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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 
49 static const unsigned char hmac_ipad = 0x36;
50 static const unsigned char hmac_opad = 0x5C;
51 
52 
53 
54 struct HMAC_context *
Curl_HMAC_init(const struct HMAC_params * hashparams,const unsigned char * key,unsigned int keylen)55 Curl_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 
Curl_HMAC_update(struct HMAC_context * ctxt,const unsigned char * data,unsigned int len)107 int 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 
Curl_HMAC_final(struct HMAC_context * ctxt,unsigned char * result)117 int 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  */
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)153 CURLcode 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