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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 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 https://curl.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.
*
* SPDX-License-Identifier: curl
*
* RFC2104 Keyed-Hashing for Message Authentication
*
***************************************************************************/
#include "curl_setup.h"
#ifndef CURL_DISABLE_CRYPTO_AUTH
#include <curl/curl.h>
#include "curl_hmac.h"
#include "curl_memory.h"
#include "warnless.h"
/* The last #include file should be: */
#include "memdebug.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
* initialization.
*/
static const unsigned char hmac_ipad = 0x36;
static const unsigned char hmac_opad = 0x5C;
struct HMAC_context *
Curl_HMAC_init(const struct HMAC_params *hashparams,
const unsigned char *key,
unsigned int keylen)
{
size_t i;
struct HMAC_context *ctxt;
unsigned char *hkey;
unsigned char b;
/* Create HMAC context. */
i = sizeof(*ctxt) + 2 * hashparams->hmac_ctxtsize +
hashparams->hmac_resultlen;
ctxt = 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 = (unsigned char)(*key ^ hmac_ipad);
(*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &b, 1);
b = (unsigned char)(*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(struct 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(struct HMAC_context *ctxt, unsigned char *result)
{
const struct 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;
}
/*
* Curl_hmacit()
*
* This is used to generate a HMAC hash, for the specified input data, given
* the specified hash function and key.
*
* Parameters:
*
* hashparams [in] - The hash function (Curl_HMAC_MD5).
* key [in] - The key to use.
* keylen [in] - The length of the key.
* data [in] - The data to encrypt.
* datalen [in] - The length of the data.
* output [in/out] - The output buffer.
*
* Returns CURLE_OK on success.
*/
CURLcode Curl_hmacit(const struct HMAC_params *hashparams,
const unsigned char *key, const size_t keylen,
const unsigned char *data, const size_t datalen,
unsigned char *output)
{
struct HMAC_context *ctxt =
Curl_HMAC_init(hashparams, key, curlx_uztoui(keylen));
if(!ctxt)
return CURLE_OUT_OF_MEMORY;
/* Update the digest with the given challenge */
Curl_HMAC_update(ctxt, data, curlx_uztoui(datalen));
/* Finalise the digest */
Curl_HMAC_final(ctxt, output);
return CURLE_OK;
}
#endif /* CURL_DISABLE_CRYPTO_AUTH */
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