ref: 2bbc75bddc6f2a07056ff017108e35f14061041b
dir: /third_party/boringssl/src/crypto/fipsmodule/bn/random.c/
/* 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 <limits.h>
#include <string.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include <openssl/type_check.h>
#include "internal.h"
#include "../../internal.h"
#include "../rand/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;
}
RAND_bytes((uint8_t *)rnd->d, words * sizeof(BN_ULONG));
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.
OPENSSL_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|.
RAND_bytes_with_additional_data((uint8_t *)out, words * sizeof(BN_ULONG),
additional_data);
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|.
} while (!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.
RAND_bytes((uint8_t *)r->d, words * sizeof(BN_ULONG));
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);
assert(bn_in_range_words(r->d, min_inclusive, max_exclusive->d, words));
r->neg = 0;
r->width = 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);
}