/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */ #include #include #include #include #include #include #include #include #include #include "internal.h" #include "../bn/internal.h" #include "../../internal.h" #include "../delocate.h" static int check_modulus_and_exponent_sizes(const RSA *rsa) { unsigned rsa_bits = BN_num_bits(rsa->n); if (rsa_bits > 16 * 1024) { OPENSSL_PUT_ERROR(RSA, RSA_R_MODULUS_TOO_LARGE); return 0; } /* Mitigate DoS attacks by limiting the exponent size. 33 bits was chosen as * the limit based on the recommendations in [1] and [2]. Windows CryptoAPI * doesn't support values larger than 32 bits [3], so it is unlikely that * exponents larger than 32 bits are being used for anything Windows commonly * does. * * [1] https://www.imperialviolet.org/2012/03/16/rsae.html * [2] https://www.imperialviolet.org/2012/03/17/rsados.html * [3] https://msdn.microsoft.com/en-us/library/aa387685(VS.85).aspx */ static const unsigned kMaxExponentBits = 33; if (BN_num_bits(rsa->e) > kMaxExponentBits) { OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_E_VALUE); return 0; } /* Verify |n > e|. Comparing |rsa_bits| to |kMaxExponentBits| is a small * shortcut to comparing |n| and |e| directly. In reality, |kMaxExponentBits| * is much smaller than the minimum RSA key size that any application should * accept. */ if (rsa_bits <= kMaxExponentBits) { OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL); return 0; } assert(BN_ucmp(rsa->n, rsa->e) > 0); return 1; } size_t rsa_default_size(const RSA *rsa) { return BN_num_bytes(rsa->n); } int RSA_encrypt(RSA *rsa, size_t *out_len, uint8_t *out, size_t max_out, const uint8_t *in, size_t in_len, int padding) { if (rsa->n == NULL || rsa->e == NULL) { OPENSSL_PUT_ERROR(RSA, RSA_R_VALUE_MISSING); return 0; } const unsigned rsa_size = RSA_size(rsa); BIGNUM *f, *result; uint8_t *buf = NULL; BN_CTX *ctx = NULL; int i, ret = 0; if (max_out < rsa_size) { OPENSSL_PUT_ERROR(RSA, RSA_R_OUTPUT_BUFFER_TOO_SMALL); return 0; } if (!check_modulus_and_exponent_sizes(rsa)) { return 0; } ctx = BN_CTX_new(); if (ctx == NULL) { goto err; } BN_CTX_start(ctx); f = BN_CTX_get(ctx); result = BN_CTX_get(ctx); buf = OPENSSL_malloc(rsa_size); if (!f || !result || !buf) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } switch (padding) { case RSA_PKCS1_PADDING: i = RSA_padding_add_PKCS1_type_2(buf, rsa_size, in, in_len); break; case RSA_PKCS1_OAEP_PADDING: /* Use the default parameters: SHA-1 for both hashes and no label. */ i = RSA_padding_add_PKCS1_OAEP_mgf1(buf, rsa_size, in, in_len, NULL, 0, NULL, NULL); break; case RSA_NO_PADDING: i = RSA_padding_add_none(buf, rsa_size, in, in_len); break; default: OPENSSL_PUT_ERROR(RSA, RSA_R_UNKNOWN_PADDING_TYPE); goto err; } if (i <= 0) { goto err; } if (BN_bin2bn(buf, rsa_size, f) == NULL) { goto err; } if (BN_ucmp(f, rsa->n) >= 0) { /* usually the padding functions would catch this */ OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE); goto err; } if (!BN_MONT_CTX_set_locked(&rsa->mont_n, &rsa->lock, rsa->n, ctx) || !BN_mod_exp_mont(result, f, rsa->e, rsa->n, ctx, rsa->mont_n)) { goto