314 lines
8.0 KiB
C
314 lines
8.0 KiB
C
/* crypto/bn/bn_add.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 <stdio.h>
|
|
#include "cryptlib.h"
|
|
#include "bn_lcl.h"
|
|
|
|
/* r can == a or b */
|
|
int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
|
|
{
|
|
const BIGNUM *tmp;
|
|
int a_neg = a->neg, ret;
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
|
|
/*-
|
|
* a + b a+b
|
|
* a + -b a-b
|
|
* -a + b b-a
|
|
* -a + -b -(a+b)
|
|
*/
|
|
if (a_neg ^ b->neg) {
|
|
/* only one is negative */
|
|
if (a_neg) {
|
|
tmp = a;
|
|
a = b;
|
|
b = tmp;
|
|
}
|
|
|
|
/* we are now a - b */
|
|
|
|
if (BN_ucmp(a, b) < 0) {
|
|
if (!BN_usub(r, b, a))
|
|
return (0);
|
|
r->neg = 1;
|
|
} else {
|
|
if (!BN_usub(r, a, b))
|
|
return (0);
|
|
r->neg = 0;
|
|
}
|
|
return (1);
|
|
}
|
|
|
|
ret = BN_uadd(r, a, b);
|
|
r->neg = a_neg;
|
|
bn_check_top(r);
|
|
return ret;
|
|
}
|
|
|
|
/* unsigned add of b to a */
|
|
int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
|
|
{
|
|
int max, min, dif;
|
|
BN_ULONG *ap, *bp, *rp, carry, t1, t2;
|
|
const BIGNUM *tmp;
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
|
|
if (a->top < b->top) {
|
|
tmp = a;
|
|
a = b;
|
|
b = tmp;
|
|
}
|
|
max = a->top;
|
|
min = b->top;
|
|
dif = max - min;
|
|
|
|
if (bn_wexpand(r, max + 1) == NULL)
|
|
return 0;
|
|
|
|
r->top = max;
|
|
|
|
ap = a->d;
|
|
bp = b->d;
|
|
rp = r->d;
|
|
|
|
carry = bn_add_words(rp, ap, bp, min);
|
|
rp += min;
|
|
ap += min;
|
|
bp += min;
|
|
|
|
if (carry) {
|
|
while (dif) {
|
|
dif--;
|
|
t1 = *(ap++);
|
|
t2 = (t1 + 1) & BN_MASK2;
|
|
*(rp++) = t2;
|
|
if (t2) {
|
|
carry = 0;
|
|
break;
|
|
}
|
|
}
|
|
if (carry) {
|
|
/* carry != 0 => dif == 0 */
|
|
*rp = 1;
|
|
r->top++;
|
|
}
|
|
}
|
|
if (dif && rp != ap)
|
|
while (dif--)
|
|
/* copy remaining words if ap != rp */
|
|
*(rp++) = *(ap++);
|
|
r->neg = 0;
|
|
bn_check_top(r);
|
|
return 1;
|
|
}
|
|
|
|
/* unsigned subtraction of b from a, a must be larger than b. */
|
|
int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
|
|
{
|
|
int max, min, dif;
|
|
register BN_ULONG t1, t2, *ap, *bp, *rp;
|
|
int i, carry;
|
|
#if defined(IRIX_CC_BUG) && !defined(LINT)
|
|
int dummy;
|
|
#endif
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
|
|
max = a->top;
|
|
min = b->top;
|
|
dif = max - min;
|
|
|
|
if (dif < 0) { /* hmm... should not be happening */
|
|
BNerr(BN_F_BN_USUB, BN_R_ARG2_LT_ARG3);
|
|
return (0);
|
|
}
|
|
|
|
if (bn_wexpand(r, max) == NULL)
|
|
return (0);
|
|
|
|
ap = a->d;
|
|
bp = b->d;
|
|
rp = r->d;
|
|
|
|
#if 1
|
|
carry = 0;
|
|
for (i = min; i != 0; i--) {
|
|
t1 = *(ap++);
|
|
t2 = *(bp++);
|
|
if (carry) {
|
|
carry = (t1 <= t2);
|
|
t1 = (t1 - t2 - 1) & BN_MASK2;
|
|
} else {
|
|
carry = (t1 < t2);
|
|
t1 = (t1 - t2) & BN_MASK2;
|
|
}
|
|
# if defined(IRIX_CC_BUG) && !defined(LINT)
|
|
dummy = t1;
|
|
# endif
|
|
*(rp++) = t1 & BN_MASK2;
|
|
}
|
|
#else
|
|
carry = bn_sub_words(rp, ap, bp, min);
|
|
ap += min;
|
|
bp += min;
|
|
rp += min;
|
|
#endif
|
|
if (carry) { /* subtracted */
|
|
if (!dif)
|
|
/* error: a < b */
|
|
return 0;
|
|
while (dif) {
|
|
dif--;
|
|
t1 = *(ap++);
|
|
t2 = (t1 - 1) & BN_MASK2;
|
|
*(rp++) = t2;
|
|
if (t1)
|
|
break;
|
|
}
|
|
}
|
|
#if 0
|
|
memcpy(rp, ap, sizeof(*rp) * (max - i));
|
|
#else
|
|
if (rp != ap) {
|
|
for (;;) {
|
|
if (!dif--)
|
|
break;
|
|
rp[0] = ap[0];
|
|
if (!dif--)
|
|
break;
|
|
rp[1] = ap[1];
|
|
if (!dif--)
|
|
break;
|
|
rp[2] = ap[2];
|
|
if (!dif--)
|
|
break;
|
|
rp[3] = ap[3];
|
|
rp += 4;
|
|
ap += 4;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
r->top = max;
|
|
r->neg = 0;
|
|
bn_correct_top(r);
|
|
return (1);
|
|
}
|
|
|
|
int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
|
|
{
|
|
int max;
|
|
int add = 0, neg = 0;
|
|
const BIGNUM *tmp;
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
|
|
/*-
|
|
* a - b a-b
|
|
* a - -b a+b
|
|
* -a - b -(a+b)
|
|
* -a - -b b-a
|
|
*/
|
|
if (a->neg) {
|
|
if (b->neg) {
|
|
tmp = a;
|
|
a = b;
|
|
b = tmp;
|
|
} else {
|
|
add = 1;
|
|
neg = 1;
|
|
}
|
|
} else {
|
|
if (b->neg) {
|
|
add = 1;
|
|
neg = 0;
|
|
}
|
|
}
|
|
|
|
if (add) {
|
|
if (!BN_uadd(r, a, b))
|
|
return (0);
|
|
r->neg = neg;
|
|
return (1);
|
|
}
|
|
|
|
/* We are actually doing a - b :-) */
|
|
|
|
max = (a->top > b->top) ? a->top : b->top;
|
|
if (bn_wexpand(r, max) == NULL)
|
|
return (0);
|
|
if (BN_ucmp(a, b) < 0) {
|
|
if (!BN_usub(r, b, a))
|
|
return (0);
|
|
r->neg = 1;
|
|
} else {
|
|
if (!BN_usub(r, a, b))
|
|
return (0);
|
|
r->neg = 0;
|
|
}
|
|
bn_check_top(r);
|
|
return (1);
|
|
}
|