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openssl/crypto/bn/bn_lib.c
Matt Caswell fd7d252060 Tighten up BN_with_flags usage and avoid a reachable assert 
The function rsa_ossl_mod_exp uses the function BN_with_flags to create a
temporary copy (local_r1) of a BIGNUM (r1) with modified flags. This
temporary copy shares some state with the original r1. If the state of r1
gets updated then local_r1's state will be stale. This was occurring in the
function so that when local_r1 was freed a call to bn_check_top was made
which failed an assert due to the stale state. To resolve this we must free
local_r1 immediately after we have finished using it and not wait until the
end of the function.

This problem prompted a review of all BN_with_flag usage within the
codebase. All other usage appears to be correct, although often not
obviously so. This commit refactors things to make it much clearer for
these other uses.

Reviewed-by: Emilia Käsper <emilia@openssl.org>
2015-11-26 10:20:36 +00:00

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/* crypto/bn/bn_lib.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.]
*/
#ifndef BN_DEBUG
# undef NDEBUG /* avoid conflicting definitions */
# define NDEBUG
#endif
#include <assert.h>
#include <limits.h>
#include "internal/cryptlib.h"
#include "bn_lcl.h"
/* This stuff appears to be completely unused, so is deprecated */
#ifndef OPENSSL_NO_DEPRECATED
/*-
* For a 32 bit machine
* 2 - 4 == 128
* 3 - 8 == 256
* 4 - 16 == 512
* 5 - 32 == 1024
* 6 - 64 == 2048
* 7 - 128 == 4096
* 8 - 256 == 8192
*/
static int bn_limit_bits = 0;
static int bn_limit_num = 8; /* (1<<bn_limit_bits) */
static int bn_limit_bits_low = 0;
static int bn_limit_num_low = 8; /* (1<<bn_limit_bits_low) */
static int bn_limit_bits_high = 0;
static int bn_limit_num_high = 8; /* (1<<bn_limit_bits_high) */
static int bn_limit_bits_mont = 0;
static int bn_limit_num_mont = 8; /* (1<<bn_limit_bits_mont) */
void BN_set_params(int mult, int high, int low, int mont)
{
if (mult >= 0) {
if (mult > (int)(sizeof(int) * 8) - 1)
mult = sizeof(int) * 8 - 1;
bn_limit_bits = mult;
bn_limit_num = 1 << mult;
}
if (high >= 0) {
if (high > (int)(sizeof(int) * 8) - 1)
high = sizeof(int) * 8 - 1;
bn_limit_bits_high = high;
bn_limit_num_high = 1 << high;
}
if (low >= 0) {
if (low > (int)(sizeof(int) * 8) - 1)
low = sizeof(int) * 8 - 1;
bn_limit_bits_low = low;
bn_limit_num_low = 1 << low;
}
if (mont >= 0) {
if (mont > (int)(sizeof(int) * 8) - 1)
mont = sizeof(int) * 8 - 1;
bn_limit_bits_mont = mont;
bn_limit_num_mont = 1 << mont;
}
}
int BN_get_params(int which)
{
if (which == 0)
return (bn_limit_bits);
else if (which == 1)
return (bn_limit_bits_high);
else if (which == 2)
return (bn_limit_bits_low);
else if (which == 3)
return (bn_limit_bits_mont);
else
return (0);
}
#endif
const BIGNUM *BN_value_one(void)
{
static const BN_ULONG data_one = 1L;
static const BIGNUM const_one =
{ (BN_ULONG *)&data_one, 1, 1, 0, BN_FLG_STATIC_DATA };
return (&const_one);
}
int BN_num_bits_word(BN_ULONG l)
{
static const unsigned char bits[256] = {
0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
};
#if defined(SIXTY_FOUR_BIT_LONG)
if (l & 0xffffffff00000000L) {
if (l & 0xffff000000000000L) {
if (l & 0xff00000000000000L) {
return (bits[(int)(l >> 56)] + 56);
} else
return (bits[(int)(l >> 48)] + 48);
} else {
if (l & 0x0000ff0000000000L) {
