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annotate libtomcrypt/src/modes/xts/xts_mult_x.c @ 1435:f849a5ca2efc

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update to libtomcrypt 1.17 (with Dropbear changes)
author Matt Johnston <matt@ucc.asn.au>
date Sat, 24 Jun 2017 17:50:50 +0800
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children 6dba84798cd5
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1435
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 *
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9 * Tom St Denis, [email protected], http://libtom.org
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10 */
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11 #include "tomcrypt.h"
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12
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13 /**
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14 Source donated by Elliptic Semiconductor Inc (www.ellipticsemi.com) to the LibTom Projects
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15 */
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16
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17 #ifdef LTC_XTS_MODE
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18
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19 /** multiply by x
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20 @param I The value to multiply by x (LFSR shift)
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21 */
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22 void xts_mult_x(unsigned char *I)
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23 {
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24 int x;
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25 unsigned char t, tt;
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26
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27 for (x = t = 0; x < 16; x++) {
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28 tt = I[x] >> 7;
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29 I[x] = ((I[x] << 1) | t) & 0xFF;
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30 t = tt;
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31 }
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32 if (tt) {
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33 I[0] ^= 0x87;
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34 }
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35 }
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36
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37 #endif
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38
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39 /* $Source$ */
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40 /* $Revision$ */
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41 /* $Date$ */
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42