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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://libtomcrypt.org |
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10 */ |
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11 #include "mycrypt.h" |
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12 |
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13 #ifdef CTR |
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14 |
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15 int ctr_start(int cipher, const unsigned char *count, const unsigned char *key, int keylen, |
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16 int num_rounds, symmetric_CTR *ctr) |
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17 { |
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18 int x, err; |
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19 |
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20 _ARGCHK(count != NULL); |
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21 _ARGCHK(key != NULL); |
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22 _ARGCHK(ctr != NULL); |
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23 |
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24 /* bad param? */ |
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25 if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { |
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26 return err; |
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27 } |
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28 |
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29 /* setup cipher */ |
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30 if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ctr->key)) != CRYPT_OK) { |
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31 return err; |
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32 } |
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33 |
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34 /* copy ctr */ |
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35 ctr->blocklen = cipher_descriptor[cipher].block_length; |
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36 ctr->cipher = cipher; |
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37 ctr->padlen = 0; |
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38 ctr->mode = 0; |
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39 for (x = 0; x < ctr->blocklen; x++) { |
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40 ctr->ctr[x] = count[x]; |
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41 } |
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42 cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key); |
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43 return CRYPT_OK; |
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44 } |
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45 |
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46 #endif |
