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ocb_encrypt_authenticate_memory.c
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 *
 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
 */

/** 
  @file ocb_encrypt_authenticate_memory.c
  OCB implementation, encrypt block of memory, by Tom St Denis
*/
#include "tomcrypt.h"

#ifdef LTC_OCB_MODE

/**
   Encrypt and generate an authentication code for a buffer of memory
   @param cipher     The index of the cipher desired
   @param key        The secret key
   @param keylen     The length of the secret key (octets)
   @param nonce      The session nonce (length of the block ciphers block size)
   @param pt         The plaintext
   @param ptlen      The length of the plaintext (octets)
   @param ct         [out] The ciphertext
   @param tag        [out] The authentication tag
   @param taglen     [in/out] The max size and resulting size of the authentication tag
   @return CRYPT_OK if successful
*/
int ocb_encrypt_authenticate_memory(int cipher,
    const unsigned char *key,    unsigned long keylen,
    const unsigned char *nonce,  
    const unsigned char *pt,     unsigned long ptlen,
          unsigned char *ct,
          unsigned char *tag,    unsigned long *taglen)
{
   int err;
   ocb_state *ocb;

   LTC_ARGCHK(key    != NULL);
   LTC_ARGCHK(nonce  != NULL);
   LTC_ARGCHK(pt     != NULL);
   LTC_ARGCHK(ct     != NULL);
   LTC_ARGCHK(tag    != NULL);
   LTC_ARGCHK(taglen != NULL);

   /* allocate ram */
   ocb = XMALLOC(sizeof(ocb_state));
   if (ocb == NULL) {
      return CRYPT_MEM;
   }

   if ((err = ocb_init(ocb, cipher, key, keylen, nonce)) != CRYPT_OK) {
      goto LBL_ERR;
   }

   while (ptlen > (unsigned long)ocb->block_len) {
        if ((err = ocb_encrypt(ocb, pt, ct)) != CRYPT_OK) {
           goto LBL_ERR;
        }
        ptlen   -= ocb->block_len;
        pt      += ocb->block_len;
        ct      += ocb->block_len;
   }

   err = ocb_done_encrypt(ocb, pt, ptlen, ct, tag, taglen);
LBL_ERR:
#ifdef LTC_CLEAN_STACK
   zeromem(ocb, sizeof(ocb_state));
#endif

   XFREE(ocb);

   return err;
}

#endif

/* $Source: /cvs/libtom/libtomcrypt/src/encauth/ocb/ocb_encrypt_authenticate_memory.c,v $ */
/* $Revision: 1.6 $ */
/* $Date: 2007/05/12 14:32:35 $ */

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