return (bits[(int)(l >> 40)] + 40);
} else
return (bits[(int)(l >> 32)] + 32);
}
} else
#else
# ifdef SIXTY_FOUR_BIT
if (l & 0xffffffff00000000LL) {
if (l & 0xffff000000000000LL) {
if (l & 0xff00000000000000LL) {
return (bits[(int)(l >> 56)] + 56);
} else
return (bits[(int)(l >> 48)] + 48);
} else {
if (l & 0x0000ff0000000000LL) {
return (bits[(int)(l >> 40)] + 40);
} else
return (bits[(int)(l >> 32)] + 32);
}
} else
# endif
#endif
{
#if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
if (l & 0xffff0000L) {
if (l & 0xff000000L)
return (bits[(int)(l >> 24L)] + 24);
else
return (bits[(int)(l >> 16L)] + 16);
} else
#endif
{
#if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
if (l & 0xff00L)
return (bits[(int)(l >> 8)] + 8);
else
#endif
return (bits[(int)(l)]);
}
}
}
int BN_num_bits(const BIGNUM *a)
{
int i = a->top - 1;
bn_check_top(a);
if (BN_is_zero(a))
return 0;
return ((i * BN_BITS2) + BN_num_bits_word(a->d[i]));
}
static void bn_free_d(BIGNUM *a)
{
if (BN_get_flags(a,BN_FLG_SECURE))
OPENSSL_secure_free(a->d);
else
OPENSSL_free(a->d);
}
void BN_clear_free(BIGNUM *a)
{
int i;
if (a == NULL)
return;
bn_check_top(a);
if (a->d != NULL) {
OPENSSL_cleanse(a->d, a->dmax * sizeof(a->d[0]));
if (!BN_get_flags(a, BN_FLG_STATIC_DATA))
bn_free_d(a);
}
i = BN_get_flags(a, BN_FLG_MALLOCED);
OPENSSL_cleanse(a, sizeof(*a));
if (i)
OPENSSL_free(a);
}
void BN_free(BIGNUM *a)
{
if (a == NULL)
return;
bn_check_top(a);
if (!BN_get_flags(a, BN_FLG_STATIC_DATA))
bn_free_d(a);
if (a->flags & BN_FLG_MALLOCED)
OPENSSL_free(a);
else {
#ifndef OPENSSL_NO_DEPRECATED
a->flags |= BN_FLG_FREE;
#endif
a->d = NULL;
}
}
void BN_init(BIGNUM *a)
{
memset(a, 0, sizeof(*a));
bn_check_top(a);
}
BIGNUM *BN_new(void)
{
BIGNUM *ret;
if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
BNerr(BN_F_BN_NEW, ERR_R_MALLOC_FAILURE);
return (NULL);
}
ret->flags = BN_FLG_MALLOCED;
bn_check_top(ret);
return (ret);
}
BIGNUM *BN_secure_new(void)
{
BIGNUM *ret = BN_new();
if (ret != NULL)
ret->flags |= BN_FLG_SECURE;
return (ret);
}
/* This is used both by bn_expand2() and bn_dup_expand() */
/* The caller MUST check that words > b->dmax before calling this */
static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
{
BN_ULONG *A, *a = NULL;
const BN_ULONG *B;
int i;
bn_check_top(b);
if (words > (INT_MAX / (4 * BN_BITS2))) {
BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_BIGNUM_TOO_LONG);
return NULL;
}
if (BN_get_flags(b, BN_FLG_STATIC_DATA)) {
BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
return (NULL);
}
if (BN_get_flags(b,BN_FLG_SECURE))
a = A = OPENSSL_secure_malloc(words * sizeof(*a));
else
a = A = OPENSSL_malloc(words * sizeof(*a));
if (A == NULL) {
BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE);
return (NULL);
}
#ifdef PURIFY
/*
* Valgrind complains in BN_consttime_swap because we process the whole
* array even if it's not initialised yet. This doesn't matter in that
* function - what's important is constant time operation (we're not
* actually going to use the data)
*/
memset(a, 0, sizeof(*a) * words);
#endif
#if 1
B = b->d;
/* Check if the previous number needs to be copied */
if (B != NULL) {
for (i = b->top >> 2; i > 0; i--, A += 4, B += 4) {
/*
* The fact that the loop is unrolled
* 4-wise is a tribute to Intel. It's
* the one that doesn't have enough
* registers to accomodate more data.
