Mercurial > dropbear

annotate libtomcrypt/src/modes/ctr/ctr_start.c @ 404:a588558bfc94

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Fix potential null pointer dereference found by Klokwork
author Matt Johnston <matt@ucc.asn.au>
date Sat, 03 Feb 2007 09:58:14 +0000
parents 1b9e69c058d2
children 0cbe8f6dbf9e
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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 ctr_start.c
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15 CTR implementation, start chain, Tom St Denis
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16 */
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17
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18
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19 #ifdef CTR
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20
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21 /**
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22 Initialize a CTR context
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23 @param cipher The index of the cipher desired
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24 @param IV The initial vector
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25 @param key The secret key
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26 @param keylen The length of the secret key (octets)
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27 @param num_rounds Number of rounds in the cipher desired (0 for default)
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28 @param ctr_mode The counter mode (CTR_COUNTER_LITTLE_ENDIAN or CTR_COUNTER_BIG_ENDIAN)
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29 @param ctr The CTR state to initialize
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30 @return CRYPT_OK if successful
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31 */
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32 int ctr_start( int cipher,
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33 const unsigned char *IV,
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34 const unsigned char *key, int keylen,
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35 int num_rounds, int ctr_mode,
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36 symmetric_CTR *ctr)
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37 {
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38 int x, err;
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39
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40 LTC_ARGCHK(IV != NULL);
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41 LTC_ARGCHK(key != NULL);
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42 LTC_ARGCHK(ctr != NULL);
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43
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44 /* bad param? */
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45 if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
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46 return err;
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47 }
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48
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49 /* setup cipher */
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50 if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ctr->key)) != CRYPT_OK) {
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51 return err;
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52 }
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53
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54 /* copy ctr */
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55 ctr->blocklen = cipher_descriptor[cipher].block_length;
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56 ctr->cipher = cipher;
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57 ctr->padlen = 0;
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58 ctr->mode = ctr_mode;
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59 for (x = 0; x < ctr->blocklen; x++) {
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60 ctr->ctr[x] = IV[x];
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61 }
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62 cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key);
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63 return CRYPT_OK;
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64 }
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65
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66 #endif
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67
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68 /* $Source: /cvs/libtom/libtomcrypt/src/modes/ctr/ctr_start.c,v $ */
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69 /* $Revision: 1.6 $ */
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70 /* $Date: 2005/05/05 14:35:59 $ */