| /* 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.] |
| */ |
| /* ==================================================================== |
| * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved. |
| * |
| * 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 above 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 acknowledgment: |
| * "This product includes software developed by the OpenSSL Project |
| * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" |
| * |
| * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to |
| * endorse or promote products derived from this software without |
| * prior written permission. For written permission, please contact |
| * openssl-core@openssl.org. |
| * |
| * 5. Products derived from this software may not be called "OpenSSL" |
| * nor may "OpenSSL" appear in their names without prior written |
| * permission of the OpenSSL Project. |
| * |
| * 6. Redistributions of any form whatsoever must retain the following |
| * acknowledgment: |
| * "This product includes software developed by the OpenSSL Project |
| * for use in the OpenSSL Toolkit (http://www.openssl.org/)" |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY |
| * EXPRESSED 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 OpenSSL PROJECT OR |
| * ITS 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. |
| * ==================================================================== |
| * |
| * This product includes cryptographic software written by Eric Young |
| * (eay@cryptsoft.com). This product includes software written by Tim |
| * Hudson (tjh@cryptsoft.com). */ |
| |
| #include <openssl/bn.h> |
| |
| #include <assert.h> |
| #include <limits.h> |
| #include <string.h> |
| |
| #include <openssl/err.h> |
| #include <openssl/rand.h> |
| |
| #include "../../internal.h" |
| #include "../rand/internal.h" |
| #include "../service_indicator/internal.h" |
| #include "internal.h" |
| |
| |
| int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) { |
| if (rnd == NULL) { |
| return 0; |
| } |
| |
| if (top != BN_RAND_TOP_ANY && top != BN_RAND_TOP_ONE && |
| top != BN_RAND_TOP_TWO) { |
| OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); |
| return 0; |
| } |
| |
| if (bottom != BN_RAND_BOTTOM_ANY && bottom != BN_RAND_BOTTOM_ODD) { |
| OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); |
| return 0; |
| } |
| |
| if (bits == 0) { |
| BN_zero(rnd); |
| return 1; |
| } |
| |
| if (bits > INT_MAX - (BN_BITS2 - 1)) { |
| OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG); |
| return 0; |
| } |
| |
| int words = (bits + BN_BITS2 - 1) / BN_BITS2; |
| int bit = (bits - 1) % BN_BITS2; |
| const BN_ULONG kOne = 1; |
| const BN_ULONG kThree = 3; |
| BN_ULONG mask = bit < BN_BITS2 - 1 ? (kOne << (bit + 1)) - 1 : BN_MASK2; |
| if (!bn_wexpand(rnd, words)) { |
| return 0; |
| } |
| |
| FIPS_service_indicator_lock_state(); |
| RAND_bytes((uint8_t *)rnd->d, words * sizeof(BN_ULONG)); |
| FIPS_service_indicator_unlock_state(); |
| |
| rnd->d[words - 1] &= mask; |
| if (top != BN_RAND_TOP_ANY) { |
| if (top == BN_RAND_TOP_TWO && bits > 1) { |
| if (bit == 0) { |
| rnd->d[words - 1] |= 1; |
| rnd->d[words - 2] |= kOne << (BN_BITS2 - 1); |
| } else { |
| rnd->d[words - 1] |= kThree << (bit - 1); |
| } |
| } else { |
| rnd->d[words - 1] |= kOne << bit; |
| } |
| } |
| if (bottom == BN_RAND_BOTTOM_ODD) { |
| rnd->d[0] |= 1; |
| } |
| |
| rnd->neg = 0; |
| rnd->width = words; |
| return 1; |
| } |
| |
| int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) { |
| return BN_rand(rnd, bits, top, bottom); |
| } |
| |
| // bn_less_than_word_mask returns a mask of all ones if the number represented |
| // by |len| words at |a| is less than |b| and zero otherwise. It performs this |
| // computation in time independent of the value of |a|. |b| is assumed public. |
| static crypto_word_t bn_less_than_word_mask(const BN_ULONG *a, size_t len, |
| BN_ULONG b) { |
| if (b == 0) { |
| return CONSTTIME_FALSE_W; |
| } |
| if (len == 0) { |
| return CONSTTIME_TRUE_W; |
| } |
| |
| // |a| < |b| iff a[1..len-1] are all zero and a[0] < b. |
| static_assert(sizeof(BN_ULONG) <= sizeof(crypto_word_t), |
| "crypto_word_t is too small"); |
| crypto_word_t mask = 0; |
| for (size_t i = 1; i < len; i++) { |
| mask |= a[i]; |
| } |
| // |mask| is now zero iff a[1..len-1] are all zero. |
| mask = constant_time_is_zero_w(mask); |
| mask &= constant_time_lt_w(a[0], b); |
| return mask; |
| } |
| |
| int bn_in_range_words(const BN_ULONG *a, BN_ULONG min_inclusive, |
| const BN_ULONG *max_exclusive, size_t len) { |
| crypto_word_t mask = ~bn_less_than_word_mask(a, len, min_inclusive); |
| return mask & bn_less_than_words(a, max_exclusive, len); |
| } |
| |