* I'd unroll it 8-wise otherwise:-)
*
* <appro@fy.chalmers.se>
*/
BN_ULONG a0, a1, a2, a3;
a0 = B[0];
a1 = B[1];
a2 = B[2];
a3 = B[3];
A[0] = a0;
A[1] = a1;
A[2] = a2;
A[3] = a3;
}
/*
* workaround for ultrix cc: without 'case 0', the optimizer does
* the switch table by doing a=top&3; a--; goto jump_table[a];
* which fails for top== 0
*/
switch (b->top & 3) {
case 3:
A[2] = B[2];
case 2:
A[1] = B[1];
case 1:
A[0] = B[0];
case 0:
;
}
}
#else
memset(A, 0, sizeof(*A) * words);
memcpy(A, b->d, sizeof(b->d[0]) * b->top);
#endif
return (a);
}
/*
* This is an internal function that should not be used in applications. It
* ensures that 'b' has enough room for a 'words' word number and initialises
* any unused part of b->d with leading zeros. It is mostly used by the
* various BIGNUM routines. If there is an error, NULL is returned. If not,
* 'b' is returned.
*/
BIGNUM *bn_expand2(BIGNUM *b, int words)
{
bn_check_top(b);
if (words > b->dmax) {
BN_ULONG *a = bn_expand_internal(b, words);
if (!a)
return NULL;
if (b->d) {
OPENSSL_cleanse(b->d, b->dmax * sizeof(b->d[0]));
bn_free_d(b);
}
b->d = a;
b->dmax = words;
}
bn_check_top(b);
return b;
}
BIGNUM *BN_dup(const BIGNUM *a)
{
BIGNUM *t;
if (a == NULL)
return NULL;
bn_check_top(a);
t = BN_get_flags(a, BN_FLG_SECURE) ? BN_secure_new() : BN_new();
if (t == NULL)
return NULL;
if (!BN_copy(t, a)) {
BN_free(t);
return NULL;
}
bn_check_top(t);
return t;
}
BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
{
int i;
BN_ULONG *A;
const BN_ULONG *B;
bn_check_top(b);
if (a == b)
return (a);
if (bn_wexpand(a, b->top) == NULL)
return (NULL);
#if 1
A = a->d;
B = b->d;
for (i = b->top >> 2; i > 0; i--, A += 4, B += 4) {
BN_ULONG a0, a1, a2, a3;
a0 = B[0];
a1 = B[1];
a2 = B[2];
a3 = B[3];
A[0] = a0;
A[1] = a1;
A[2] = a2;
A[3] = a3;
}
/* ultrix cc workaround, see comments in bn_expand_internal */
switch (b->top & 3) {
case 3:
A[2] = B[2];
case 2:
A[1] = B[1];
case 1:
A[0] = B[0];
case 0:;
}
#else
memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
#endif
a->top = b->top;
a->neg = b->neg;
bn_check_top(a);
return (a);
}
void BN_swap(BIGNUM *a, BIGNUM *b)
{
int flags_old_a, flags_old_b;
BN_ULONG *tmp_d;
int tmp_top, tmp_dmax, tmp_neg;
bn_check_top(a);
bn_check_top(b);
flags_old_a = a->flags;
flags_old_b = b->flags;
tmp_d = a->d;
tmp_top = a->top;
tmp_dmax = a->dmax;
tmp_neg = a->neg;
a->d = b->d;
a->top = b->top;
a->dmax = b->dmax;
a->neg = b->neg;
b->d = tmp_d;
b->top = tmp_top;
b->dmax = tmp_dmax;
b->neg = tmp_neg;
a->flags =
(flags_old_a & BN_FLG_MALLOCED) | (flags_old_b & BN_FLG_STATIC_DATA);
b->flags =
(flags_old_b & BN_FLG_MALLOCED) | (flags_old_a & BN_FLG_STATIC_DATA);
bn_check_top(a);
bn_check_top(b);
}
void BN_clear(BIGNUM *a)
{
bn_check_top(a);
if (a->d != NULL)
memset(a->d, 0, sizeof(*a->d) * a->dmax);
