xref: /third_party/curl/lib/hmac.c (revision 13498266) 
1/***************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 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 https://curl.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 * SPDX-License-Identifier: curl
22 *
23 * RFC2104 Keyed-Hashing for Message Authentication
24 *
25 ***************************************************************************/
26
27#include "curl_setup.h"
28
29#if (defined(USE_CURL_NTLM_CORE) && !defined(USE_WINDOWS_SSPI))         \
30  || !defined(CURL_DISABLE_AWS) || !defined(CURL_DISABLE_DIGEST_AUTH)
31
32#include <curl/curl.h>
33
34#include "curl_hmac.h"
35#include "curl_memory.h"
36#include "warnless.h"
37
38/* The last #include file should be: */
39#include "memdebug.h"
40
41/*
42 * Generic HMAC algorithm.
43 *
44 *   This module computes HMAC digests based on any hash function. Parameters
45 * and computing procedures are set-up dynamically at HMAC computation context
46 * initialization.
47 */
48
49static const unsigned char hmac_ipad = 0x36;
50static const unsigned char hmac_opad = 0x5C;
51
52
53
54struct HMAC_context *
55Curl_HMAC_init(const struct HMAC_params *hashparams,
56               const unsigned char *key,
57               unsigned int keylen)
58{
59  size_t i;
60  struct HMAC_context *ctxt;
61  unsigned char *hkey;
62  unsigned char b;
63
64  /* Create HMAC context. */
65  i = sizeof(*ctxt) + 2 * hashparams->hmac_ctxtsize +
66    hashparams->hmac_resultlen;
67  ctxt = malloc(i);
68
69  if(!ctxt)
70    return ctxt;
71
72  ctxt->hmac_hash = hashparams;
73  ctxt->hmac_hashctxt1 = (void *) (ctxt + 1);
74  ctxt->hmac_hashctxt2 = (void *) ((char *) ctxt->hmac_hashctxt1 +
75      hashparams->hmac_ctxtsize);
76
77  /* If the key is too long, replace it by its hash digest. */
78  if(keylen > hashparams->hmac_maxkeylen) {
79    (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
80    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, key, keylen);
81    hkey = (unsigned char *) ctxt->hmac_hashctxt2 + hashparams->hmac_ctxtsize;
82    (*hashparams->hmac_hfinal)(hkey, ctxt->hmac_hashctxt1);
83    key = hkey;
84    keylen = hashparams->hmac_resultlen;
85  }
86
87  /* Prime the two hash contexts with the modified key. */
88  (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);
89  (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt2);
90
91  for(i = 0; i < keylen; i++) {
92    b = (unsigned char)(*key ^ hmac_ipad);
93    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &b, 1);
94    b = (unsigned char)(*key++ ^ hmac_opad);
95    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &b, 1);
96  }
97
98  for(; i < hashparams->hmac_maxkeylen; i++) {
99    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &hmac_ipad, 1);
100    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &hmac_opad, 1);
101  }
102
103  /* Done, return pointer to HMAC context. */
104  return ctxt;
105}
106
107int Curl_HMAC_update(struct HMAC_context *ctxt,
108                     const unsigned char *data,
109                     unsigned int len)
110{
111  /* Update first hash calculation. */
112  (*ctxt->hmac_hash->hmac_hupdate)(ctxt->hmac_hashctxt1, data, len);
113  return 0;
114}
115
116
117int Curl_HMAC_final(struct HMAC_context *ctxt, unsigned char *result)
118{
119  const struct HMAC_params *hashparams = ctxt->hmac_hash;
120
121  /* Do not get result if called with a null parameter: only release
122     storage. */
123
124  if(!result)
125    result = (unsigned char *) ctxt->hmac_hashctxt2 +
126     ctxt->hmac_hash->hmac_ctxtsize;
127
128  (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt1);
129  (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2,
130   result, hashparams->hmac_resultlen);
131  (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt2);
132  free((char *) ctxt);
133  return 0;
134}
135
136/*
137 * Curl_hmacit()
138 *
139 * This is used to generate a HMAC hash, for the specified input data, given
140 * the specified hash function and key.
141 *
142 * Parameters:
143 *
144 * hashparams [in]     - The hash function (Curl_HMAC_MD5).
145 * key        [in]     - The key to use.
146 * keylen     [in]     - The length of the key.
147 * data       [in]     - The data to encrypt.
148 * datalen    [in]     - The length of the data.
149 * output     [in/out] - The output buffer.
150 *
151 * Returns CURLE_OK on success.
152 */
153CURLcode Curl_hmacit(const struct HMAC_params *hashparams,
154                     const unsigned char *key, const size_t keylen,
155                     const unsigned char *data, const size_t datalen,
156                     unsigned char *output)
157{
158  struct HMAC_context *ctxt =
159    Curl_HMAC_init(hashparams, key, curlx_uztoui(keylen));
160
161  if(!ctxt)
162    return CURLE_OUT_OF_MEMORY;
163
164  /* Update the digest with the given challenge */
165  Curl_HMAC_update(ctxt, data, curlx_uztoui(datalen));
166
167  /* Finalise the digest */
168  Curl_HMAC_final(ctxt, output);
169
170  return CURLE_OK;
171}
172
173#endif /* Using NTLM (without SSPI) or AWS */
174