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      1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
      2  *
      3  * LibTomCrypt is a library that provides various cryptographic
      4  * algorithms in a highly modular and flexible manner.
      5  *
      6  * The library is free for all purposes without any express
      7  * guarantee it works.
      8  *
      9  * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com
     10  */
     11 #include "tomcrypt.h"
     12 
     13 /**
     14   @file f9_done.c
     15   f9 Support, terminate the state
     16 */
     17 
     18 #ifdef LTC_F9_MODE
     19 
     20 /** Terminate the f9-MAC state
     21   @param f9     f9 state to terminate
     22   @param out      [out] Destination for the MAC tag
     23   @param outlen   [in/out] Destination size and final tag size
     24   Return CRYPT_OK on success
     25 */
     26 int f9_done(f9_state *f9, unsigned char *out, unsigned long *outlen)
     27 {
     28    int err, x;
     29    LTC_ARGCHK(f9 != NULL);
     30    LTC_ARGCHK(out  != NULL);
     31 
     32    /* check structure */
     33    if ((err = cipher_is_valid(f9->cipher)) != CRYPT_OK) {
     34       return err;
     35    }
     36 
     37    if ((f9->blocksize > cipher_descriptor[f9->cipher].block_length) || (f9->blocksize < 0) ||
     38        (f9->buflen > f9->blocksize) || (f9->buflen < 0)) {
     39       return CRYPT_INVALID_ARG;
     40    }
     41 
     42    if (f9->buflen != 0) {
     43       /* encrypt */
     44       cipher_descriptor[f9->cipher].ecb_encrypt(f9->IV, f9->IV, &f9->key);
     45       f9->buflen = 0;
     46       for (x = 0; x < f9->blocksize; x++) {
     47          f9->ACC[x] ^= f9->IV[x];
     48       }
     49    }
     50 
     51    /* schedule modified key */
     52    if ((err = cipher_descriptor[f9->cipher].setup(f9->akey, f9->keylen, 0, &f9->key)) != CRYPT_OK) {
     53       return err;
     54    }
     55 
     56    /* encrypt the ACC */
     57    cipher_descriptor[f9->cipher].ecb_encrypt(f9->ACC, f9->ACC, &f9->key);
     58    cipher_descriptor[f9->cipher].done(&f9->key);
     59 
     60    /* extract tag */
     61    for (x = 0; x < f9->blocksize && (unsigned long)x < *outlen; x++) {
     62       out[x] = f9->ACC[x];
     63    }
     64    *outlen = x;
     65 
     66 #ifdef LTC_CLEAN_STACK
     67    zeromem(f9, sizeof(*f9));
     68 #endif
     69    return CRYPT_OK;
     70 }
     71 
     72 #endif
     73 
     74 /* $Source: /cvs/libtom/libtomcrypt/src/mac/f9/f9_done.c,v $ */
     75 /* $Revision: 1.5 $ */
     76 /* $Date: 2006/11/09 01:53:32 $ */
     77 
     78