a->top = 0;
a->neg = 0;
}
BN_ULONG BN_get_word(const BIGNUM *a)
{
if (a->top > 1)
return BN_MASK2;
else if (a->top == 1)
return a->d[0];
/* a->top == 0 */
return 0;
}
int BN_set_word(BIGNUM *a, BN_ULONG w)
{
bn_check_top(a);
if (bn_expand(a, (int)sizeof(BN_ULONG) * 8) == NULL)
return (0);
a->neg = 0;
a->d[0] = w;
a->top = (w ? 1 : 0);
bn_check_top(a);
return (1);
}
BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
{
unsigned int i, m;
unsigned int n;
BN_ULONG l;
BIGNUM *bn = NULL;
if (ret == NULL)
ret = bn = BN_new();
if (ret == NULL)
return (NULL);
bn_check_top(ret);
/* Skip leading zero's. */
for ( ; len > 0 && *s == 0; s++, len--)
continue;
n = len;
if (n == 0) {
ret->top = 0;
return (ret);
}
i = ((n - 1) / BN_BYTES) + 1;
m = ((n - 1) % (BN_BYTES));
if (bn_wexpand(ret, (int)i) == NULL) {
BN_free(bn);
return NULL;
}
ret->top = i;
ret->neg = 0;
l = 0;
while (n--) {
l = (l << 8L) | *(s++);
if (m-- == 0) {
ret->d[--i] = l;
l = 0;
m = BN_BYTES - 1;
}
}
/*
* need to call this due to clear byte at top if avoiding having the top
* bit set (-ve number)
*/
bn_correct_top(ret);
return (ret);
}
/* ignore negative */
int BN_bn2bin(const BIGNUM *a, unsigned char *to)
{
int n, i;
BN_ULONG l;
bn_check_top(a);
n = i = BN_num_bytes(a);
while (i--) {
l = a->d[i / BN_BYTES];
*(to++) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return (n);
}
int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
{
int i;
BN_ULONG t1, t2, *ap, *bp;
bn_check_top(a);
bn_check_top(b);
i = a->top - b->top;
if (i != 0)
return (i);
ap = a->d;
bp = b->d;
for (i = a->top - 1; i >= 0; i--) {
t1 = ap[i];
t2 = bp[i];
if (t1 != t2)
return ((t1 > t2) ? 1 : -1);
}
return (0);
}
int BN_cmp(const BIGNUM *a, const BIGNUM *b)
{
int i;
int gt, lt;
BN_ULONG t1, t2;
if ((a == NULL) || (b == NULL)) {
if (a != NULL)
return (-1);
else if (b != NULL)
return (1);
else
return (0);
}
bn_check_top(a);
bn_check_top(b);
if (a->neg != b->neg) {
if (a->neg)
return (-1);
else
return (1);
}
if (a->neg == 0) {
gt = 1;
lt = -1;
} else {
gt = -1;
lt = 1;
}
if (a->top > b->top)
return (gt);
if (a->top < b->top)
return (lt);
for (i = a->top - 1; i >= 0; i--) {
t1 = a->d[i];
t2 = b->d[i];
if (t1 > t2)
return (gt);
if (t1 < t2)
return (lt);
}
return (0);
}
int BN_set_bit(BIGNUM *a, int n)
{
int i, j, k;
if (n < 0)
return 0;
i = n / BN_BITS2;
j = n % BN_BITS2;
if (a->top <= i) {
if (bn_wexpand(a, i + 1) == NULL)
return (0);
for (k = a->top; k < i + 1; k++)
a->d[k] = 0;
a->top = i + 1;
}
a->d[i] |= (((BN_ULONG)1) << j);
bn_check_top(a);
return (1);
}
int BN_clear_bit(BIGNUM *a, int n)
{
int i, j;
bn_check_top(a);
if (n < 0)
return 0;
i = n / BN_BITS2;
j = n % BN_BITS2;
if (a->top <= i)
return (0);
a->d[i] &= (~(((BN_ULONG)1) << j));
bn_correct_top(a);
return (1);
}
int BN_is_bit_set(const BIGNUM *a, int n)