err; } /* put in leading 0 bytes if the number is less than the length of the * modulus */ if (!BN_bn2bin_padded(out, rsa_size, result)) { OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); goto err; } *out_len = rsa_size; ret = 1; err: if (ctx != NULL) { BN_CTX_end(ctx); BN_CTX_free(ctx); } if (buf != NULL) { OPENSSL_cleanse(buf, rsa_size); OPENSSL_free(buf); } return ret; } /* MAX_BLINDINGS_PER_RSA defines the maximum number of cached BN_BLINDINGs per * RSA*. Then this limit is exceeded, BN_BLINDING objects will be created and * destroyed as needed. */ #define MAX_BLINDINGS_PER_RSA 1024 /* rsa_blinding_get returns a BN_BLINDING to use with |rsa|. It does this by * allocating one of the cached BN_BLINDING objects in |rsa->blindings|. If * none are free, the cache will be extended by a extra element and the new * BN_BLINDING is returned. * * On success, the index of the assigned BN_BLINDING is written to * |*index_used| and must be passed to |rsa_blinding_release| when finished. */ static BN_BLINDING *rsa_blinding_get(RSA *rsa, unsigned *index_used, BN_CTX *ctx) { assert(ctx != NULL); assert(rsa->mont_n != NULL); BN_BLINDING *ret = NULL; BN_BLINDING **new_blindings; uint8_t *new_blindings_inuse; char overflow = 0; CRYPTO_MUTEX_lock_write(&rsa->lock); unsigned i; for (i = 0; i < rsa->num_blindings; i++) { if (rsa->blindings_inuse[i] == 0) { rsa->blindings_inuse[i] = 1; ret = rsa->blindings[i]; *index_used = i; break; } } if (ret != NULL) { CRYPTO_MUTEX_unlock_write(&rsa->lock); return ret; } overflow = rsa->num_blindings >= MAX_BLINDINGS_PER_RSA; /* We didn't find a free BN_BLINDING to use so increase the length of * the arrays by one and use the newly created element. */ CRYPTO_MUTEX_unlock_write(&rsa->lock); ret = BN_BLINDING_new(); if (ret == NULL) { return NULL; } if (overflow) { /* We cannot add any more cached BN_BLINDINGs so we use |ret| * and mark it for destruction in |rsa_blinding_release|. */ *index_used = MAX_BLINDINGS_PER_RSA; return ret; } CRYPTO_MUTEX_lock_write(&rsa->lock); new_blindings = OPENSSL_malloc(sizeof(BN_BLINDING *) * (rsa->num_blindings + 1)); if (new_blindings == NULL) { goto err1; } OPENSSL_memcpy(new_blindings, rsa->blindings, sizeof(BN_BLINDING *) * rsa->num_blindings); new_blindings[rsa->num_blindings] = ret; new_blindings_inuse = OPENSSL_malloc(rsa->num_blindings + 1); if (new_blindings_inuse == NULL) { goto err2; } OPENSSL_memcpy(new_blindings_inuse, rsa->blindings_inuse, rsa->num_blindings); new_blindings_inuse[rsa->num_blindings] = 1; *index_used = rsa->num_blindings; OPENSSL_free(rsa->blindings); rsa->blindings = new_blindings; OPENSSL_free(rsa->blindings_inuse); rsa->blindings_inuse = new_blindings_inuse; rsa->num_blindings++; CRYPTO_MUTEX_unlock_write(&rsa->lock); return ret; err2: OPENSSL_free(new_blindings); err1: CRYPTO_MUTEX_unlock_write(&rsa->lock); BN_BLINDING_free(ret); return NULL; } /* rsa_blinding_release marks the cached BN_BLINDING at the given index as free * for other threads to use. */ static void rsa_blinding_release(RSA *rsa, BN_BLINDING *blinding, unsigned