6f122c7f89
Note that there are *two* maximum key size checks in the code, and the one in rsa.rs subsumes the one in rsa_impl.c.
522 lines
15 KiB
C
522 lines
15 KiB
C
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.] */
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#include <openssl/rsa.h>
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#include <assert.h>
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#include <string.h>
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#include <openssl/bn.h>
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#include <openssl/err.h>
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#include <openssl/mem.h>
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#include "internal.h"
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#include "../internal.h"
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/* Declarations to avoid -Wmissing-prototypes warnings. */
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int GFp_rsa_private_transform(RSA *rsa, uint8_t *inout, size_t len,
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BN_BLINDING *blinding, RAND *rng);
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static int check_modulus_and_exponent(const BIGNUM *n, const BIGNUM *e,
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size_t min_bits, size_t max_bits) {
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unsigned rsa_bits = BN_num_bits(n);
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if (rsa_bits < min_bits) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
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return 0;
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}
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/* XXX: There's may be another check for the maximum length in rsa.rs that
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* subsumes this; check that when investigating the code coverage. */
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if (rsa_bits > 16 * 1024 || rsa_bits > max_bits) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_MODULUS_TOO_LARGE);
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return 0;
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}
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/* Mitigate DoS attacks by limiting the exponent size. 33 bits was chosen as
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* the limit based on the recommendations in [1] and [2]. Windows CryptoAPI
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* doesn't support values larger than 32 bits [3], so it is unlikely that
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* exponents larger than 32 bits are being used for anything Windows commonly
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* does.
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*
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* [1] https://www.imperialviolet.org/2012/03/16/rsae.html
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* [2] https://www.imperialviolet.org/2012/03/17/rsados.html
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* [3] https://msdn.microsoft.com/en-us/library/aa387685(VS.85).aspx */
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static const unsigned kMaxExponentBits = 33;
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unsigned e_bits = BN_num_bits(e);
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if (e_bits < 2) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_E_VALUE);
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return 0;
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}
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if (e_bits > kMaxExponentBits) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_E_VALUE);
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return 0;
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}
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if (!BN_is_odd(e)) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_E_VALUE);
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return 0;
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}
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/* Verify |n > e|. Comparing |rsa_bits| to |kMaxExponentBits| is a small
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* shortcut to comparing |n| and |e| directly. In reality, |kMaxExponentBits|
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* is much smaller than the minimum RSA key size that any application should
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* accept. */
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if (rsa_bits <= kMaxExponentBits) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
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return 0;
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}
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assert(BN_ucmp(n, e) > 0);
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return 1;
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}
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size_t RSA_size(const RSA *rsa) {
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return BN_num_bytes(rsa->n);
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}
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/* GFp_rsa_public_decrypt decrypts the RSA signature |in| using the public key
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* with modulus |public_key_n| and exponent |public_key_e|, leaving the
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* decrypted signature in |out|. |out_len| and |in_len| must both be equal to
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* |RSA_size(rsa)|. |min_bits| and |max_bits| are the minimum and maximum
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* allowed public key modulus sizes, in bits. It returns one on success and
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* zero on failure.
