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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://libtomcrypt.com
*/
#include "tomcrypt.h"
/**
@file hmac_file.c
HMAC support, process a file, Tom St Denis/Dobes Vandermeer
*/
#ifdef LTC_HMAC
/**
HMAC a file
@param hash The index of the hash you wish to use
@param fname The name of the file you wish to HMAC
@param key The secret key
@param keylen The length of the secret key
@param out [out] The HMAC authentication tag
@param outlen [in/out] The max size and resulting size of the authentication tag
@return CRYPT_OK if successful, CRYPT_NOP if file support has been disabled
*/
int hmac_file(int hash, const char *fname,
const unsigned char *key, unsigned long keylen,
unsigned char *out, unsigned long *outlen)
{
#ifdef LTC_NO_FILE
return CRYPT_NOP;
#else
hmac_state hmac;
FILE *in;
unsigned char buf[512];
size_t x;
int err;
LTC_ARGCHK(fname != NULL);
LTC_ARGCHK(key != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
if((err = hash_is_valid(hash)) != CRYPT_OK) {
return err;
}
if ((err = hmac_init(&hmac, hash, key, keylen)) != CRYPT_OK) {
return err;
}
in = fopen(fname, "rb");
if (in == NULL) {
return CRYPT_FILE_NOTFOUND;
}
/* process the file contents */
do {
x = fread(buf, 1, sizeof(buf), in);
if ((err = hmac_process(&hmac, buf, (unsigned long)x)) != CRYPT_OK) {
/* we don't trap this error since we're already returning an error! */
fclose(in);
return err;
}
} while (x == sizeof(buf));
if (fclose(in) != 0) {
return CRYPT_ERROR;
}
/* get final hmac */
if ((err = hmac_done(&hmac, out, outlen)) != CRYPT_OK) {
return err;
}
#ifdef LTC_CLEAN_STACK
/* clear memory */
zeromem(buf, sizeof(buf));
#endif
return CRYPT_OK;
#endif
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/mac/hmac/hmac_file.c,v $ */
/* $Revision: 1.5 $ */
/* $Date: 2006/11/03 00:39:49 $ */
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