1 /* ***** BEGIN LICENSE BLOCK *****
2 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
3 *
4 * The contents of this file are subject to the Mozilla Public License Version
5 * 1.1 (the "License"); you may not use this file except in compliance with
6 * the License. You may obtain a copy of the License at
7 * http://www.mozilla.org/MPL/
8 *
9 * Software distributed under the License is distributed on an "AS IS" basis,
10 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
11 * for the specific language governing rights and limitations under the
12 * License.
13 *
14 * The Original Code is the Netscape security libraries.
15 *
16 * The Initial Developer of the Original Code is
17 * Netscape Communications Corporation.
18 * Portions created by the Initial Developer are Copyright (C) 1994-2000
19 * the Initial Developer. All Rights Reserved.
20 *
21 * Contributor(s):
22 *
23 * Alternatively, the contents of this file may be used under the terms of
24 * either the GNU General Public License Version 2 or later (the "GPL"), or
25 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
26 * in which case the provisions of the GPL or the LGPL are applicable instead
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32 * the provisions above, a recipient may use your version of this file under
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34 *
35 * ***** END LICENSE BLOCK ***** */
36
37 // This file exists to provide the secure memcmp function. This was added in
38 // NSS 3.12.5.
39
40 #include <stdlib.h>
41
42 /*
43 * Perform a constant-time compare of two memory regions. The return value is
44 * 0 if the memory regions are equal and non-zero otherwise.
45 */
46 int
NSS_SecureMemcmp(const void * ia,const void * ib,size_t n)47 NSS_SecureMemcmp(const void *ia, const void *ib, size_t n)
48 {
49 const unsigned char *a = (const unsigned char*) ia;
50 const unsigned char *b = (const unsigned char*) ib;
51 size_t i;
52 unsigned char r = 0;
53
54 for (i = 0; i < n; ++i) {
55 r |= *a++ ^ *b++;
56 }
57
58 return r;
59 }
60