Mercurial > dropbear
annotate libtomcrypt/src/modes/xts/xts_mult_x.c @ 1689:d2d3b5ba6c64
update travis to Ubuntu focal to provide chacha20
author | Matt Johnston <matt@ucc.asn.au> |
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date | Tue, 26 May 2020 23:13:48 +0800 |
parents | 6dba84798cd5 |
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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 #include "tomcrypt.h" |
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10 |
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11 /** |
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12 Source donated by Elliptic Semiconductor Inc (www.ellipticsemi.com) to the LibTom Projects |
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13 */ |
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14 |
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15 #ifdef LTC_XTS_MODE |
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16 |
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17 /** multiply by x |
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18 @param I The value to multiply by x (LFSR shift) |
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19 */ |
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20 void xts_mult_x(unsigned char *I) |
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21 { |
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22 int x; |
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23 unsigned char t, tt; |
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24 |
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25 for (x = t = 0; x < 16; x++) { |
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26 tt = I[x] >> 7; |
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27 I[x] = ((I[x] << 1) | t) & 0xFF; |
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28 t = tt; |
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29 } |
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30 if (tt) { |
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31 I[0] ^= 0x87; |
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32 } |
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33 } |
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34 |
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35 #endif |
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36 |
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37 /* ref: $Format:%D$ */ |
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38 /* git commit: $Format:%H$ */ |
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39 /* commit time: $Format:%ai$ */ |