| case RSA_NO_PADDING: |
| i = RSA_padding_add_none(buf, num, from, flen); |
| break; |
| default: |
| ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE); |
| goto err; |
| } |
| if (i <= 0) |
| goto err; |
| |
| if (BN_bin2bn(buf, num, f) == NULL) |
| goto err; |
| |
| if (BN_ucmp(f, rsa->n) >= 0) { |
| /* usually the padding functions would catch this */ |
| ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS); |
| goto err; |
| } |
| |
| if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) |
| if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock, |
| rsa->n, ctx)) |
| goto err; |
| |
| if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) { |
| blinding = rsa_get_blinding(rsa, &local_blinding, ctx); |
| if (blinding == NULL) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR); |
| goto err; |
| } |
| } |
| |
| if (blinding != NULL) { |
| if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| if (!rsa_blinding_convert(blinding, f, unblind, ctx)) |
| goto err; |
| } |
| |
| if ((rsa->flags & RSA_FLAG_EXT_PKEY) || |
| (rsa->version == RSA_ASN1_VERSION_MULTI) || |
| ((rsa->p != NULL) && |
| (rsa->q != NULL) && |
| (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) { |
| if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx)) |
| goto err; |
| } else { |
| BIGNUM *d = BN_new(); |
| if (d == NULL) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| if (rsa->d == NULL) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY); |
| BN_free(d); |
| goto err; |
| } |
| BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME); |
| |
| if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx, |
| rsa->_method_mod_n)) { |
| BN_free(d); |
| goto err; |
| } |
| /* We MUST free d before any further use of rsa->d */ |
| BN_free(d); |
| } |
| |
| if (blinding) |
| if (!rsa_blinding_invert(blinding, ret, unblind, ctx)) |
| goto err; |
| |
| if (padding == RSA_X931_PADDING) { |
| if (!BN_sub(f, rsa->n, ret)) |
| goto err; |
| if (BN_cmp(ret, f) > 0) |
| res = f; |
| else |
| res = ret; |
| } else { |
| res = ret; |
| } |
| |
| /* |
| * BN_bn2binpad puts in leading 0 bytes if the number is less than |
| * the length of the modulus. |
| */ |
| r = BN_bn2binpad(res, to, num); |
| err: |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| OPENSSL_clear_free(buf, num); |
| return r; |
| } |
| |
| static int rsa_ossl_private_decrypt(int flen, const unsigned char *from, |
| unsigned char *to, RSA *rsa, int padding) |
| { |
| BIGNUM *f, *ret; |
| int j, num = 0, r = -1; |
| unsigned char *buf = NULL; |
| BN_CTX *ctx = NULL; |
| int local_blinding = 0; |
| /* |
| * Used only if the blinding structure is shared. A non-NULL unblind |
| * instructs rsa_blinding_convert() and rsa_blinding_invert() to store |
| * the unblinding factor outside the blinding structure. |
| */ |
| BIGNUM *unblind = NULL; |
| BN_BLINDING *blinding = NULL; |
| |
| if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL) |
| goto err; |
| BN_CTX_start(ctx); |
| f = BN_CTX_get(ctx); |
| ret = BN_CTX_get(ctx); |
| num = BN_num_bytes(rsa->n); |
| buf = OPENSSL_malloc(num); |
| if (ret == NULL || buf == NULL) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| /* |
| * This check was for equality but PGP does evil things and chops off the |
| * top '0' bytes |
| */ |
| if (flen > num) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_DATA_GREATER_THAN_MOD_LEN); |
| goto err; |
| } |
| |
| /* make data into a big number */ |
| if (BN_bin2bn(from, (int)flen, f) == NULL) |
| goto err; |
| |
| if (BN_ucmp(f, rsa->n) >= 0) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS); |
| goto err; |
| } |
| |
| if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) { |
| blinding = rsa_get_blinding(rsa, &local_blinding, ctx); |