blinding_index) { if (blinding_index == MAX_BLINDINGS_PER_RSA) { /* This blinding wasn't cached. */ BN_BLINDING_free(blinding); return; } CRYPTO_MUTEX_lock_write(&rsa->lock); rsa->blindings_inuse[blinding_index] = 0; CRYPTO_MUTEX_unlock_write(&rsa->lock); } /* signing */ int rsa_default_sign_raw(RSA *rsa, size_t *out_len, uint8_t *out, size_t max_out, const uint8_t *in, size_t in_len, int padding) { const unsigned rsa_size = RSA_size(rsa); uint8_t *buf = NULL; int i, ret = 0; if (max_out < rsa_size) { OPENSSL_PUT_ERROR(RSA, RSA_R_OUTPUT_BUFFER_TOO_SMALL); return 0; } buf = OPENSSL_malloc(rsa_size); if (buf == NULL) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } switch (padding) { case RSA_PKCS1_PADDING: i = RSA_padding_add_PKCS1_type_1(buf, rsa_size, in, in_len); break; case RSA_NO_PADDING: i = RSA_padding_add_none(buf, rsa_size, in, in_len); break; default: OPENSSL_PUT_ERROR(RSA, RSA_R_UNKNOWN_PADDING_TYPE); goto err; } if (i <= 0) { goto err; } if (!RSA_private_transform(rsa, out, buf, rsa_size)) { goto err; } *out_len = rsa_size; ret = 1; err: if (buf != NULL) { OPENSSL_cleanse(buf, rsa_size); OPENSSL_free(buf); } return ret; } int rsa_default_decrypt(RSA *rsa, size_t *out_len, uint8_t *out, size_t max_out, const uint8_t *in, size_t in_len, int padding) { const unsigned rsa_size = RSA_size(rsa); uint8_t *buf = NULL; int ret = 0; if (max_out < rsa_size) { OPENSSL_PUT_ERROR(RSA, RSA_R_OUTPUT_BUFFER_TOO_SMALL); return 0; } if (padding == RSA_NO_PADDING) { buf = out; } else { /* Allocate a temporary buffer to hold the padded plaintext. */ buf = OPENSSL_malloc(rsa_size); if (buf == NULL) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } } if (in_len != rsa_size) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_LEN_NOT_EQUAL_TO_MOD_LEN); goto err; } if (!RSA_private_transform(rsa, buf, in, rsa_size)) { goto err; } switch (padding) { case RSA_PKCS1_PADDING: ret = RSA_padding_check_PKCS1_type_2(out, out_len, rsa_size, buf, rsa_size); break; case RSA_PKCS1_OAEP_PADDING: /* Use the default parameters: SHA-1 for both hashes and no label. */ ret = RSA_padding_check_PKCS1_OAEP_mgf1(out, out_len, rsa_size, buf, rsa_size, NULL, 0, NULL, NULL); break; case RSA_NO_PADDING: *out_len = rsa_size; ret = 1; break; default: OPENSSL_PUT_ERROR(RSA, RSA_R_UNKNOWN_PADDING_TYPE); goto err; } if (!ret) { OPENSSL_PUT_ERROR(RSA, RSA_R_PADDING_CHECK_FAILED); } err: if (padding != RSA_NO_PADDING && buf != NULL) { OPENSSL_cleanse(buf, rsa_size); OPENSSL_free(buf); } return ret; } static int mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx); int RSA_verify_raw(RSA *rsa, size_t *out_len, uint8_t *out, size_t max_out, const uint8_t *in, size_t in_len, int padding) { if (rsa->n == NULL || rsa->e == NULL) { OPENSSL_PUT_ERROR(RSA, RSA_R_VALUE_MISSING); return 0; } const unsigned rsa_size = RSA_size(rsa); BIGNUM *f, *result; if (max_out < rsa_size) { OPENSSL_PUT_ERROR(RSA, RSA_R_OUTPUT_BUFFER_TOO_SMALL); return 0; } if (in_len != rsa_size) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_LEN_NOT_EQUAL_TO_MOD_LEN); return 0; } if (!check_modulus_and_exponent_sizes(rsa)) { return 