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>
61 #include <openssl/err.h>
62 #include <openssl/mem.h>
67 int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
69 int a_neg = a->neg, ret;
76 // only one is negative
84 if (BN_ucmp(a, b) < 0) {
85 if (!BN_usub(r, b, a)) {
90 if (!BN_usub(r, a, b)) {
98 ret = BN_uadd(r, a, b);
103 int bn_uadd_consttime(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
104 // Widths are public, so we normalize to make |a| the larger one.
105 if (a->width < b->width) {
106 const BIGNUM *tmp = a;
113 if (!bn_wexpand(r, max + 1)) {
118 BN_ULONG carry = bn_add_words(r->d, a->d, b->d, min);
119 for (int i = min; i < max; i++) {
120 // |r| and |a| may alias, so use a temporary.
121 BN_ULONG tmp = carry + a->d[i];
122 carry = tmp < a->d[i];
130 int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
131 if (!bn_uadd_consttime(r, a, b)) {
134 bn_set_minimal_width(r);
138 int BN_add_word(BIGNUM *a, BN_ULONG w) {
142 // degenerate case: w is zero
147 // degenerate case: a is zero
149 return BN_set_word(a, w);
152 // handle 'a' when negative
155 i = BN_sub_word(a, w);
156 if (!BN_is_zero(a)) {
162 for (i = 0; w != 0 && i < a->width; i++) {
163 a->d[i] = l = a->d[i] + w;
167 if (w && i == a->width) {
168 if (!bn_wexpand(a, a->width + 1)) {
178 int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
179 int add = 0, neg = 0;
203 if (!BN_uadd(r, a, b)) {
211 if (BN_ucmp(a, b) < 0) {
212 if (!BN_usub(r, b, a)) {
217 if (!BN_usub(r, a, b)) {
226 int bn_usub_consttime(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
227 // |b| may have more words than |a| given non-minimal inputs, but all words
228 // beyond |a->width| must then be zero.
229 int b_width = b->width;
230 if (b_width > a->width) {
231 if (!bn_fits_in_words(b, a->width)) {
232 OPENSSL_PUT_ERROR(BN, BN_R_ARG2_LT_ARG3);
238 if (!bn_wexpand(r, a->width)) {
242 BN_ULONG borrow = bn_sub_words(r->d, a->d, b->d, b_width);
243 for (int i = b_width; i < a->width; i++) {
244 // |r| and |a| may alias, so use a temporary.
245 BN_ULONG tmp = a->d[i];
246 r->d[i] = a->d[i] - borrow;
247 borrow = tmp < r->d[i];
251 OPENSSL_PUT_ERROR(BN, BN_R_ARG2_LT_ARG3);
260 int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) {
261 if (!bn_usub_consttime(r, a, b)) {
264 bn_set_minimal_width(r);
268 int BN_sub_word(BIGNUM *a, BN_ULONG w) {
271 // degenerate case: w is zero
276 // degenerate case: a is zero
278 i = BN_set_word(a, w);
280 BN_set_negative(a, 1);
285 // handle 'a' when negative
288 i = BN_add_word(a, w);
293 if ((bn_minimal_width(a) == 1) && (a->d[0] < w)) {
294 a->d[0] = w - a->d[0];
311 if ((a->d[i] == 0) && (i == (a->width - 1))) {