| if (blinding == NULL) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_INTERNAL_ERROR); |
| goto err; |
| } |
| } |
| |
| if (blinding != NULL) { |
| if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| if (!rsa_blinding_convert(blinding, f, unblind, ctx)) |
| goto err; |
| } |
| |
| /* do the decrypt */ |
| if ((rsa->flags & RSA_FLAG_EXT_PKEY) || |
| (rsa->version == RSA_ASN1_VERSION_MULTI) || |
| ((rsa->p != NULL) && |
| (rsa->q != NULL) && |
| (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) { |
| if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx)) |
| goto err; |
| } else { |
| BIGNUM *d = BN_new(); |
| if (d == NULL) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| if (rsa->d == NULL) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_MISSING_PRIVATE_KEY); |
| BN_free(d); |
| goto err; |
| } |
| BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME); |
| |
| if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) |
| if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock, |
| rsa->n, ctx)) { |
| BN_free(d); |
| goto err; |
| } |
| if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx, |
| rsa->_method_mod_n)) { |
| BN_free(d); |
| goto err; |
| } |
| /* We MUST free d before any further use of rsa->d */ |
| BN_free(d); |
| } |
| |
| if (blinding) |
| if (!rsa_blinding_invert(blinding, ret, unblind, ctx)) |
| goto err; |
| |
| j = BN_bn2binpad(ret, buf, num); |
| if (j < 0) |
| goto err; |
| |
| switch (padding) { |
| case RSA_PKCS1_PADDING: |
| r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num); |
| break; |
| case RSA_PKCS1_OAEP_PADDING: |
| r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0); |
| break; |
| case RSA_NO_PADDING: |
| memcpy(to, buf, (r = j)); |
| break; |
| default: |
| ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE); |
| goto err; |
| } |
| #ifndef FIPS_MODULE |
| /* |
| * This trick doesn't work in the FIPS provider because libcrypto manages |
| * the error stack. Instead we opt not to put an error on the stack at all |
| * in case of padding failure in the FIPS provider. |
| */ |
| ERR_raise(ERR_LIB_RSA, RSA_R_PADDING_CHECK_FAILED); |
| err_clear_last_constant_time(1 & ~constant_time_msb(r)); |
| #endif |
| |
| err: |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| OPENSSL_clear_free(buf, num); |
| return r; |
| } |
| |
| /* signature verification */ |
| static int rsa_ossl_public_decrypt(int flen, const unsigned char *from, |
| unsigned char *to, RSA *rsa, int padding) |
| { |
| BIGNUM *f, *ret; |
| int i, num = 0, r = -1; |
| unsigned char *buf = NULL; |
| BN_CTX *ctx = NULL; |
| |
| if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_MODULUS_TOO_LARGE); |
| return -1; |
| } |
| |
| if (BN_ucmp(rsa->n, rsa->e) <= 0) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE); |
| return -1; |
| } |
| |
| /* for large moduli, enforce exponent limit */ |
| if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) { |
| if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE); |
| return -1; |
| } |
| } |
| |
| if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL) |
| goto err; |
| BN_CTX_start(ctx); |
| f = BN_CTX_get(ctx); |
| ret = BN_CTX_get(ctx); |
| num = BN_num_bytes(rsa->n); |
| buf = OPENSSL_malloc(num); |
| if (ret == NULL || buf == NULL) { |
| ERR_raise(ERR_LIB_RSA, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| /* |
| * This check was for equality but PGP does evil things and chops off the |
| * top '0' bytes |
| */ |
| if (flen > num) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_DATA_GREATER_THAN_MOD_LEN); |
| goto err; |
| } |
| |
| if (BN_bin2bn(from, flen, f) == NULL) |
| goto err; |
| |
| if (BN_ucmp(f, rsa->n) >= 0) { |
| ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS); |
| goto err; |
| } |
