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openssl/crypto/bn/bn_lib.c
Rich Salz 01c09f9fde Misc BN fixes 
Never output -0; make "negative zero" an impossibility.
Do better checking on BN_rand top/bottom requirements and #bits.
Update doc.
Ignoring trailing garbage in BN_asc2bn.

Port this commit from boringSSL: https://boringssl.googlesource.com/boringssl/+/899b9b19a4cd3fe526aaf5047ab9234cdca19f7d%5E!/
        Ensure |BN_div| never gives negative zero in the no_branch code.

        Have |bn_correct_top| fix |bn->neg| if the input is zero so that we
        don't have negative zeros lying around.

        Thanks to Brian Smith for noticing.

Reviewed-by: Richard Levitte <levitte@openssl.org>
2016-09-06 10:42:01 -04:00

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/*
* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <assert.h>
#include <limits.h>
#include "internal/cryptlib.h"
#include "bn_lcl.h"
#include <openssl/opensslconf.h>
/* This stuff appears to be completely unused, so is deprecated */
#if OPENSSL_API_COMPAT < 0x00908000L
/*-
* 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 {
#if OPENSSL_API_COMPAT < 0x00908000L
a->flags |= BN_FLG_FREE;
#endif
a->d = NULL;
}
}
void bn_init(BIGNUM *a)
{
static BIGNUM nilbn;
*a = nilbn;
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 by bn_expand2() */
/* 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_zalloc(words * sizeof(*a));
else
a = A = OPENSSL_zalloc(words * sizeof(*a));
if (A == NULL) {
BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE);
return (NULL);
}
#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 accommodate 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;
}
switch (b->top & 3) {
case 3:
A[2] = B[2];
case 2:
A[1] = B[1];
case 1:
A[0] = B[0];
case 0:
/* Without the "case 0" some old optimizers got this wrong. */
;
}
}
#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)
OPENSSL_cleanse(a->d, 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 */
static int bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
{
int i;
BN_ULONG l;
bn_check_top(a);
i = BN_num_bytes(a);
if (tolen == -1)
tolen = i;
else if (tolen < i)
return -1;
/* Add leading zeroes if necessary */
if (tolen > i) {
memset(to, 0, tolen - i);
to += tolen - i;
}
while (i--) {
l = a->d[i / BN_BYTES];
*(to++) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return tolen;
}
int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen)
{
if (tolen < 0)
return -1;
return bn2binpad(a, to, tolen);
}
int BN_bn2bin(const BIGNUM *a, unsigned char *to)
{
return bn2binpad(a, to, -1);
}
BIGNUM *BN_lebin2bn(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);
s += len;
/* Skip trailing zeroes. */
for ( ; len > 0 && s[-1] == 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--) {
s--;
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;
}
int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen)
{
int i;
BN_ULONG l;
bn_check_top(a);
i = BN_num_bytes(a);
if (tolen < i)
return -1;
/* Add trailing zeroes if necessary */
if (tolen > i)
memset(to + i, 0, tolen - i);
to += i;
while (i--) {
l = a->d[i / BN_BYTES];
to--;
*to = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return tolen;
}
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
* capability of performing the operation on arrays of different sizes. The
* sizes of those arrays is expressed through cl, which is the common length
* ( basically, 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]); tmp_top > 0; tmp_top--) {
ftl--;
if (*ftl != 0)
break;
}
a->top = tmp_top;
}
if (a->top == 0)
a->neg = 0;
bn_pollute(a);
}
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