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*
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* When |rsa_public_decrypt| succeeds, the caller must then check the
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* signature value (and padding) left in |out|. */
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int GFp_rsa_public_decrypt(uint8_t *out, size_t out_len,
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const uint8_t *public_key_n, size_t public_key_n_len,
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const uint8_t *public_key_e, size_t public_key_e_len,
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const uint8_t *in, size_t in_len, size_t min_bits,
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size_t max_bits) {
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BIGNUM n;
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BN_init(&n);
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BIGNUM e;
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BN_init(&e);
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BIGNUM f;
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BN_init(&f);
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BIGNUM result;
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BN_init(&result);
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BN_CTX *ctx = NULL;
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int ret = 0;
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if (BN_bin2bn(public_key_n, public_key_n_len, &n) == NULL ||
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BN_bin2bn(public_key_e, public_key_e_len, &e) == NULL) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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unsigned rsa_size = BN_num_bytes(&n); /* RSA_size((n, e)); */
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if (out_len != rsa_size) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_OUTPUT_BUFFER_TOO_SMALL);
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goto err;
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}
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if (in_len != rsa_size) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_LEN_NOT_EQUAL_TO_MOD_LEN);
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goto err;
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}
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if (!check_modulus_and_exponent(&n, &e, min_bits, max_bits)) {
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goto err;
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}
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if (BN_bin2bn(in, in_len, &f) == NULL) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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if (BN_ucmp(&f, &n) >= 0) {
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OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
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goto err;
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}
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ctx = BN_CTX_new();
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if (ctx == NULL) {
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goto err;
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}
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if (!BN_mod_exp_mont(&result, &f, &e, &n, ctx, NULL) ||
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!BN_bn2bin_padded(out, out_len, &result)) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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ret = 1;
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err:
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BN_free(&n);
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BN_free(&e);
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BN_free(&f);
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BN_free(&result);
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BN_CTX_free(ctx);
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return ret;
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}
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/* GFp_rsa_private_transform takes a big-endian integer from |inout|,
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* calculates the d'th power of it, modulo the RSA modulus and writes the
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* result as a big-endian integer back to |inout|. |inout| is |len| bytes long
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* and |len| is always equal to |RSA_size(rsa)|. If the result of the transform
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* can be represented in fewer than |len| bytes, then |out| must be zero padded
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* on the left.
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*
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* It returns one on success and zero otherwise.
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*/
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int GFp_rsa_private_transform(RSA *rsa, uint8_t *inout, size_t len,
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BN_BLINDING *blinding, RAND *rng) {
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BN_CTX *ctx = BN_CTX_new();
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if (ctx == NULL) {
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return 0;
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}
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int ret = 0;
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BIGNUM base, r, tmp, mp, mq, vrfy;
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BN_init(&base);
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BN_init(&r);
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BN_init(&tmp);
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BN_init(&mp);
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BN_init(&mq);
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BN_init(&vrfy);
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if (BN_bin2bn(inout, len, &base) == NULL) {
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goto err;
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}
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if (BN_ucmp(&base, rsa->n) >= 0) {
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/* Usually the padding functions would catch this. */
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OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
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goto err;
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}
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if (!BN_BLINDING_convert(&base, blinding, rsa, rng, ctx)) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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/* Extra reductions would be required if |p < q| and |p == q| is just plain
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* wrong. */
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assert(BN_cmp(rsa->q, rsa->p) < 0);
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/* mp := base^dmp1 mod p.
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*
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* |p * q == n| and |p > q| implies |p < n < p**2|. Thus, the base is just
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* reduced mod |p|. */
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assert(BN_get_flags(rsa->p, BN_FLG_CONSTTIME));
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assert(BN_get_flags(rsa->dmp1, BN_FLG_CONSTTIME));
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if (!BN_reduce_montgomery(&tmp, &base, rsa->mont_p, ctx) ||
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!BN_mod_exp_mont_consttime(&mp, &tmp, rsa->dmp1, rsa->p, ctx,
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rsa->mont_p)) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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/* mq := base^dmq1 mod q.
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*
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* |p * q == n| and |p > q| implies |q < q**2 < n < q**3|. Thus, |base| is
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* first reduced mod |q**2| and then reduced mod |q|. */
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assert(BN_get_flags(rsa->q, BN_FLG_CONSTTIME));
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assert(BN_get_flags(rsa->dmq1, BN_FLG_CONSTTIME));
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if (!BN_reduce_montgomery(&tmp, &base, rsa->mont_qq, ctx) ||
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!BN_reduce_montgomery(&tmp, &tmp, rsa->mont_q, ctx) ||
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!BN_mod_exp_mont_consttime(&mq, &tmp, rsa->dmq1, rsa->q, ctx,
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rsa->mont_q)) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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/* Combine them with Garner's algorithm.