| static int bn_range_to_mask(size_t *out_words, BN_ULONG *out_mask, |
| size_t min_inclusive, const BN_ULONG *max_exclusive, |
| size_t len) { |
| // The magnitude of |max_exclusive| is assumed public. |
| size_t words = len; |
| while (words > 0 && max_exclusive[words - 1] == 0) { |
| words--; |
| } |
| if (words == 0 || |
| (words == 1 && max_exclusive[0] <= min_inclusive)) { |
| OPENSSL_PUT_ERROR(BN, BN_R_INVALID_RANGE); |
| return 0; |
| } |
| BN_ULONG mask = max_exclusive[words - 1]; |
| // This sets all bits in |mask| below the most significant bit. |
| mask |= mask >> 1; |
| mask |= mask >> 2; |
| mask |= mask >> 4; |
| mask |= mask >> 8; |
| mask |= mask >> 16; |
| #if defined(OPENSSL_64_BIT) |
| mask |= mask >> 32; |
| #endif |
| |
| *out_words = words; |
| *out_mask = mask; |
| return 1; |
| } |
| |
| int bn_rand_range_words(BN_ULONG *out, BN_ULONG min_inclusive, |
| const BN_ULONG *max_exclusive, size_t len, |
| const uint8_t additional_data[32]) { |
| // This function implements the equivalent of steps 4 through 7 of FIPS 186-4 |
| // appendices B.4.2 and B.5.2. When called in those contexts, |max_exclusive| |
| // is n and |min_inclusive| is one. |
| |
| // Compute the bit length of |max_exclusive| (step 1), in terms of a number of |
| // |words| worth of entropy to fill and a mask of bits to clear in the top |
| // word. |
| size_t words; |
| BN_ULONG mask; |
| if (!bn_range_to_mask(&words, &mask, min_inclusive, max_exclusive, len)) { |
| return 0; |
| } |
| |
| // Fill any unused words with zero. |
| OPENSSL_memset(out + words, 0, (len - words) * sizeof(BN_ULONG)); |
| |
| unsigned count = 100; |
| do { |
| if (!--count) { |
| OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_ITERATIONS); |
| return 0; |
| } |
| |
| // Steps 4 and 5. Use |words| and |mask| together to obtain a string of N |
| // bits, where N is the bit length of |max_exclusive|. |
| FIPS_service_indicator_lock_state(); |
| RAND_bytes_with_additional_data((uint8_t *)out, words * sizeof(BN_ULONG), |
| additional_data); |
| FIPS_service_indicator_unlock_state(); |
| out[words - 1] &= mask; |
| |
| // If out >= max_exclusive or out < min_inclusive, retry. This implements |
| // the equivalent of steps 6 and 7 without leaking the value of |out|. The |
| // result of this comparison may be treated as public. It only reveals how |
| // many attempts were needed before we found a value in range. This is |
| // independent of the final secret output, and has a distribution that |
| // depends only on |min_inclusive| and |max_exclusive|, both of which are |
| // public. |
| } while (!constant_time_declassify_int( |
| bn_in_range_words(out, min_inclusive, max_exclusive, words))); |
| return 1; |
| } |
| |
| int BN_rand_range_ex(BIGNUM *r, BN_ULONG min_inclusive, |
| const BIGNUM *max_exclusive) { |
| static const uint8_t kDefaultAdditionalData[32] = {0}; |
| if (!bn_wexpand(r, max_exclusive->width) || |
| !bn_rand_range_words(r->d, min_inclusive, max_exclusive->d, |
| max_exclusive->width, kDefaultAdditionalData)) { |
| return 0; |
| } |
| |
| r->neg = 0; |
| r->width = max_exclusive->width; |
| return 1; |
| } |
| |
| int bn_rand_secret_range(BIGNUM *r, int *out_is_uniform, BN_ULONG min_inclusive, |
| const BIGNUM *max_exclusive) { |
| size_t words; |
| BN_ULONG mask; |
| if (!bn_range_to_mask(&words, &mask, min_inclusive, max_exclusive->d, |
| max_exclusive->width) || |
| !bn_wexpand(r, words)) { |
| return 0; |
| } |
| |
| assert(words > 0); |
| assert(mask != 0); |
| // The range must be large enough for bit tricks to fix invalid values. |
| if (words == 1 && min_inclusive > mask >> 1) { |
| OPENSSL_PUT_ERROR(BN, BN_R_INVALID_RANGE); |
| return 0; |
| } |
| |
| // Select a uniform random number with num_bits(max_exclusive) bits. |
| FIPS_service_indicator_lock_state(); |
| RAND_bytes((uint8_t *)r->d, words * sizeof(BN_ULONG)); |
| FIPS_service_indicator_unlock_state(); |
| r->d[words - 1] &= mask; |
| |
| // Check, in constant-time, if the value is in range. |
| *out_is_uniform = |
| bn_in_range_words(r->d, min_inclusive, max_exclusive->d, words); |
| crypto_word_t in_range = *out_is_uniform; |
| in_range = 0 - in_range; |
| |
| // If the value is not in range, force it to be in range. |
| r->d[0] |= constant_time_select_w(in_range, 0, min_inclusive); |
| r->d[words - 1] &= constant_time_select_w(in_range, BN_MASK2, mask >> 1); |
| declassify_assert( |
| bn_in_range_words(r->d, min_inclusive, max_exclusive->d, words)); |
| |
| r->neg = 0; |
| r->width = (int)words; |
| return 1; |
| } |
| |
| int BN_rand_range(BIGNUM *r, const BIGNUM *range) { |
| return BN_rand_range_ex(r, 0, range); |
| } |
| |
| int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) { |
| return BN_rand_range(r, range); |
| } |