ref: e86bd6a50933e99899d63de755d81b9805827a15
dir: /third_party/boringssl/src/crypto/fipsmodule/bn/bn.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.] */
#include <openssl/bn.h>
#include <limits.h>
#include <string.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include "internal.h"
#include "../delocate.h"
BIGNUM *BN_new(void) {
BIGNUM *bn = OPENSSL_malloc(sizeof(BIGNUM));
if (bn == NULL) {
OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
return NULL;
}
OPENSSL_memset(bn, 0, sizeof(BIGNUM));
bn->flags = BN_FLG_MALLOCED;
return bn;
}
void BN_init(BIGNUM *bn) {
OPENSSL_memset(bn, 0, sizeof(BIGNUM));
}
void BN_free(BIGNUM *bn) {
if (bn == NULL) {
return;
}
if ((bn->flags & BN_FLG_STATIC_DATA) == 0) {
OPENSSL_free(bn->d);
}
if (bn->flags & BN_FLG_MALLOCED) {
OPENSSL_free(bn);
} else {
bn->d = NULL;
}
}
void BN_clear_free(BIGNUM *bn) {
BN_free(bn);
}
BIGNUM *BN_dup(const BIGNUM *src) {
BIGNUM *copy;
if (src == NULL) {
return NULL;
}
copy = BN_new();
if (copy == NULL) {
return NULL;
}
if (!BN_copy(copy, src)) {
BN_free(copy);
return NULL;
}
return copy;
}
BIGNUM *BN_copy(BIGNUM *dest, const BIGNUM *src) {
if (src == dest) {
return dest;
}
if (!bn_wexpand(dest, src->width)) {
return NULL;
}
OPENSSL_memcpy(dest->d, src->d, sizeof(src->d[0]) * src->width);
dest->width = src->width;
dest->neg = src->neg;
return dest;
}
void BN_clear(BIGNUM *bn) {
if (bn->d != NULL) {
OPENSSL_memset(bn->d, 0, bn->dmax * sizeof(bn->d[0]));
}
bn->width = 0;
bn->neg = 0;
}
DEFINE_METHOD_FUNCTION(BIGNUM, BN_value_one) {
static const BN_ULONG kOneLimbs[1] = { 1 };
out->d = (BN_ULONG*) kOneLimbs;
out->width = 1;
out->dmax = 1;
out->neg = 0;
out->flags = BN_FLG_STATIC_DATA;
}
// BN_num_bits_word returns the minimum number of bits needed to represent the
// value in |l|.
unsigned BN_num_bits_word(BN_ULONG l) {
// |BN_num_bits| is often called on RSA prime factors. These have public bit
// lengths, but all bits beyond the high bit are secret, so count bits in
// constant time.
BN_ULONG x, mask;
int bits = (l != 0);
#if BN_BITS2 > 32
// Look at the upper half of |x|. |x| is at most 64 bits long.
x = l >> 32;
// Set |mask| to all ones if |x| (the top 32 bits of |l|) is non-zero and all
// all zeros otherwise.
mask = 0u - x;
mask = (0u - (mask >> (BN_BITS2 - 1)));
// If |x| is non-zero, the lower half is included in the bit count in full,
// and we count the upper half. Otherwise, we count the lower half.
bits += 32 & mask;
l ^= (x ^ l) & mask; // |l| is |x| if |mask| and remains |l| otherwise.
#endif
// The remaining blocks are analogous iterations at lower powers of two.
x = l >> 16;
mask = 0u - x;
mask = (0u - (mask >> (BN_BITS2 - 1)));
bits += 16 & mask;
l ^= (x ^ l) & mask;
x = l >> 8;
mask = 0u - x;
mask = (0u - (mask >> (BN_BITS2 - 1)));
bits += 8 & mask;
l ^= (x ^ l) & mask;
x = l >> 4;
mask = 0u - x;
mask = (0u - (mask >> (BN_BITS2 - 1)));
bits += 4 & mask;
l ^= (x ^ l) & mask;
x = l >> 2;
mask = 0u - x;
mask = (0u - (mask >> (BN_BITS2 - 1)));
bits += 2 & mask;
l ^= (x ^ l) & mask;
x = l >> 1;
mask = 0u - x;
mask = (0u - (mask >> (BN_BITS2 - 1)));
bits += 1 & mask;
return bits;
}
unsigned BN_num_bits(const BIGNUM *bn) {
const int width = bn_minimal_width(bn);
if (width == 0) {
return 0;
}
return (width - 1) * BN_BITS2 + BN_num_bits_word(bn->d[width - 1]);
}
unsigned BN_num_bytes(const BIGNUM *bn) {
return (BN_num_bits(bn) + 7) / 8;
}
void BN_zero(BIGNUM *bn) {
bn->width = bn->neg = 0;
}
int BN_one(BIGNUM *bn) {
return BN_set_word(bn, 1);
}
int BN_set_word(BIGNUM *bn, BN_ULONG value) {
if (value == 0) {
BN_zero(bn);
return 1;
}
if (!bn_wexpand(bn, 1)) {
return 0;
}
bn->neg = 0;
bn->d[0] = value;
bn->width = 1;
return 1;
}
int BN_set_u64(BIGNUM *bn, uint64_t value) {
#if BN_BITS2 == 64
return BN_set_word(bn, value);
#elif BN_BITS2 == 32
if (value <= BN_MASK2) {
return BN_set_word(bn, (BN_ULONG)value);
}
if (!bn_wexpand(bn, 2)) {
return 0;
}
bn->neg = 0;
bn->d[0] = (BN_ULONG)value;
bn->d[1] = (BN_ULONG)(value >> 32);
bn->width = 2;
return 1;
#else
#error "BN_BITS2 must be 32 or 64."
