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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_done.c
HMAC support, terminate stream, Tom St Denis/Dobes Vandermeer
*/
#ifdef LTC_HMAC
#define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize
/**
Terminate an HMAC session
@param hmac The HMAC state
@param out [out] The destination of the HMAC authentication tag
@param outlen [in/out] The max size and resulting size of the HMAC authentication tag
@return CRYPT_OK if successful
*/
int hmac_done(hmac_state *hmac, unsigned char *out, unsigned long *outlen)
{
unsigned char buf[MAXBLOCKSIZE], isha[MAXBLOCKSIZE];
unsigned long hashsize, i;
int hash, err;
LTC_ARGCHK(hmac != NULL);
LTC_ARGCHK(out != NULL);
/* test hash */
hash = hmac->hash;
if((err = hash_is_valid(hash)) != CRYPT_OK) {
return err;
}
/* get the hash message digest size */
hashsize = hash_descriptor[hash].hashsize;
/* Get the hash of the first HMAC vector plus the data */
if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) {
goto LBL_ERR;
}
/* Create the second HMAC vector vector for step (3) */
for(i=0; i < HMAC_BLOCKSIZE; i++) {
buf[i] = hmac->key[i] ^ 0x5C;
}
/* Now calculate the "outer" hash for step (5), (6), and (7) */
if ((err = hash_descriptor[hash].init(&hmac->md)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = hash_descriptor[hash].process(&hmac->md, isha, hashsize)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = hash_descriptor[hash].done(&hmac->md, buf)) != CRYPT_OK) {
goto LBL_ERR;
}
/* copy to output */
for (i = 0; i < hashsize && i < *outlen; i++) {
out[i] = buf[i];
}
*outlen = i;
err = CRYPT_OK;
LBL_ERR:
XFREE(hmac->key);
#ifdef LTC_CLEAN_STACK
zeromem(isha, hashsize);
zeromem(buf, hashsize);
zeromem(hmac, sizeof(*hmac));
#endif
return err;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/mac/hmac/hmac_done.c,v $ */
/* $Revision: 1.5 $ */
/* $Date: 2006/11/03 00:39:49 $ */
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