0; } BN_CTX *ctx = BN_CTX_new(); if (ctx == NULL) { return 0; } int ret = 0; uint8_t *buf = NULL; BN_CTX_start(ctx); f = BN_CTX_get(ctx); result = BN_CTX_get(ctx); if (f == NULL || result == NULL) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } if (padding == RSA_NO_PADDING) { buf = out; } else { /* Allocate a temporary buffer to hold the padded plaintext. */ buf = OPENSSL_malloc(rsa_size); if (buf == NULL) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } } if (BN_bin2bn(in, in_len, f) == NULL) { goto err; } if (BN_ucmp(f, rsa->n) >= 0) { OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE); goto err; } if (!BN_MONT_CTX_set_locked(&rsa->mont_n, &rsa->lock, rsa->n, ctx) || !BN_mod_exp_mont(result, f, rsa->e, rsa->n, ctx, rsa->mont_n)) { goto err; } if (!BN_bn2bin_padded(buf, rsa_size, result)) { OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); goto err; } switch (padding) { case RSA_PKCS1_PADDING: ret = RSA_padding_check_PKCS1_type_1(out, out_len, rsa_size, buf, rsa_size); break; case RSA_NO_PADDING: ret = 1; *out_len = rsa_size; break; default: OPENSSL_PUT_ERROR(RSA, RSA_R_UNKNOWN_PADDING_TYPE); goto err; } if (!ret) { OPENSSL_PUT_ERROR(RSA, RSA_R_PADDING_CHECK_FAILED); goto err; } err: BN_CTX_end(ctx); BN_CTX_free(ctx); if (buf != out) { OPENSSL_free(buf); } return ret; } int rsa_default_private_transform(RSA *rsa, uint8_t *out, const uint8_t *in, size_t len) { if (rsa->n == NULL || rsa->d == NULL) { OPENSSL_PUT_ERROR(RSA, RSA_R_VALUE_MISSING); return 0; } BIGNUM *f, *result; BN_CTX *ctx = NULL; unsigned blinding_index = 0; BN_BLINDING *blinding = NULL; int ret = 0; ctx = BN_CTX_new(); if (ctx == NULL) { goto err; } BN_CTX_start(ctx); f = BN_CTX_get(ctx); result = BN_CTX_get(ctx); if (f == NULL || result == NULL) { OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE); goto err; } if (BN_bin2bn(in, len, f) == NULL) { goto err; } if (BN_ucmp(f, rsa->n) >= 0) { /* Usually the padding functions would catch this. */ OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE); goto err; } if (!BN_MONT_CTX_set_locked(&rsa->mont_n, &rsa->lock, rsa->n, ctx)) { OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); goto err; } const int do_blinding = (rsa->flags & RSA_FLAG_NO_BLINDING) == 0; if (rsa->e == NULL && do_blinding) { /* We cannot do blinding or verification without |e|, and continuing without * those countermeasures is dangerous. However, the Java/Android RSA API * requires support for keys where only |d| and |n| (and not |e|) are known. * The callers that require that bad behavior set |RSA_FLAG_NO_BLINDING|. */ OPENSSL_PUT_ERROR(RSA, RSA_R_NO_PUBLIC_EXPONENT); goto err; } if (do_blinding) { blinding = rsa_blinding_get(rsa, &blinding_index, ctx); if (blinding == NULL) { OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); goto err; } if (!BN_BLINDING_convert(f, blinding, rsa->e, rsa->mont_n, ctx)) { goto err; } } if (rsa->p != NULL && rsa->q != NULL && rsa->e != NULL && rsa->dmp1 != NULL && rsa->dmq1 != NULL && rsa->iqmp != NULL) { if (!mod_exp(result, f, rsa, ctx)) { goto err; } } else