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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2010, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* RFC2104 Keyed-Hashing for Message Authentication
*
***************************************************************************/
#include "setup.h"
#ifndef CURL_DISABLE_CRYPTO_AUTH
#include "curl_hmac.h"
/*
* Generic HMAC algorithm.
*
* This module computes HMAC digests based on any hash function. Parameters
* and computing procedures are set-up dynamically at HMAC computation
* context initialisation.
*/
static const unsigned char hmac_ipad = 0x36;
static const unsigned char hmac_opad = 0x5C;
HMAC_context *
Curl_HMAC_init(const HMAC_params * hashparams,
const unsigned char * key,
unsigned int keylen)
{
unsigned int i;
HMAC_context * ctxt;
unsigned char * hkey;
unsigned char b;
/* Create HMAC context. */
i = sizeof *ctxt + 2 * hashparams->hmac_ctxtsize + hashparams->hmac_resultlen;
ctxt = (HMAC_context *) malloc(i);
if(!ctxt)
return ctxt;
ctxt->hmac_hash = hashparams;
ctxt->hmac_hashctxt1 = (void *) (ctxt + 1);
ctxt->hmac_hashctxt2 = (void *) ((char *) ctxt->hmac_hashctxt1 +
hashparams->hmac_ctxtsize);
/* If the key is too long, replace it by its hash digest. */
if(keylen > hashparams->hmac_maxkeylen) {
(*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
(*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, key, keylen);
hkey = (unsigned char *) ctxt->hmac_hashctxt2 + hashparams->hmac_ctxtsize;
(*hashparams->hmac_hfinal)(hkey, ctxt->hmac_hashctxt1);
key = hkey;
keylen = hashparams->hmac_resultlen;
}
/* Prime the two hash contexts with the modified key. */
(*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
(*hashparams->hmac_hinit)(ctxt->hmac_hashctxt2);
for (i = 0; i < keylen; i++) {
b = *key ^ hmac_ipad;
(*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &b, 1);
b = *key++ ^ hmac_opad;
(*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &b, 1);
}
for (; i < hashparams->hmac_maxkeylen; i++) {
(*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &hmac_ipad, 1);
(*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &hmac_opad, 1);
}
/* Done, return pointer to HMAC context. */
return ctxt;
}
int Curl_HMAC_update(HMAC_context * ctxt,
const unsigned char * data,
unsigned int len)
{
/* Update first hash calculation. */
(*ctxt->hmac_hash->hmac_hupdate)(ctxt->hmac_hashctxt1, data, len);
return 0;
}
int Curl_HMAC_final(HMAC_context * ctxt, unsigned char * result)
{
const HMAC_params * hashparams = ctxt->hmac_hash;
/* Do not get result if called with a null parameter: only release storage. */
if(!result)
result = (unsigned char *) ctxt->hmac_hashctxt2 +
ctxt->hmac_hash->hmac_ctxtsize;
(*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt1);
(*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2,
result, hashparams->hmac_resultlen);
(*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt2);
free((char *) ctxt);
return 0;
}
#endif /* CURL_DISABLE_CRYPTO_AUTH */
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