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annotate src/modes/ofb/ofb_encrypt.c @ 191:1c15b283127b libtomcrypt-orig

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Import of libtomcrypt 1.02 with manual path rename rearrangement etc
author Matt Johnston <matt@ucc.asn.au>
date Fri, 06 May 2005 13:23:02 +0000
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children 39d5d58461d6
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191
1c15b283127b Import of libtomcrypt 1.02 with manual path rename rearrangement etc
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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 "tomcrypt.h"
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12
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13 /**
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14 @file ofb_encrypt.c
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15 OFB implementation, encrypt data, Tom St Denis
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16 */
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17
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18 #ifdef OFB
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19
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20 /**
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21 OFB encrypt
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22 @param pt Plaintext
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23 @param ct [out] Ciphertext
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24 @param len Length of plaintext (octets)
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25 @param ofb OFB state
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26 @return CRYPT_OK if successful
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27 */
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28 int ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb)
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29 {
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30 int err;
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31 LTC_ARGCHK(pt != NULL);
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32 LTC_ARGCHK(ct != NULL);
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33 LTC_ARGCHK(ofb != NULL);
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34 if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) {
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35 return err;
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36 }
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37
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38 /* is blocklen/padlen valid? */
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39 if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) ||
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40 ofb->padlen < 0 || ofb->padlen > (int)sizeof(ofb->IV)) {
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41 return CRYPT_INVALID_ARG;
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42 }
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43
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44 while (len-- > 0) {
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45 if (ofb->padlen == ofb->blocklen) {
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46 cipher_descriptor[ofb->cipher].ecb_encrypt(ofb->IV, ofb->IV, &ofb->key);
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47 ofb->padlen = 0;
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48 }
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49 *ct++ = *pt++ ^ ofb->IV[ofb->padlen++];
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50 }
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51 return CRYPT_OK;
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52 }
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53
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54 #endif