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1 /***************************************************************************
2  *                                  _   _ ____  _
3  *  Project                     ___| | | |  _ \| |
4  *                             / __| | | | |_) | |
5  *                            | (__| |_| |  _ <| |___
6  *                             \___|\___/|_| \_\_____|
7  *
8  * Copyright (C) 1998 - 2018, 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.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 *
Curl_HMAC_init(const HMAC_params * hashparams,const unsigned char * key,unsigned int keylen)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 
Curl_HMAC_update(HMAC_context * ctxt,const unsigned char * data,unsigned int len)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 
Curl_HMAC_final(HMAC_context * ctxt,unsigned char * result)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