Mercurial > dropbear

annotate src/encauth/ocb/ocb_decrypt_verify_memory.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
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12 /**
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13 @file ocb_decrypt_verify_memory.c
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14 OCB implementation, helper to decrypt block of memory, by Tom St Denis
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15 */
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16 #include "tomcrypt.h"
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17
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18 #ifdef OCB_MODE
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19
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20 /**
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21 Decrypt and compare the tag with OCB.
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22 @param cipher The index of the cipher desired
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23 @param key The secret key
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24 @param keylen The length of the secret key (octets)
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25 @param nonce The session nonce (length of the block size of the block cipher)
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26 @param ct The ciphertext
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27 @param ctlen The length of the ciphertext (octets)
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28 @param pt [out] The plaintext
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29 @param tag The tag to compare against
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30 @param taglen The length of the tag (octets)
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31 @param stat [out] The result of the tag comparison (1==valid, 0==invalid)
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32 @return CRYPT_OK if successful regardless of the tag comparison
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33 */
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34 int ocb_decrypt_verify_memory(int cipher,
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35 const unsigned char *key, unsigned long keylen,
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36 const unsigned char *nonce,
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37 const unsigned char *ct, unsigned long ctlen,
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38 unsigned char *pt,
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39 const unsigned char *tag, unsigned long taglen,
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40 int *stat)
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41 {
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42 int err;
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43 ocb_state *ocb;
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44
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45 LTC_ARGCHK(key != NULL);
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46 LTC_ARGCHK(nonce != NULL);
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47 LTC_ARGCHK(pt != NULL);
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48 LTC_ARGCHK(ct != NULL);
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49 LTC_ARGCHK(tag != NULL);
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50 LTC_ARGCHK(stat != NULL);
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51
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52 /* allocate memory */
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53 ocb = XMALLOC(sizeof(ocb_state));
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54 if (ocb == NULL) {
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55 return CRYPT_MEM;
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56 }
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57
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58 if ((err = ocb_init(ocb, cipher, key, keylen, nonce)) != CRYPT_OK) {
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59 goto LBL_ERR;
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60 }
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61
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62 while (ctlen > (unsigned long)ocb->block_len) {
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63 if ((err = ocb_decrypt(ocb, ct, pt)) != CRYPT_OK) {
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64 goto LBL_ERR;
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65 }
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66 ctlen -= ocb->block_len;
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67 pt += ocb->block_len;
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68 ct += ocb->block_len;
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69 }
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70
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71 err = ocb_done_decrypt(ocb, ct, ctlen, pt, tag, taglen, stat);
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72 LBL_ERR:
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73 #ifdef LTC_CLEAN_STACK
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74 zeromem(ocb, sizeof(ocb_state));
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75 #endif
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76
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77 XFREE(ocb);
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78
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79 return err;
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80 }
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81
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82 #endif