if (!BN_mod_exp_mont_consttime(result, f, rsa->d, rsa->n, ctx, rsa->mont_n)) { goto err; } /* Verify the result to protect against fault attacks as described in the * 1997 paper "On the Importance of Checking Cryptographic Protocols for * Faults" by Dan Boneh, Richard A. DeMillo, and Richard J. Lipton. Some * implementations do this only when the CRT is used, but we do it in all * cases. Section 6 of the aforementioned paper describes an attack that * works when the CRT isn't used. That attack is much less likely to succeed * than the CRT attack, but there have likely been improvements since 1997. * * This check is cheap assuming |e| is small; it almost always is. */ if (rsa->e != NULL) { BIGNUM *vrfy = BN_CTX_get(ctx); if (vrfy == NULL || !BN_mod_exp_mont(vrfy, result, rsa->e, rsa->n, ctx, rsa->mont_n) || !BN_equal_consttime(vrfy, f)) { OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); goto err; } } if (do_blinding && !BN_BLINDING_invert(result, blinding, rsa->mont_n, ctx)) { goto err; } if (!BN_bn2bin_padded(out, len, result)) { OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); goto err; } ret = 1; err: if (ctx != NULL) { BN_CTX_end(ctx); BN_CTX_free(ctx); } if (blinding != NULL) { rsa_blinding_release(rsa, blinding, blinding_index); } return ret; } static int mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) { assert(ctx != NULL); assert(rsa->n != NULL); assert(rsa->e != NULL); assert(rsa->d != NULL); assert(rsa->p != NULL); assert(rsa->q != NULL); assert(rsa->dmp1 != NULL); assert(rsa->dmq1 != NULL); assert(rsa->iqmp != NULL); BIGNUM *r1, *m1, *vrfy; int ret = 0; BN_CTX_start(ctx); r1 = BN_CTX_get(ctx); m1 = BN_CTX_get(ctx); vrfy = BN_CTX_get(ctx); if (r1 == NULL || m1 == NULL || vrfy == NULL) { goto err; } if (!BN_MONT_CTX_set_locked(&rsa->mont_p, &rsa->lock, rsa->p, ctx) || !BN_MONT_CTX_set_locked(&rsa->mont_q, &rsa->lock, rsa->q, ctx)) { goto err; } if (!BN_MONT_CTX_set_locked(&rsa->mont_n, &rsa->lock, rsa->n, ctx)) { goto err; } /* compute I mod q */ if (!BN_mod(r1, I, rsa->q, ctx)) { goto err; } /* compute r1^dmq1 mod q */ if (!BN_mod_exp_mont_consttime(m1, r1, rsa->dmq1, rsa->q, ctx, rsa->mont_q)) { goto err; } /* compute I mod p */ if (!BN_mod(r1, I, rsa->p, ctx)) { goto err; } /* compute r1^dmp1 mod p */ if (!BN_mod_exp_mont_consttime(r0, r1, rsa->dmp1, rsa->p, ctx, rsa->mont_p)) { goto err; } 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; } if (!BN_mod(r0, r1, rsa->p, ctx)) { goto err; } /* 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; } ret = 1; err: BN_CTX_end(ctx); return ret; } static int ensure_bignum(BIGNUM **out) { if (*out == NULL) { *out = BN_new(); } return *out != NULL; } /* kBoringSSLRSASqrtTwo is the BIGNUM representation of ⌊2¹⁵³⁵×√2⌋. This is * chosen to give enough precision for 3072-bit RSA, the largest key size FIPS * specifies. Key sizes beyond this will round up. * * To verify this number, check that n² < 2³⁰⁷¹ < (n+1)², where n is value * represented here. Note the components are listed in little-endian order. Here * is some sample Python code to check: * * >>> TOBN = lambda