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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 OFB |
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14 |
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15 int ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb) |
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16 { |
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17 int err; |
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18 _ARGCHK(pt != NULL); |
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19 _ARGCHK(ct != NULL); |
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20 _ARGCHK(ofb != NULL); |
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21 if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) { |
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22 return err; |
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23 } |
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24 |
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25 /* is blocklen/padlen valid? */ |
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26 if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) || |
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27 ofb->padlen < 0 || ofb->padlen > (int)sizeof(ofb->IV)) { |
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28 return CRYPT_INVALID_ARG; |
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29 } |
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30 |
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31 while (len-- > 0) { |
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32 if (ofb->padlen == ofb->blocklen) { |
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33 cipher_descriptor[ofb->cipher].ecb_encrypt(ofb->IV, ofb->IV, &ofb->key); |
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34 ofb->padlen = 0; |
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35 } |
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36 *ct++ = *pt++ ^ ofb->IV[ofb->padlen++]; |
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37 } |
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38 return CRYPT_OK; |
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39 } |
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40 |
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41 #endif |