| |
| if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) |
| if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock, |
| rsa->n, ctx)) |
| goto err; |
| |
| if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx, |
| rsa->_method_mod_n)) |
| goto err; |
| |
| if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12)) |
| if (!BN_sub(ret, rsa->n, ret)) |
| goto err; |
| |
| i = BN_bn2binpad(ret, buf, num); |
| if (i < 0) |
| goto err; |
| |
| switch (padding) { |
| case RSA_PKCS1_PADDING: |
| r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num); |
| break; |
| case RSA_X931_PADDING: |
| r = RSA_padding_check_X931(to, num, buf, i, num); |
| break; |
| case RSA_NO_PADDING: |
| memcpy(to, buf, (r = i)); |
| break; |
| default: |
| ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_PADDING_TYPE); |
| goto err; |
| } |
| if (r < 0) |
| ERR_raise(ERR_LIB_RSA, RSA_R_PADDING_CHECK_FAILED); |
| |
| err: |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| OPENSSL_clear_free(buf, num); |
| return r; |
| } |
| |
| static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) |
| { |
| BIGNUM *r1, *m1, *vrfy; |
| int ret = 0, smooth = 0; |
| #ifndef FIPS_MODULE |
| BIGNUM *r2, *m[RSA_MAX_PRIME_NUM - 2]; |
| int i, ex_primes = 0; |
| RSA_PRIME_INFO *pinfo; |
| #endif |
| |
| BN_CTX_start(ctx); |
| |
| r1 = BN_CTX_get(ctx); |
| #ifndef FIPS_MODULE |
| r2 = BN_CTX_get(ctx); |
| #endif |
| m1 = BN_CTX_get(ctx); |
| vrfy = BN_CTX_get(ctx); |
| if (vrfy == NULL) |
| goto err; |
| |
| #ifndef FIPS_MODULE |
| if (rsa->version == RSA_ASN1_VERSION_MULTI |
| && ((ex_primes = sk_RSA_PRIME_INFO_num(rsa->prime_infos)) <= 0 |
| || ex_primes > RSA_MAX_PRIME_NUM - 2)) |
| goto err; |
| #endif |
| |
| if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) { |
| BIGNUM *factor = BN_new(); |
| |
| if (factor == NULL) |
| goto err; |
| |
| /* |
| * Make sure BN_mod_inverse in Montgomery initialization uses the |
| * BN_FLG_CONSTTIME flag |
| */ |
| if (!(BN_with_flags(factor, rsa->p, BN_FLG_CONSTTIME), |
| BN_MONT_CTX_set_locked(&rsa->_method_mod_p, rsa->lock, |
| factor, ctx)) |
| || !(BN_with_flags(factor, rsa->q, BN_FLG_CONSTTIME), |
| BN_MONT_CTX_set_locked(&rsa->_method_mod_q, rsa->lock, |
| factor, ctx))) { |
| BN_free(factor); |
| goto err; |
| } |
| #ifndef FIPS_MODULE |
| for (i = 0; i < ex_primes; i++) { |
| pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i); |
| BN_with_flags(factor, pinfo->r, BN_FLG_CONSTTIME); |
| if (!BN_MONT_CTX_set_locked(&pinfo->m, rsa->lock, factor, ctx)) { |
| BN_free(factor); |
| goto err; |
| } |
| } |
| #endif |
| /* |
| * We MUST free |factor| before any further use of the prime factors |
| */ |
| BN_free(factor); |
| |
| smooth = (rsa->meth->bn_mod_exp == BN_mod_exp_mont) |
| #ifndef FIPS_MODULE |
| && (ex_primes == 0) |
| #endif |
| && (BN_num_bits(rsa->q) == BN_num_bits(rsa->p)); |
| } |
| |
| if (rsa->flags & RSA_FLAG_CACHE_PUBLIC) |
| if (!BN_MONT_CTX_set_locked(&rsa->_method_mod_n, rsa->lock, |
| rsa->n, ctx)) |
| goto err; |
| |
| if (smooth) { |
| /* |
| * Conversion from Montgomery domain, a.k.a. Montgomery reduction, |
| * accepts values in [0-m*2^w) range. w is m's bit width rounded up |
| * to limb width. So that at the very least if |I| is fully reduced, |
| * i.e. less than p*q, we can count on from-to round to perform |
| * below modulo operations on |I|. Unlike BN_mod it's constant time. |
| */ |
| if (/* m1 = I moq q */ |
| !bn_from_mont_fixed_top(m1, I, rsa->_method_mod_q, ctx) |
| || !bn_to_mont_fixed_top(m1, m1, rsa->_method_mod_q, ctx) |
| /* r1 = I mod p */ |
| || !bn_from_mont_fixed_top(r1, I, rsa->_method_mod_p, ctx) |
| || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx) |
| /* |
| * Use parallel exponentiations optimization if possible, |