{
int i, j;
bn_check_top(a);
if (n < 0)
return 0;
i = n / BN_BITS2;
j = n % BN_BITS2;
if (a->top <= i)
return 0;
return (int)(((a->d[i]) >> j) & ((BN_ULONG)1));
}
int BN_mask_bits(BIGNUM *a, int n)
{
int b, w;
bn_check_top(a);
if (n < 0)
return 0;
w = n / BN_BITS2;
b = n % BN_BITS2;
if (w >= a->top)
return 0;
if (b == 0)
a->top = w;
else {
a->top = w + 1;
a->d[w] &= ~(BN_MASK2 << b);
}
bn_correct_top(a);
return (1);
}
void BN_set_negative(BIGNUM *a, int b)
{
if (b && !BN_is_zero(a))
a->neg = 1;
else
a->neg = 0;
}
int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
{
int i;
BN_ULONG aa, bb;
aa = a[n - 1];
bb = b[n - 1];
if (aa != bb)
return ((aa > bb) ? 1 : -1);
for (i = n - 2; i >= 0; i--) {
aa = a[i];
bb = b[i];
if (aa != bb)
return ((aa > bb) ? 1 : -1);
}
return (0);
}
/*
* Here follows a specialised variants of bn_cmp_words(). It has the
* property of performing the operation on arrays of different sizes. The
* sizes of those arrays is expressed through cl, which is the common length
* ( basicall, min(len(a),len(b)) ), and dl, which is the delta between the
* two lengths, calculated as len(a)-len(b). All lengths are the number of
* BN_ULONGs...
*/
int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, int cl, int dl)
{
int n, i;
n = cl - 1;
if (dl < 0) {
for (i = dl; i < 0; i++) {
if (b[n - i] != 0)
return -1; /* a < b */
}
}
if (dl > 0) {
for (i = dl; i > 0; i--) {
if (a[n + i] != 0)
return 1; /* a > b */
}
}
return bn_cmp_words(a, b, cl);
}
/*
* Constant-time conditional swap of a and b.
* a and b are swapped if condition is not 0. The code assumes that at most one bit of condition is set.
* nwords is the number of words to swap. The code assumes that at least nwords are allocated in both a and b,
* and that no more than nwords are used by either a or b.
* a and b cannot be the same number
*/
void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
{
BN_ULONG t;
int i;
bn_wcheck_size(a, nwords);
bn_wcheck_size(b, nwords);
assert(a != b);
assert((condition & (condition - 1)) == 0);
assert(sizeof(BN_ULONG) >= sizeof(int));
condition = ((condition - 1) >> (BN_BITS2 - 1)) - 1;
t = (a->top ^ b->top) & condition;
a->top ^= t;
b->top ^= t;
#define BN_CONSTTIME_SWAP(ind) \
do { \
t = (a->d[ind] ^ b->d[ind]) & condition; \
a->d[ind] ^= t; \
b->d[ind] ^= t; \
} while (0)
switch (nwords) {
default:
for (i = 10; i < nwords; i++)
BN_CONSTTIME_SWAP(i);
/* Fallthrough */
case 10:
BN_CONSTTIME_SWAP(9); /* Fallthrough */
case 9:
BN_CONSTTIME_SWAP(8); /* Fallthrough */
case 8:
BN_CONSTTIME_SWAP(7); /* Fallthrough */
case 7:
BN_CONSTTIME_SWAP(6); /* Fallthrough */
case 6:
BN_CONSTTIME_SWAP(5); /* Fallthrough */
case 5:
BN_CONSTTIME_SWAP(4); /* Fallthrough */
case 4:
BN_CONSTTIME_SWAP(3); /* Fallthrough */
case 3:
