-/* crypto/bn/bn_add.c */
-/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
+/*
+ * Copyright 1995-2018 The OpenSSL Project Authors. 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.]
+ * 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 "cryptlib.h"
+#include "internal/cryptlib.h"
#include "bn_lcl.h"
-/* r can == a or b */
+/* signed add of b to a. */
int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
- const BIGNUM *tmp;
- int a_neg = a->neg, ret;
+ int ret, r_neg, cmp_res;
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;
+ if (a->neg == b->neg) {
+ r_neg = a->neg;
+ ret = BN_uadd(r, a, b);
+ } else {
+ cmp_res = BN_ucmp(a, b);
+ if (cmp_res > 0) {
+ r_neg = a->neg;
+ ret = BN_usub(r, a, b);
+ } else if (cmp_res < 0) {
+ r_neg = b->neg;
+ ret = BN_usub(r, b, a);
+ } else {
+ r_neg = 0;
+ BN_zero(r);
+ ret = 1;
}
+ }
+
+ r->neg = r_neg;
+ bn_check_top(r);
+ return ret;
+}
+
+/* signed sub of b from a. */
+int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
+{
+ int ret, r_neg, cmp_res;
- /* we are now a - b */
+ bn_check_top(a);
+ bn_check_top(b);
- if (BN_ucmp(a, b) < 0) {
- if (!BN_usub(r, b, a))
- return (0);
- r->neg = 1;
+ if (a->neg != b->neg) {
+ r_neg = a->neg;
+ ret = BN_uadd(r, a, b);
+ } else {
+ cmp_res = BN_ucmp(a, b);
+ if (cmp_res > 0) {
+ r_neg = a->neg;
+ ret = BN_usub(r, a, b);
+ } else if (cmp_res < 0) {
+ r_neg = !b->neg;
+ ret = BN_usub(r, b, a);
} else {
- if (!BN_usub(r, a, b))
- return (0);
- r->neg = 0;
+ r_neg = 0;
+ BN_zero(r);
+ ret = 1;
}
- return (1);
}
- ret = BN_uadd(r, a, b);
- r->neg = a_neg;
+ r->neg = r_neg;
bn_check_top(r);
return ret;
}
-/* unsigned add of b to a */
+/* unsigned add of b to a, r can be equal to a or b. */
int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
int max, min, dif;
const BN_ULONG *ap, *bp;
BN_ULONG *rp, carry, t1, t2;
- const BIGNUM *tmp;
bn_check_top(a);
bn_check_top(b);
if (a->top < b->top) {
+ const BIGNUM *tmp;
+
tmp = a;
a = b;
b = tmp;
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++;
- }
+ while (dif) {
+ dif--;
+ t1 = *(ap++);
+ t2 = (t1 + carry) & BN_MASK2;
+ *(rp++) = t2;
+ carry &= (t2 == 0);
}
- if (dif && rp != ap)
- while (dif--)
- /* copy remaining words if ap != rp */
- *(rp++) = *(ap++);
+ *rp = carry;
+ r->top += carry;
+
r->neg = 0;
bn_check_top(r);
return 1;
int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
int max, min, dif;
- register BN_ULONG t1, t2, *rp;
- register const BN_ULONG *ap, *bp;
- int i, carry;
+ BN_ULONG t1, t2, borrow, *rp;
+ const BN_ULONG *ap, *bp;
bn_check_top(a);
bn_check_top(b);
if (dif < 0) { /* hmm... should not be happening */
BNerr(BN_F_BN_USUB, BN_R_ARG2_LT_ARG3);
- return (0);
+ return 0;
}
if (bn_wexpand(r, max) == NULL)
- return (0);
+ 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;
- }
- *(rp++) = t1 & BN_MASK2;
- }
-#else
- carry = bn_sub_words(rp, ap, bp, min);
+ borrow = 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;
- }
- }
- memcpy(rp, ap, sizeof(*rp) * (max - i));
-
- 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;
- }
+ while (dif) {
+ dif--;
+ t1 = *(ap++);
+ t2 = (t1 - borrow) & BN_MASK2;
+ *(rp++) = t2;
+ borrow &= (t1 == 0);
}
- if (add) {
- if (!BN_uadd(r, a, b))
- return (0);
- r->neg = neg;
- return (1);
- }
+ while (max && *--rp == 0)
+ max--;
- /* We are actually doing a - b :-) */
+ r->top = max;
+ r->neg = 0;
+ bn_pollute(r);
- 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);
+ return 1;
}
+
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