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- /* 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 <string.h>
-
- #include <openssl/err.h>
- #include <openssl/mem.h>
-
- #include "internal.h"
-
-
- int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
- const BIGNUM *tmp;
- int a_neg = a->neg, ret;
-
- /* 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;
- return ret;
- }
-
- 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;
-
- 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;
- return 1;
- }
-
- int BN_add_word(BIGNUM *a, BN_ULONG w) {
- BN_ULONG l;
- int i;
-
- w &= BN_MASK2;
-
- /* degenerate case: w is zero */
- if (!w) {
- return 1;
- }
-
- /* degenerate case: a is zero */
- if (BN_is_zero(a)) {
- return BN_set_word(a, w);
- }
-
- /* handle 'a' when negative */
- if (a->neg) {
- a->neg = 0;
- i = BN_sub_word(a, w);
- if (!BN_is_zero(a)) {
- a->neg = !(a->neg);
- }
- return i;
- }
-
- for (i = 0; w != 0 && i < a->top; i++) {
- a->d[i] = l = (a->d[i] + w) & BN_MASK2;
- w = (w > l) ? 1 : 0;
- }
-
- if (w && i == a->top) {
- if (bn_wexpand(a, a->top + 1) == NULL) {
- return 0;
- }
- a->top++;
- a->d[i] = w;
- }
-
- return 1;
- }
-
- int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
- int max;
- int add = 0, neg = 0;
- const BIGNUM *tmp;
-
- /* 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;
- }
-
- return 1;
- }
-
- 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;
-
- max = a->top;
- min = b->top;
- dif = max - min;
-
- if (dif < 0) /* hmm... should not be happening */
- {
- OPENSSL_PUT_ERROR(BN, BN_R_ARG2_LT_ARG3);
- return 0;
- }
-
- if (bn_wexpand(r, max) == NULL) {
- return 0;
- }
-
- ap = a->d;
- bp = b->d;
- rp = r->d;
-
- 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;
- }
-
- 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 (dif > 0 && rp != ap) {
- memcpy(rp, ap, sizeof(*rp) * dif);
- }
-
- r->top = max;
- r->neg = 0;
- bn_correct_top(r);
-
- return 1;
- }
-
- int BN_sub_word(BIGNUM *a, BN_ULONG w) {
- int i;
-
- w &= BN_MASK2;
-
- /* degenerate case: w is zero */
- if (!w) {
- return 1;
- }
-
- /* degenerate case: a is zero */
- if (BN_is_zero(a)) {
- i = BN_set_word(a, w);
- if (i != 0) {
- BN_set_negative(a, 1);
- }
- return i;
- }
-
- /* handle 'a' when negative */
- if (a->neg) {
- a->neg = 0;
- i = BN_add_word(a, w);
- a->neg = 1;
- return i;
- }
-
- if ((a->top == 1) && (a->d[0] < w)) {
- a->d[0] = w - a->d[0];
- a->neg = 1;
- return 1;
- }
-
- i = 0;
- for (;;) {
- if (a->d[i] >= w) {
- a->d[i] -= w;
- break;
- } else {
- a->d[i] = (a->d[i] - w) & BN_MASK2;
- i++;
- w = 1;
- }
- }
-
- if ((a->d[i] == 0) && (i == (a->top - 1))) {
- a->top--;
- }
-
- return 1;
- }
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