BN_CONSTTIME_SWAP(2); /* Fallthrough */
case 2:
BN_CONSTTIME_SWAP(1); /* Fallthrough */
case 1:
BN_CONSTTIME_SWAP(0);
}
#undef BN_CONSTTIME_SWAP
}
/* Bits of security, see SP800-57 */
int BN_security_bits(int L, int N)
{
int secbits, bits;
if (L >= 15360)
secbits = 256;
else if (L >= 7690)
secbits = 192;
else if (L >= 3072)
secbits = 128;
else if (L >= 2048)
secbits = 112;
else if (L >= 1024)
secbits = 80;
else
return 0;
if (N == -1)
return secbits;
bits = N / 2;
if (bits < 80)
return 0;
return bits >= secbits ? secbits : bits;
}
void BN_zero_ex(BIGNUM *a)
{
a->top = 0;
a->neg = 0;
}
int BN_abs_is_word(const BIGNUM *a, const BN_ULONG w)
{
return ((a->top == 1) && (a->d[0] == w)) || ((w == 0) && (a->top == 0));
}
int BN_is_zero(const BIGNUM *a)
{
return a->top == 0;
}
int BN_is_one(const BIGNUM *a)
{
return BN_abs_is_word(a, 1) && !a->neg;
}
int BN_is_word(const BIGNUM *a, const BN_ULONG w)
{
return BN_abs_is_word(a, w) && (!w || !a->neg);
}
int BN_is_odd(const BIGNUM *a)
{
return (a->top > 0) && (a->d[0] & 1);
}
int BN_is_negative(const BIGNUM *a)
{
return (a->neg != 0);
}
int BN_to_montgomery(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx)
{
return BN_mod_mul_montgomery(r, a, &(mont->RR), mont, ctx);
}
void BN_with_flags(BIGNUM *dest, const BIGNUM *b, int flags)
{
dest->d = b->d;
dest->top = b->top;
dest->dmax = b->dmax;
dest->neg = b->neg;
dest->flags = ((dest->flags & BN_FLG_MALLOCED)
| (b->flags & ~BN_FLG_MALLOCED)
| BN_FLG_STATIC_DATA | flags);
}
BN_GENCB *BN_GENCB_new(void)
{
BN_GENCB *ret;
if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) {
BNerr(BN_F_BN_GENCB_NEW, ERR_R_MALLOC_FAILURE);
return (NULL);
}
return ret;
}
void BN_GENCB_free(BN_GENCB *cb)
{
if (cb == NULL)
return;
OPENSSL_free(cb);
}
void BN_set_flags(BIGNUM *b, int n)
{
b->flags |= n;
}
int BN_get_flags(const BIGNUM *b, int n)
{
return b->flags & n;
}
/* Populate a BN_GENCB structure with an "old"-style callback */
void BN_GENCB_set_old(BN_GENCB *gencb, void (*callback) (int, int, void *),
void *cb_arg)
{
BN_GENCB *tmp_gencb = gencb;
tmp_gencb->ver = 1;
tmp_gencb->arg = cb_arg;
tmp_gencb->cb.cb_1 = callback;
}
/* Populate a BN_GENCB structure with a "new"-style callback */
void BN_GENCB_set(BN_GENCB *gencb, int (*callback) (int, int, BN_GENCB *),
void *cb_arg)
{
BN_GENCB *tmp_gencb = gencb;
tmp_gencb->ver = 2;
tmp_gencb->arg = cb_arg;
tmp_gencb->cb.cb_2 = callback;
}
void *BN_GENCB_get_arg(BN_GENCB *cb)
{
return cb->arg;
}
BIGNUM *bn_wexpand(BIGNUM *a, int words)
{
return (words <= a->dmax) ? a : bn_expand2(a, words);
}
void bn_correct_top(BIGNUM *a)
{
BN_ULONG *ftl;
int tmp_top = a->top;
if (tmp_top > 0) {
for (ftl = &(a->d[tmp_top - 1]); tmp_top > 0; tmp_top--)
if (*(ftl--))
break;
a->top = tmp_top;
}
bn_pollute(a);
}
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