#endif
}
int bn_set_words(BIGNUM *bn, const BN_ULONG *words, size_t num) {
if (!bn_wexpand(bn, num)) {
return 0;
}
OPENSSL_memmove(bn->d, words, num * sizeof(BN_ULONG));
// |bn_wexpand| verified that |num| isn't too large.
bn->width = (int)num;
bn->neg = 0;
return 1;
}
void bn_set_static_words(BIGNUM *bn, const BN_ULONG *words, size_t num) {
if ((bn->flags & BN_FLG_STATIC_DATA) == 0) {
OPENSSL_free(bn->d);
}
bn->d = (BN_ULONG *)words;
bn->width = num;
bn->dmax = num;
bn->neg = 0;
bn->flags |= BN_FLG_STATIC_DATA;
}
int bn_fits_in_words(const BIGNUM *bn, size_t num) {
// All words beyond |num| must be zero.
BN_ULONG mask = 0;
for (size_t i = num; i < (size_t)bn->width; i++) {
mask |= bn->d[i];
}
return mask == 0;
}
int bn_copy_words(BN_ULONG *out, size_t num, const BIGNUM *bn) {
if (bn->neg) {
OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER);
return 0;
}
size_t width = (size_t)bn->width;
if (width > num) {
if (!bn_fits_in_words(bn, num)) {
OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG);
return 0;
}
width = num;
}
OPENSSL_memset(out, 0, sizeof(BN_ULONG) * num);
OPENSSL_memcpy(out, bn->d, sizeof(BN_ULONG) * width);
return 1;
}
int BN_is_negative(const BIGNUM *bn) {
return bn->neg != 0;
}
void BN_set_negative(BIGNUM *bn, int sign) {
if (sign && !BN_is_zero(bn)) {
bn->neg = 1;
} else {
bn->neg = 0;
}
}
int bn_wexpand(BIGNUM *bn, size_t words) {
BN_ULONG *a;
if (words <= (size_t)bn->dmax) {
return 1;
}
if (words > (INT_MAX / (4 * BN_BITS2))) {
OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG);
return 0;
}
if (bn->flags & BN_FLG_STATIC_DATA) {
OPENSSL_PUT_ERROR(BN, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
return 0;
}
a = OPENSSL_malloc(sizeof(BN_ULONG) * words);
if (a == NULL) {
OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
return 0;
}
OPENSSL_memcpy(a, bn->d, sizeof(BN_ULONG) * bn->width);
OPENSSL_free(bn->d);
bn->d = a;
bn->dmax = (int)words;
return 1;
}
int bn_expand(BIGNUM *bn, size_t bits) {
if (bits + BN_BITS2 - 1 < bits) {
OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG);
return 0;
}
return bn_wexpand(bn, (bits+BN_BITS2-1)/BN_BITS2);
}
int bn_resize_words(BIGNUM *bn, size_t words) {
#if defined(OPENSSL_PPC64LE)
// This is a workaround for a miscompilation bug in Clang 7.0.1 on POWER.
// The unittests catch the miscompilation, if it occurs, and it manifests
// as a crash in |bn_fits_in_words|.
//
// The bug only triggers if building in FIPS mode and with -O3. Clang 8.0.1
// has the same bug but this workaround is not effective there---I've not
// been able to find a workaround for 8.0.1.
//
// At the time of writing (2019-08-08), Clang git does *not* have this bug
// and does not need this workaroud. The current git version should go on to
// be Clang 10 thus, once we can depend on that, this can be removed.
if (value_barrier_w((size_t)bn->width == words)) {
return 1;
}
#endif
if ((size_t)bn->width <= words) {
if (!bn_wexpand(bn, words)) {
return 0;
}
OPENSSL_memset(bn->d + bn->width, 0,
(words - bn->width) * sizeof(BN_ULONG));
bn->width = words;
return 1;
}
// All words beyond the new width must be zero.
if (!bn_fits_in_words(bn, words)) {
OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG);
return 0;
}
bn->width = words;
return 1;
}
void bn_select_words(BN_ULONG *r, BN_ULONG mask, const BN_ULONG *a,
const BN_ULONG *b, size_t num) {
for (size_t i = 0; i < num; i++) {
OPENSSL_STATIC_ASSERT(sizeof(BN_ULONG) <= sizeof(crypto_word_t),
"crypto_word_t is too small");
r[i] = constant_time_select_w(mask, a[i], b[i]);
}
}
int bn_minimal_width(const BIGNUM *bn) {
int ret = bn->width;
while (ret > 0 && bn->d[ret - 1] == 0) {
ret--;
}
return ret;
}
void bn_set_minimal_width(BIGNUM *bn) {
bn->width = bn_minimal_width(bn);
if (bn->width == 0) {
bn->neg = 0;
}
}