1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.] */
57 #include <openssl/bn.h>
59 #include <openssl/err.h>
60 #include <openssl/mem.h>
65 int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
67 int a_neg = a->neg, ret;
75 /* only one is negative */
82 /* we are now a - b */
83 if (BN_ucmp(a, b) < 0) {
84 if (!BN_usub(r, b, a)) {
89 if (!BN_usub(r, a, b)) {
97 ret = BN_uadd(r, a, b);
102 int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
104 BN_ULONG *ap, *bp, *rp, carry, t1, t2;
107 if (a->top < b->top) {
116 if (bn_wexpand(r, max + 1) == NULL) {
126 carry = bn_add_words(rp, ap, bp, min);
135 t2 = (t1 + 1) & BN_MASK2;
143 /* carry != 0 => dif == 0 */
149 if (dif && rp != ap) {
151 /* copy remaining words if ap != rp */
160 int BN_add_word(BIGNUM *a, BN_ULONG w) {
166 /* degenerate case: w is zero */
171 /* degenerate case: a is zero */
173 return BN_set_word(a, w);
176 /* handle 'a' when negative */
179 i = BN_sub_word(a, w);
180 if (!BN_is_zero(a)) {
186 for (i = 0; w != 0 && i < a->top; i++) {
187 a->d[i] = l = (a->d[i] + w) & BN_MASK2;
191 if (w && i == a->top) {
192 if (bn_wexpand(a, a->top + 1) == NULL) {
202 int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
204 int add = 0, neg = 0;
229 if (!BN_uadd(r, a, b)) {
237 /* We are actually doing a - b :-) */
239 max = (a->top > b->top) ? a->top : b->top;
240 if (bn_wexpand(r, max) == NULL) {
244 if (BN_ucmp(a, b) < 0) {
245 if (!BN_usub(r, b, a)) {
250 if (!BN_usub(r, a, b)) {
259 int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
261 register BN_ULONG t1, t2, *ap, *bp, *rp;
268 if (dif < 0) /* hmm... should not be happening */
270 OPENSSL_PUT_ERROR(BN, BN_usub, BN_R_ARG2_LT_ARG3);
274 if (bn_wexpand(r, max) == NULL) {
283 for (i = min; i != 0; i--) {
288 t1 = (t1 - t2 - 1) & BN_MASK2;
291 t1 = (t1 - t2) & BN_MASK2;
293 *(rp++) = t1 & BN_MASK2;
296 if (carry) /* subtracted */
306 t2 = (t1 - 1) & BN_MASK2;
344 int BN_sub_word(BIGNUM *a, BN_ULONG w) {
349 /* degenerate case: w is zero */
354 /* degenerate case: a is zero */
356 i = BN_set_word(a, w);
358 BN_set_negative(a, 1);
363 /* handle 'a' when negative */
366 i = BN_add_word(a, w);
371 if ((a->top == 1) && (a->d[0] < w)) {
372 a->d[0] = w - a->d[0];
383 a->d[i] = (a->d[i] - w) & BN_MASK2;
389 if ((a->d[i] == 0) && (i == (a->top - 1))) {