| * otherwise fallback to two sequential exponentiations: |
| * m1 = m1^dmq1 mod q |
| * r1 = r1^dmp1 mod p |
| */ |
| || !BN_mod_exp_mont_consttime_x2(m1, m1, rsa->dmq1, rsa->q, |
| rsa->_method_mod_q, |
| r1, r1, rsa->dmp1, rsa->p, |
| rsa->_method_mod_p, |
| ctx) |
| /* r1 = (r1 - m1) mod p */ |
| /* |
| * bn_mod_sub_fixed_top is not regular modular subtraction, |
| * it can tolerate subtrahend to be larger than modulus, but |
| * not bit-wise wider. This makes up for uncommon q>p case, |
| * when |m1| can be larger than |rsa->p|. |
| */ |
| || !bn_mod_sub_fixed_top(r1, r1, m1, rsa->p) |
| |
| /* r1 = r1 * iqmp mod p */ |
| || !bn_to_mont_fixed_top(r1, r1, rsa->_method_mod_p, ctx) |
| || !bn_mul_mont_fixed_top(r1, r1, rsa->iqmp, rsa->_method_mod_p, |
| ctx) |
| /* r0 = r1 * q + m1 */ |
| || !bn_mul_fixed_top(r0, r1, rsa->q, ctx) |
| || !bn_mod_add_fixed_top(r0, r0, m1, rsa->n)) |
| goto err; |
| |
| goto tail; |
| } |
| |
| /* compute I mod q */ |
| { |
| BIGNUM *c = BN_new(); |
| if (c == NULL) |
| goto err; |
| BN_with_flags(c, I, BN_FLG_CONSTTIME); |
| |
| if (!BN_mod(r1, c, rsa->q, ctx)) { |
| BN_free(c); |
| goto err; |
| } |
| |
| { |
| BIGNUM *dmq1 = BN_new(); |
| if (dmq1 == NULL) { |
| BN_free(c); |
| goto err; |
| } |
| BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME); |
| |
| /* compute r1^dmq1 mod q */ |
| if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx, |
| rsa->_method_mod_q)) { |
| BN_free(c); |
| BN_free(dmq1); |
| goto err; |
| } |
| /* We MUST free dmq1 before any further use of rsa->dmq1 */ |
| BN_free(dmq1); |
| } |
| |
| /* compute I mod p */ |
| if (!BN_mod(r1, c, rsa->p, ctx)) { |
| BN_free(c); |
| goto err; |
| } |
| /* We MUST free c before any further use of I */ |
| BN_free(c); |
| } |
| |
| { |
| BIGNUM *dmp1 = BN_new(); |
| if (dmp1 == NULL) |
| goto err; |
| BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME); |
| |
| /* compute r1^dmp1 mod p */ |
| if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx, |
| rsa->_method_mod_p)) { |
| BN_free(dmp1); |
| goto err; |
| } |
| /* We MUST free dmp1 before any further use of rsa->dmp1 */ |
| BN_free(dmp1); |
| } |
| |
| #ifndef FIPS_MODULE |
| if (ex_primes > 0) { |
| BIGNUM *di = BN_new(), *cc = BN_new(); |
| |
| if (cc == NULL || di == NULL) { |
| BN_free(cc); |
| BN_free(di); |
| goto err; |
| } |
| |
| for (i = 0; i < ex_primes; i++) { |
| /* prepare m_i */ |
| if ((m[i] = BN_CTX_get(ctx)) == NULL) { |
| BN_free(cc); |
| BN_free(di); |
| goto err; |
| } |
| |
| pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i); |
| |
| /* prepare c and d_i */ |
| BN_with_flags(cc, I, BN_FLG_CONSTTIME); |
| BN_with_flags(di, pinfo->d, BN_FLG_CONSTTIME); |
| |
| if (!BN_mod(r1, cc, pinfo->r, ctx)) { |
| BN_free(cc); |
| BN_free(di); |
| goto err; |
| } |
| /* compute r1 ^ d_i mod r_i */ |
| if (!rsa->meth->bn_mod_exp(m[i], r1, di, pinfo->r, ctx, pinfo->m)) { |
| BN_free(cc); |
| BN_free(di); |
| goto err; |
| } |
| } |
| |
| BN_free(cc); |
| BN_free(di); |
| } |
| #endif |
| |
| if (!BN_sub(r0, r0, m1)) |
| goto err; |
| /* |
| * This will help stop the size of r0 increasing, which does affect the |
| * multiply if it optimised for a power of 2 size |
| */ |
| if (BN_is_negative(r0)) |
| if (!BN_add(r0, r0, rsa->p)) |
| goto err; |
| |
| if (!BN_mul(r1, r0, rsa->iqmp, ctx)) |
| goto err; |
| |
| { |
| BIGNUM *pr1 = BN_new(); |
| if (pr1 == NULL) |
| goto err; |
| BN_with_flags(pr1, r1, BN_FLG_CONSTTIME); |
| |
| if (!BN_mod(r0, pr1, rsa->p, ctx)) { |
| BN_free(pr1); |
| goto err; |
| } |
| /* We MUST free pr1 before any further use of r1 */ |
| BN_free(pr1); |
| } |
| |
| /* |
| * If p < q it is occasionally possible for the correction of adding 'p' |
| * if r0 is negative above to leave the result still negative. This can |
