1 /*
2 * Copyright (c) 2015 Google, Inc.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files
6 * (the "Software"), to deal in the Software without restriction,
7 * including without limitation the rights to use, copy, modify, merge,
8 * publish, distribute, sublicense, and/or sell copies of the Software,
9 * and to permit persons to whom the Software is furnished to do so,
10 * subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
18 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
19 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
20 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
21 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
22 */
23
24 #include <lib/tcrypto/tcrypto.h>
25
26 /*
27 * Timing attack resistent memcmp
28 */
tc_memcmp(const void * p1,const void * p2,size_t len)29 int tc_memcmp(const void* p1, const void* p2, size_t len) {
30 uint8_t res = 0;
31 const uint8_t* s1 = p1;
32 const uint8_t* s2 = p2;
33
34 while (len > 0) {
35 res |= *s1++ ^ *s2++;
36 --len;
37 }
38
39 return res;
40 }
41