1/***************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2011, 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
31#define _MPRINTF_REPLACE /* use our functions only */
32#include <curl/mprintf.h>
33
34#include "curl_memory.h"
35/* The last #include file should be: */
36#include "memdebug.h"
37
38/*
39 * Generic HMAC algorithm.
40 *
41 *   This module computes HMAC digests based on any hash function. Parameters
42 * and computing procedures are set-up dynamically at HMAC computation
43 * context initialisation.
44 */
45
46static const unsigned char hmac_ipad = 0x36;
47static const unsigned char hmac_opad = 0x5C;
48
49
50
51HMAC_context *
52Curl_HMAC_init(const HMAC_params * hashparams,
53               const unsigned char * key,
54               unsigned int keylen)
55{
56  size_t i;
57  HMAC_context * ctxt;
58  unsigned char * hkey;
59  unsigned char b;
60
61  /* Create HMAC context. */
62  i = sizeof *ctxt + 2 * hashparams->hmac_ctxtsize +
63    hashparams->hmac_resultlen;
64  ctxt = malloc(i);
65
66  if(!ctxt)
67    return ctxt;
68
69  ctxt->hmac_hash = hashparams;
70  ctxt->hmac_hashctxt1 = (void *) (ctxt + 1);
71  ctxt->hmac_hashctxt2 = (void *) ((char *) ctxt->hmac_hashctxt1 +
72      hashparams->hmac_ctxtsize);
73
74  /* If the key is too long, replace it by its hash digest. */
75  if(keylen > hashparams->hmac_maxkeylen) {
76    (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
77    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, key, keylen);
78    hkey = (unsigned char *) ctxt->hmac_hashctxt2 + hashparams->hmac_ctxtsize;
79    (*hashparams->hmac_hfinal)(hkey, ctxt->hmac_hashctxt1);
80    key = hkey;
81    keylen = hashparams->hmac_resultlen;
82  }
83
84  /* Prime the two hash contexts with the modified key. */
85  (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
86  (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt2);
87
88  for(i = 0; i < keylen; i++) {
89    b = (unsigned char)(*key ^ hmac_ipad);
90    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &b, 1);
91    b = (unsigned char)(*key++ ^ hmac_opad);
92    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &b, 1);
93  }
94
95  for(; i < hashparams->hmac_maxkeylen; i++) {
96    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &hmac_ipad, 1);
97    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &hmac_opad, 1);
98  }
99
100  /* Done, return pointer to HMAC context. */
101  return ctxt;
102}
103
104int Curl_HMAC_update(HMAC_context * ctxt,
105                     const unsigned char * data,
106                     unsigned int len)
107{
108  /* Update first hash calculation. */
109  (*ctxt->hmac_hash->hmac_hupdate)(ctxt->hmac_hashctxt1, data, len);
110  return 0;
111}
112
113
114int Curl_HMAC_final(HMAC_context * ctxt, unsigned char * result)
115{
116  const HMAC_params * hashparams = ctxt->hmac_hash;
117
118  /* Do not get result if called with a null parameter: only release
119     storage. */
120
121  if(!result)
122    result = (unsigned char *) ctxt->hmac_hashctxt2 +
123     ctxt->hmac_hash->hmac_ctxtsize;
124
125  (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt1);
126  (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2,
127   result, hashparams->hmac_resultlen);
128  (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt2);
129  free((char *) ctxt);
130  return 0;
131}
132
133#endif /* CURL_DISABLE_CRYPTO_AUTH */
134