a, b: a << 32 | b * >>> l = [ ] * >>> n = sum(a * 2**(64*i) for i, a in enumerate(l)) * >>> n**2 < 2**3071 < (n+1)**2 * True */ const BN_ULONG kBoringSSLRSASqrtTwo[] = { TOBN(0xdea06241, 0xf7aa81c2), TOBN(0xf6a1be3f, 0xca221307), TOBN(0x332a5e9f, 0x7bda1ebf), TOBN(0x0104dc01, 0xfe32352f), TOBN(0xb8cf341b, 0x6f8236c7), TOBN(0x4264dabc, 0xd528b651), TOBN(0xf4d3a02c, 0xebc93e0c), TOBN(0x81394ab6, 0xd8fd0efd), TOBN(0xeaa4a089, 0x9040ca4a), TOBN(0xf52f120f, 0x836e582e), TOBN(0xcb2a6343, 0x31f3c84d), TOBN(0xc6d5a8a3, 0x8bb7e9dc), TOBN(0x460abc72, 0x2f7c4e33), TOBN(0xcab1bc91, 0x1688458a), TOBN(0x53059c60, 0x11bc337b), TOBN(0xd2202e87, 0x42af1f4e), TOBN(0x78048736, 0x3dfa2768), TOBN(0x0f74a85e, 0x439c7b4a), TOBN(0xa8b1fe6f, 0xdc83db39), TOBN(0x4afc8304, 0x3ab8a2c3), TOBN(0xed17ac85, 0x83339915), TOBN(0x1d6f60ba, 0x893ba84c), TOBN(0x597d89b3, 0x754abe9f), TOBN(0xb504f333, 0xf9de6484), }; const size_t kBoringSSLRSASqrtTwoLen = OPENSSL_ARRAY_SIZE(kBoringSSLRSASqrtTwo); int rsa_less_than_words(const BN_ULONG *a, const BN_ULONG *b, size_t len) { OPENSSL_COMPILE_ASSERT(sizeof(BN_ULONG) <= sizeof(crypto_word_t), crypto_word_t_too_small); int ret = 0; /* Process the words in little-endian order. */ for (size_t i = 0; i < len; i++) { crypto_word_t eq = constant_time_eq_w(a[i], b[i]); crypto_word_t lt = constant_time_lt_w(a[i], b[i]); ret = constant_time_select_int(eq, ret, constant_time_select_int(lt, 1, 0)); } return ret; } int rsa_greater_than_pow2(const BIGNUM *b, int n) { if (BN_is_negative(b) || n == INT_MAX) { return 0; } int b_bits = BN_num_bits(b); return b_bits > n + 1 || (b_bits == n + 1 && !BN_is_pow2(b)); } /* generate_prime sets |out| to a prime with length |bits| such that |out|-1 is * relatively prime to |e|. If |p| is non-NULL, |out| will also not be close to * |p|. */ static int generate_prime(BIGNUM *out, int bits, const BIGNUM *e, const BIGNUM *p, BN_CTX *ctx, BN_GENCB *cb) { if (bits < 128 || (bits % BN_BITS2) != 0) { OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); return 0; } /* Ensure the bound on |tries| does not overflow. */ if (bits >= INT_MAX/5) { OPENSSL_PUT_ERROR(RSA, RSA_R_MODULUS_TOO_LARGE); return 0; } int ret = 0, tries = 0, rand_tries = 0; BN_CTX_start(ctx); BIGNUM *tmp = BN_CTX_get(ctx); if (tmp == NULL) { goto err; } /* See FIPS 186-4 appendix B.3.3, steps 4 and 5. Note |bits| here is * nlen/2. */ for (;;) { /* Generate a random number of length |bits| where the bottom bit is set * (steps 4.2, 4.3, 5.2 and 5.3) and the top bit is set (implied by the * bound checked below in steps 4.4 and 5.5). */ if (!BN_rand(out, bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD) || !BN_GENCB_call(cb, BN_GENCB_GENERATED, rand_tries++)) { goto err; } if (p != NULL) { /* If |p| and |out| are too close, try again (step 5.4). */ if (!BN_sub(tmp, out, p)) { goto err; } BN_set_negative(tmp, 0); if (!rsa_greater_than_pow2(tmp, bits - 100)) { continue; } } /* If out < 2^(bits-1)×√2, try again (steps 4.4 and 5.5). * * We check the most significant words, so we retry if ⌊out/2^k⌋ <= ⌊b/2^k⌋, * where b = 2^(bits-1)×√2 and k = max(0, bits - 1536). For key sizes up to * 3072 (bits = 1536), k = 0, so we are testing that ⌊out⌋ <= ⌊b⌋. out is an * integer and b is not, so this is equivalent to out < b. That is, the * comparison is exact for FIPS key sizes. * * For larger keys, the comparison is approximate, leaning towards * retrying. That is, we reject a negligible fraction of primes that are * within the FIPS bound, but we will never accept a prime outside the * bound, ensuring the resulting RSA key is the right size. Specifically, if * the FIPS bound holds, we have ⌊out/2^k⌋ < out/2^k < b/2^k. This implies * ⌊out/2^k⌋ <= ⌊b/2^k⌋. That is, the FIPS bound implies our bound and so we * are slightly tighter. */ size_t out_len = (size_t)out->top; assert(out_len == (size_t)bits / BN_BITS2); size_t to_check = kBoringSSLRSASqrtTwoLen; if (to_check > out_len) { to_check = out_len; } if (!rsa_less_than_words( kBoringSSLRSASqrtTwo + kBoringSSLRSASqrtTwoLen - to_check, out->d + out_len - to_check, to_check)) { continue; } /* Check gcd(out-1, e) is one (steps 4.5 and 5.6). */ if (!BN_sub(tmp, out, BN_value_one()) || !BN_gcd(tmp, tmp, e, ctx)) { goto err; } if (BN_is_one(tmp)) { /* Test |out| for primality (steps 4.5.1 and 5.6.1). */ int is_probable_prime; if (!BN_primality_test(&is_probable_prime, out, BN_prime_checks, ctx, 1, cb)) { goto err; } if (is_probable_prime) { ret = 1; goto err; } } /* If we've tried too many times to find a prime, abort (steps 4.7 and * 5.8). */ tries++; if (tries >= bits * 5) { OPENSSL_PUT_ERROR(RSA, RSA_R_TOO_MANY_ITERATIONS); goto err; } if (!BN_GENCB_call(cb, 2, tries)) { goto err; } } err: BN_CTX_end(ctx); return ret; } int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) { /* See FIPS 186-4 appendix B.3. This function implements a generalized version * of the FIPS algorithm. |RSA_generate_key_fips| performs additional checks * for FIPS-compliant key generation. */ /* Always generate RSA keys which are a multiple of 128 bits. Round |bits| * down as needed. */ bits &= ~127; /* Reject excessively small keys. */ if (bits < 256) { OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL); return 0; } int ret = 0; BN_CTX *ctx = BN_CTX_new(); if (ctx == NULL) { goto bn_err; } BN_CTX_start(ctx); BIGNUM *totient = BN_CTX_get(ctx); BIGNUM *pm1 = BN_CTX_get(ctx); BIGNUM *qm1 = BN_CTX_get(ctx); BIGNUM *gcd = BN_CTX_get(ctx); if (totient == NULL || pm1 == NULL || qm1 == NULL || gcd == NULL) { goto bn_err; } /* We need the RSA components non-NULL. */ if (!ensure_bignum(&rsa->n) || !ensure_bignum(&rsa->d) || !ensure_bignum(&rsa->e) || !ensure_bignum(&rsa->p) || !ensure_bignum(&rsa->q) || !ensure_bignum(&rsa->dmp1) || !ensure_bignum(&rsa->dmq1) || !ensure_bignum(&rsa->iqmp)) { goto bn_err; } if (!BN_copy(rsa->e, e_value)) { goto bn_err; } int prime_bits = bits / 2; do { /* Generate p and q, each of size |prime_bits|, using the steps outlined in * appendix FIPS 186-4 appendix B.3.3. */ if (!generate_prime(rsa->p, prime_bits, rsa->e, NULL, ctx, cb) || !BN_GENCB_call(cb, 3, 0) || !generate_prime(rsa->q, prime_bits, rsa->e, rsa->p, ctx, cb) || !BN_GENCB_call(cb, 