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*
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* |0 <= mq < q < p| and |0 <= mp < p| implies |(-q) < (mp - mq) < p|, so
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* |BN_mod_sub_quick| can be used.
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*
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* In each multiplication, the Montgomery factor cancels out because |tmp| is
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* not Montgomery-encoded but the second input is.
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*
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* In the last multiplication, the reduction mod |n| isn't necessary because
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* |tmp < p| and |p * q == n| implies |tmp * q < n|. Montgomery
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* multiplication is used purely because it is implemented more efficiently.
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*/
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if (!BN_mod_sub_quick(&tmp, &mp, &mq, rsa->p) ||
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!BN_mod_mul_montgomery(&tmp, &tmp, rsa->iqmp_mont, rsa->mont_p, ctx) ||
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!BN_mod_mul_montgomery(&tmp, &tmp, rsa->qmn_mont, rsa->mont_n, ctx) ||
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!BN_add(&r, &tmp, &mq)) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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/* Verify the result to protect against fault attacks as described in the
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* 1997 paper "On the Importance of Checking Cryptographic Protocols for
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* Faults" by Dan Boneh, Richard A. DeMillo, and Richard J. Lipton. Some
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* implementations do this only when the CRT is used, but we do it in all
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* cases. Section 6 of the aforementioned paper describes an attack that
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* works when the CRT isn't used. That attack is much less likely to succeed
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* than the CRT attack, but there have likely been improvements since 1997.
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*
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* This check is very cheap assuming |e| is small, which it almost always is. */
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if (!BN_mod_exp_mont(&vrfy, &r, rsa->e, rsa->n, ctx, rsa->mont_n)) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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if (vrfy.top != base.top ||
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CRYPTO_memcmp(vrfy.d, base.d, (size_t)vrfy.top * sizeof(vrfy.d[0])) != 0) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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if (!BN_BLINDING_invert(&r, blinding, rsa->mont_n, ctx) ||
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!BN_bn2bin_padded(inout, len, &r)) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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ret = 1;
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err:
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BN_CTX_free(ctx);
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BN_free(&r);
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BN_free(&tmp);
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BN_free(&mp);
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BN_free(&mq);
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BN_free(&vrfy);
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return ret;
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}
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RSA *RSA_generate(int bits, uint32_t e, RAND *rng, BN_GENCB *cb) {
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RSA *rsa = rsa_new_begin();
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if (rsa == NULL) {
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OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE);
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return NULL;
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}
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BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
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int bitsp, bitsq, ok = -1, n = 0;
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BN_CTX *ctx = NULL;
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ctx = BN_CTX_new();
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if (ctx == NULL) {
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goto err;
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}
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BN_CTX_start(ctx);
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r0 = BN_CTX_get(ctx);
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r1 = BN_CTX_get(ctx);
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r2 = BN_CTX_get(ctx);
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r3 = BN_CTX_get(ctx);
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if (r0 == NULL || r1 == NULL || r2 == NULL || r3 == NULL) {
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goto err;
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}
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bitsp = (bits + 1) / 2;
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bitsq = bits - bitsp;
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rsa->e = BN_new();
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if (rsa->e == NULL ||
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!BN_set_word(rsa->e, e)) {
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goto err;
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}
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/* generate p and q */
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rsa->p = BN_new();
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rsa->q = BN_new();
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if (rsa->p == NULL ||
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rsa->q == NULL) {
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goto err;
