1/***************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@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 http://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_hmac.h"
30#include "curl_memory.h"
31/* The last #include file should be: */
32#include "memdebug.h"
33
34/*
35 * Generic HMAC algorithm.
36 *
37 *   This module computes HMAC digests based on any hash function. Parameters
38 * and computing procedures are set-up dynamically at HMAC computation
39 * context initialisation.
40 */
41
42static const unsigned char hmac_ipad = 0x36;
43static const unsigned char hmac_opad = 0x5C;
44
45
46
47HMAC_context *
48Curl_HMAC_init(const HMAC_params * hashparams,
49               const unsigned char * key,
50               unsigned int keylen)
51{
52  size_t i;
53  HMAC_context * ctxt;
54  unsigned char * hkey;
55  unsigned char b;
56
57  /* Create HMAC context. */
58  i = sizeof *ctxt + 2 * hashparams->hmac_ctxtsize +
59    hashparams->hmac_resultlen;
60  ctxt = malloc(i);
61
62  if(!ctxt)
63    return ctxt;
64
65  ctxt->hmac_hash = hashparams;
66  ctxt->hmac_hashctxt1 = (void *) (ctxt + 1);
67  ctxt->hmac_hashctxt2 = (void *) ((char *) ctxt->hmac_hashctxt1 +
68      hashparams->hmac_ctxtsize);
69
70  /* If the key is too long, replace it by its hash digest. */
71  if(keylen > hashparams->hmac_maxkeylen) {
72    (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
73    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, key, keylen);
74    hkey = (unsigned char *) ctxt->hmac_hashctxt2 + hashparams->hmac_ctxtsize;
75    (*hashparams->hmac_hfinal)(hkey, ctxt->hmac_hashctxt1);
76    key = hkey;
77    keylen = hashparams->hmac_resultlen;
78  }
79
80  /* Prime the two hash contexts with the modified key. */
81  (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
82  (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt2);
83
84  for(i = 0; i < keylen; i++) {
85    b = (unsigned char)(*key ^ hmac_ipad);
86    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &b, 1);
87    b = (unsigned char)(*key++ ^ hmac_opad);
88    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &b, 1);
89  }
90
91  for(; i < hashparams->hmac_maxkeylen; i++) {
92    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &hmac_ipad, 1);
93    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &hmac_opad, 1);
94  }
95
96  /* Done, return pointer to HMAC context. */
97  return ctxt;
98}
99
100int Curl_HMAC_update(HMAC_context * ctxt,
101                     const unsigned char * data,
102                     unsigned int len)
103{
104  /* Update first hash calculation. */
105  (*ctxt->hmac_hash->hmac_hupdate)(ctxt->hmac_hashctxt1, data, len);
106  return 0;
107}
108
109
110int Curl_HMAC_final(HMAC_context * ctxt, unsigned char * result)
111{
112  const HMAC_params * hashparams = ctxt->hmac_hash;
113
114  /* Do not get result if called with a null parameter: only release
115     storage. */
116
117  if(!result)
118    result = (unsigned char *) ctxt->hmac_hashctxt2 +
119     ctxt->hmac_hash->hmac_ctxtsize;
120
121  (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt1);
122  (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2,
123   result, hashparams->hmac_resultlen);
124  (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt2);
125  free((char *) ctxt);
126  return 0;
127}
128
129#endif /* CURL_DISABLE_CRYPTO_AUTH */
130