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      1 /***************************************************************************
      2  *                                  _   _ ____  _
      3  *  Project                     ___| | | |  _ \| |
      4  *                             / __| | | | |_) | |
      5  *                            | (__| |_| |  _ <| |___
      6  *                             \___|\___/|_| \_\_____|
      7  *
      8  * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel (at) haxx.se>, et al.
      9  *
     10  * This software is licensed as described in the file COPYING, which
     11  * you should have received as part of this distribution. The terms
     12  * are also available at https://curl.haxx.se/docs/copyright.html.
     13  *
     14  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
     15  * copies of the Software, and permit persons to whom the Software is
     16  * furnished to do so, under the terms of the COPYING file.
     17  *
     18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
     19  * KIND, either express or implied.
     20  *
     21  * RFC2104 Keyed-Hashing for Message Authentication
     22  *
     23  ***************************************************************************/
     24 
     25 #include "curl_setup.h"
     26 
     27 #ifndef CURL_DISABLE_CRYPTO_AUTH
     28 
     29 #include <curl/curl.h>
     30 
     31 #include "curl_hmac.h"
     32 #include "curl_memory.h"
     33 
     34 /* The last #include file should be: */
     35 #include "memdebug.h"
     36 
     37 /*
     38  * Generic HMAC algorithm.
     39  *
     40  *   This module computes HMAC digests based on any hash function. Parameters
     41  * and computing procedures are set-up dynamically at HMAC computation
     42  * context initialisation.
     43  */
     44 
     45 static const unsigned char hmac_ipad = 0x36;
     46 static const unsigned char hmac_opad = 0x5C;
     47 
     48 
     49 
     50 HMAC_context *
     51 Curl_HMAC_init(const HMAC_params * hashparams,
     52                const unsigned char *key,
     53                unsigned int keylen)
     54 {
     55   size_t i;
     56   HMAC_context *ctxt;
     57   unsigned char *hkey;
     58   unsigned char b;
     59 
     60   /* Create HMAC context. */
     61   i = sizeof *ctxt + 2 * hashparams->hmac_ctxtsize +
     62     hashparams->hmac_resultlen;
     63   ctxt = malloc(i);
     64 
     65   if(!ctxt)
     66     return ctxt;
     67 
     68   ctxt->hmac_hash = hashparams;
     69   ctxt->hmac_hashctxt1 = (void *) (ctxt + 1);
     70   ctxt->hmac_hashctxt2 = (void *) ((char *) ctxt->hmac_hashctxt1 +
     71       hashparams->hmac_ctxtsize);
     72 
     73   /* If the key is too long, replace it by its hash digest. */
     74   if(keylen > hashparams->hmac_maxkeylen) {
     75     (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
     76     (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, key, keylen);
     77     hkey = (unsigned char *) ctxt->hmac_hashctxt2 + hashparams->hmac_ctxtsize;
     78     (*hashparams->hmac_hfinal)(hkey, ctxt->hmac_hashctxt1);
     79     key = hkey;
     80     keylen = hashparams->hmac_resultlen;
     81   }
     82 
     83   /* Prime the two hash contexts with the modified key. */
     84   (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
     85   (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt2);
     86 
     87   for(i = 0; i < keylen; i++) {
     88     b = (unsigned char)(*key ^ hmac_ipad);
     89     (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &b, 1);
     90     b = (unsigned char)(*key++ ^ hmac_opad);
     91     (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &b, 1);
     92   }
     93 
     94   for(; i < hashparams->hmac_maxkeylen; i++) {
     95     (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &hmac_ipad, 1);
     96     (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &hmac_opad, 1);
     97   }
     98 
     99   /* Done, return pointer to HMAC context. */
    100   return ctxt;
    101 }
    102 
    103 int Curl_HMAC_update(HMAC_context * ctxt,
    104                      const unsigned char *data,
    105                      unsigned int len)
    106 {
    107   /* Update first hash calculation. */
    108   (*ctxt->hmac_hash->hmac_hupdate)(ctxt->hmac_hashctxt1, data, len);
    109   return 0;
    110 }
    111 
    112 
    113 int Curl_HMAC_final(HMAC_context *ctxt, unsigned char *result)
    114 {
    115   const HMAC_params * hashparams = ctxt->hmac_hash;
    116 
    117   /* Do not get result if called with a null parameter: only release
    118      storage. */
    119 
    120   if(!result)
    121     result = (unsigned char *) ctxt->hmac_hashctxt2 +
    122      ctxt->hmac_hash->hmac_ctxtsize;
    123 
    124   (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt1);
    125   (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2,
    126    result, hashparams->hmac_resultlen);
    127   (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt2);
    128   free((char *) ctxt);
    129   return 0;
    130 }
    131 
    132 #endif /* CURL_DISABLE_CRYPTO_AUTH */
    133