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}
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for (;;) {
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if (!BN_generate_prime_ex(rsa->p, bitsp, rng, cb) ||
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!BN_sub(r2, rsa->p, BN_value_one()) ||
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!BN_gcd(r1, r2, rsa->e, ctx)) {
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goto err;
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}
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if (BN_is_one(r1)) {
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break;
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}
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if (!BN_GENCB_call(cb, 2, n++)) {
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goto err;
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}
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}
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if (!BN_GENCB_call(cb, 3, 0)) {
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goto err;
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}
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for (;;) {
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/* When generating ridiculously small keys, we can get stuck
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* continually regenerating the same prime values. Check for
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* this and bail if it happens 3 times. */
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unsigned int degenerate = 0;
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do {
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if (!BN_generate_prime_ex(rsa->q, bitsq, rng, cb)) {
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goto err;
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}
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} while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
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if (degenerate == 3) {
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ok = 0; /* we set our own err */
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OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
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goto err;
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}
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if (!BN_sub(r2, rsa->q, BN_value_one()) ||
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!BN_gcd(r1, r2, rsa->e, ctx)) {
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goto err;
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}
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if (BN_is_one(r1)) {
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break;
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}
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if (!BN_GENCB_call(cb, 2, n++)) {
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goto err;
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}
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}
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if (!BN_GENCB_call(cb, 3, 1)) {
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goto err;
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}
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if (BN_cmp(rsa->p, rsa->q) < 0) {
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tmp = rsa->p;
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rsa->p = rsa->q;
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rsa->q = tmp;
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}
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BN_set_flags(rsa->p, BN_FLG_CONSTTIME);
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BN_set_flags(rsa->q, BN_FLG_CONSTTIME);
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/* calculate n */
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rsa->n = BN_new();
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if (rsa->n == NULL) {
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goto err;
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}
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if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx)) {
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goto err;
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}
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/* calculate d */
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if (!BN_sub(r1, rsa->p, BN_value_one())) {
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goto err; /* p-1 */
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}
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if (!BN_sub(r2, rsa->q, BN_value_one())) {
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goto err; /* q-1 */
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}
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if (!BN_mul(r0, r1, r2, ctx)) {
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goto err; /* (p-1)(q-1) */
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}
|
|
rsa->d = BN_new();
|
|
if (rsa->d == NULL) {
|
|
goto err;
|
|
}
|
|
BN_set_flags(r0, BN_FLG_CONSTTIME);
|
|
if (!BN_mod_inverse(rsa->d, rsa->e, r0, ctx)) {
|
|
goto err; /* d */
|
|
}
|
|
BN_set_flags(rsa->d, BN_FLG_CONSTTIME);
|
|
|
|
/* calculate d mod (p-1) */
|
|
rsa->dmp1 = BN_new();
|
|
if (rsa->dmp1 == NULL) {
|
|
goto err;
|
|
}
|
|
if (!BN_mod(rsa->dmp1, rsa->d, r1, ctx)) {
|
|
goto err;
|
|
}
|
|
BN_set_flags(rsa->dmp1, BN_FLG_CONSTTIME);
|
|
|
|
/* calculate d mod (q-1) */
|
|
rsa->dmq1 = BN_new();
|
|
if (rsa->dmq1 == NULL) {
|
|
goto err;
|
|
}
|
|
if (!BN_mod(rsa->dmq1, rsa->d, r2, ctx)) {
|
|
goto err;
|
|
}
|
|
BN_set_flags(rsa->dmq1, BN_FLG_CONSTTIME);
|
|
|
|
/* calculate inverse of q mod p */
|
|
rsa->iqmp = BN_new();
|
|
if (rsa->iqmp == NULL) {
|
|
goto err;
|
|
}
|
|
if (!BN_mod_inverse(rsa->iqmp, rsa->q, rsa->p, ctx)) {
|
|
goto err;
|
|
}
|
|
BN_set_flags(rsa->iqmp, BN_FLG_CONSTTIME);
|
|
|
|
if (!rsa_new_end(rsa)) {
|
|
goto err;
|
|
}
|
|
|
|
ok = 1;
|
|
|
|
err:
|
|
if (ok == -1) {
|
|
OPENSSL_PUT_ERROR(RSA, ERR_LIB_BN);
|
|
ok = 0;
|
|
}
|
|
if (ctx != NULL) {
|
|
BN_CTX_end(ctx);
|
|
BN_CTX_free(ctx);
|
|
}
|
|
if (!ok) {
|
|
RSA_free(rsa);
|
|
return NULL;
|
|
}
|
|
|
|
return rsa;
|
|
}
|