3, 1)) { goto bn_err; } if (BN_cmp(rsa->p, rsa->q) < 0) { BIGNUM *tmp = rsa->p; rsa->p = rsa->q; rsa->q = tmp; } /* Calculate d = e^(-1) (mod lcm(p-1, q-1)), per FIPS 186-4. This differs * from typical RSA implementations which use (p-1)*(q-1). * * Note this means the size of d might reveal information about p-1 and * q-1. However, we do operations with Chinese Remainder Theorem, so we only * use d (mod p-1) and d (mod q-1) as exponents. Using a minimal totient * does not affect those two values. */ if (!BN_sub(pm1, rsa->p, BN_value_one()) || !BN_sub(qm1, rsa->q, BN_value_one()) || !BN_mul(totient, pm1, qm1, ctx) || !BN_gcd(gcd, pm1, qm1, ctx) || !BN_div(totient, NULL, totient, gcd, ctx) || !BN_mod_inverse(rsa->d, rsa->e, totient, ctx)) { goto bn_err; } /* Check that |rsa->d| > 2^|prime_bits| and try again if it fails. See * appendix B.3.1's guidance on values for d. */ } while (!rsa_greater_than_pow2(rsa->d, prime_bits)); if (/* Calculate n. */ !BN_mul(rsa->n, rsa->p, rsa->q, ctx) || /* Calculate d mod (p-1). */ !BN_mod(rsa->dmp1, rsa->d, pm1, ctx) || /* Calculate d mod (q-1) */ !BN_mod(rsa->dmq1, rsa->d, qm1, ctx)) { goto bn_err; } /* Sanity-check that |rsa->n| has the specified size. This is implied by * |generate_prime|'s bounds. */ if (BN_num_bits(rsa->n) != (unsigned)bits) { OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); goto err; } /* Calculate inverse of q mod p. Note that although RSA key generation is far * from constant-time, |bn_mod_inverse_secret_prime| uses the same modular * exponentation logic as in RSA private key operations and, if the RSAZ-1024 * code is enabled, will be optimized for common RSA prime sizes. */ if (!BN_MONT_CTX_set_locked(&rsa->mont_p, &rsa->lock, rsa->p, ctx) || !bn_mod_inverse_secret_prime(rsa->iqmp, rsa->q, rsa->p, ctx, rsa->mont_p)) { goto bn_err; } /* The key generation process is complex and thus error-prone. It could be * disastrous to generate and then use a bad key so double-check that the key * makes sense. */ if (!RSA_check_key(rsa)) { OPENSSL_PUT_ERROR(RSA, RSA_R_INTERNAL_ERROR); goto err; } ret = 1; bn_err: if (!ret) { OPENSSL_PUT_ERROR(RSA, ERR_LIB_BN); } err: if (ctx != NULL) { BN_CTX_end(ctx); BN_CTX_free(ctx); } return ret; } int RSA_generate_key_fips(RSA *rsa, int bits, BN_GENCB *cb) { /* FIPS 186-4 allows 2048-bit and 3072-bit RSA keys (1024-bit and 1536-bit * primes, respectively) with the prime generation method we use. */ if (bits != 2048 && bits != 3072) { OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_RSA_PARAMETERS); return 0; } BIGNUM *e = BN_new(); int ret = e != NULL && BN_set_word(e, RSA_F4) && RSA_generate_key_ex(rsa, bits, e, cb) && RSA_check_fips(rsa); BN_free(e); return ret; } DEFINE_METHOD_FUNCTION(RSA_METHOD, RSA_default_method) { /* All of the methods are NULL to make it easier for the compiler/linker to * drop unused functions. The wrapper functions will select the appropriate * |rsa_default_*| implementation. */ OPENSSL_memset(out, 0, sizeof(RSA_METHOD)); out->common.is_static = 1; out->flags = RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE; }