| * break the private key operations: the following second correction |
| * should *always* correct this rare occurrence. This will *never* happen |
| * with OpenSSL generated keys because they ensure p > q [steve] |
| */ |
| if (BN_is_negative(r0)) |
| if (!BN_add(r0, r0, rsa->p)) |
| goto err; |
| if (!BN_mul(r1, r0, rsa->q, ctx)) |
| goto err; |
| if (!BN_add(r0, r1, m1)) |
| goto err; |
| |
| #ifndef FIPS_MODULE |
| /* add m_i to m in multi-prime case */ |
| if (ex_primes > 0) { |
| BIGNUM *pr2 = BN_new(); |
| |
| if (pr2 == NULL) |
| goto err; |
| |
| for (i = 0; i < ex_primes; i++) { |
| pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i); |
| if (!BN_sub(r1, m[i], r0)) { |
| BN_free(pr2); |
| goto err; |
| } |
| |
| if (!BN_mul(r2, r1, pinfo->t, ctx)) { |
| BN_free(pr2); |
| goto err; |
| } |
| |
| BN_with_flags(pr2, r2, BN_FLG_CONSTTIME); |
| |
| if (!BN_mod(r1, pr2, pinfo->r, ctx)) { |
| BN_free(pr2); |
| goto err; |
| } |
| |
| if (BN_is_negative(r1)) |
| if (!BN_add(r1, r1, pinfo->r)) { |
| BN_free(pr2); |
| goto err; |
| } |
| if (!BN_mul(r1, r1, pinfo->pp, ctx)) { |
| BN_free(pr2); |
| goto err; |
| } |
| if (!BN_add(r0, r0, r1)) { |
| BN_free(pr2); |
| goto err; |
| } |
| } |
| BN_free(pr2); |
| } |
| #endif |
| |
| tail: |
| if (rsa->e && rsa->n) { |
| if (rsa->meth->bn_mod_exp == BN_mod_exp_mont) { |
| if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx, |
| rsa->_method_mod_n)) |
| goto err; |
| } else { |
| bn_correct_top(r0); |
| if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx, |
| rsa->_method_mod_n)) |
| goto err; |
| } |
| /* |
| * If 'I' was greater than (or equal to) rsa->n, the operation will |
| * be equivalent to using 'I mod n'. However, the result of the |
| * verify will *always* be less than 'n' so we don't check for |
| * absolute equality, just congruency. |
| */ |
| if (!BN_sub(vrfy, vrfy, I)) |
| goto err; |
| if (BN_is_zero(vrfy)) { |
| bn_correct_top(r0); |
| ret = 1; |
| goto err; /* not actually error */ |
| } |
| if (!BN_mod(vrfy, vrfy, rsa->n, ctx)) |
| goto err; |
| if (BN_is_negative(vrfy)) |
| if (!BN_add(vrfy, vrfy, rsa->n)) |
| goto err; |
| if (!BN_is_zero(vrfy)) { |
| /* |
| * 'I' and 'vrfy' aren't congruent mod n. Don't leak |
| * miscalculated CRT output, just do a raw (slower) mod_exp and |
| * return that instead. |
| */ |
| |
| BIGNUM *d = BN_new(); |
| if (d == NULL) |
| goto err; |
| BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME); |
| |
| if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx, |
| rsa->_method_mod_n)) { |
| BN_free(d); |
| goto err; |
| } |
| /* We MUST free d before any further use of rsa->d */ |
| BN_free(d); |
| } |
| } |
| /* |
| * It's unfortunate that we have to bn_correct_top(r0). What hopefully |
| * saves the day is that correction is highly unlike, and private key |
| * operations are customarily performed on blinded message. Which means |
| * that attacker won't observe correlation with chosen plaintext. |
| * Secondly, remaining code would still handle it in same computational |
| * time and even conceal memory access pattern around corrected top. |
| */ |
| bn_correct_top(r0); |
| ret = 1; |
| err: |
| BN_CTX_end(ctx); |
| return ret; |
| } |
| |
| static int rsa_ossl_init(RSA *rsa) |
| { |
| rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE; |
| return 1; |
| } |
| |
| static int rsa_ossl_finish(RSA *rsa) |
| { |
| #ifndef FIPS_MODULE |
| int i; |
| RSA_PRIME_INFO *pinfo; |
| |
| for (i = 0; i < sk_RSA_PRIME_INFO_num(rsa->prime_infos); i++) { |
| pinfo = sk_RSA_PRIME_INFO_value(rsa->prime_infos, i); |
| BN_MONT_CTX_free(pinfo->m); |
| } |
| #endif |
| |
| BN_MONT_CTX_free(rsa->_method_mod_n); |
| BN_MONT_CTX_free(rsa->_method_mod_p); |
| BN_MONT_CTX_free(rsa->_method_mod_q); |
| return 1; |
| } |
