pigweed / third_party / boringssl / boringssl / 5f43b12d52e94b50e481bae2ccb74ab95904123d / . / 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); | |

} |