1 /*
2 * Copyright 2014 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "pc/external_hmac.h"
12
13 #include <stdlib.h> // For malloc/free.
14 #include <string.h>
15
16 #include "rtc_base/logging.h"
17 #include "rtc_base/zero_memory.h"
18 #include "third_party/libsrtp/include/srtp.h"
19
20 // Begin test case 0 */
21 static const uint8_t kExternalHmacTestCase0Key[20] = {
22 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
23 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b};
24
25 static const uint8_t kExternalHmacTestCase0Data[8] = {
26 0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65 // "Hi There"
27 };
28
29 static const uint8_t kExternalHmacFakeTag[10] = {0xba, 0xdd, 0xba, 0xdd, 0xba,
30 0xdd, 0xba, 0xdd, 0xba, 0xdd};
31
32 static const srtp_auth_test_case_t kExternalHmacTestCase0 = {
33 20, // Octets in key
34 const_cast<uint8_t*>(kExternalHmacTestCase0Key), // Key
35 8, // Octets in data
36 const_cast<uint8_t*>(kExternalHmacTestCase0Data), // Data
37 10, // Octets in tag
38 const_cast<uint8_t*>(kExternalHmacFakeTag), // Tag
39 NULL // Pointer to next
40 // testcase
41 };
42
43 static const char kExternalHmacDescription[] =
44 "external hmac sha-1 authentication";
45
46 // srtp_auth_type_t external_hmac is the hmac metaobject
47
48 static const srtp_auth_type_t external_hmac = {
49 external_hmac_alloc,
50 external_hmac_dealloc,
51 external_hmac_init,
52 external_hmac_compute,
53 external_hmac_update,
54 external_hmac_start,
55 const_cast<char*>(kExternalHmacDescription),
56 const_cast<srtp_auth_test_case_t*>(&kExternalHmacTestCase0),
57 EXTERNAL_HMAC_SHA1};
58
external_hmac_alloc(srtp_auth_t ** a,int key_len,int out_len)59 srtp_err_status_t external_hmac_alloc(srtp_auth_t** a,
60 int key_len,
61 int out_len) {
62 uint8_t* pointer;
63
64 // Check key length - note that we don't support keys larger
65 // than 20 bytes yet
66 if (key_len > 20)
67 return srtp_err_status_bad_param;
68
69 // Check output length - should be less than 20 bytes/
70 if (out_len > 20)
71 return srtp_err_status_bad_param;
72
73 // Allocate memory for auth and hmac_ctx_t structures.
74 pointer = new uint8_t[(sizeof(ExternalHmacContext) + sizeof(srtp_auth_t))];
75 if (pointer == NULL)
76 return srtp_err_status_alloc_fail;
77
78 // Set pointers
79 *a = reinterpret_cast<srtp_auth_t*>(pointer);
80 // |external_hmac| is const and libsrtp expects |type| to be non-const.
81 // const conversion is required. |external_hmac| is constant because we don't
82 // want to increase global count in Chrome.
83 (*a)->type = const_cast<srtp_auth_type_t*>(&external_hmac);
84 (*a)->state = pointer + sizeof(srtp_auth_t);
85 (*a)->out_len = out_len;
86 (*a)->key_len = key_len;
87 (*a)->prefix_len = 0;
88
89 return srtp_err_status_ok;
90 }
91
external_hmac_dealloc(srtp_auth_t * a)92 srtp_err_status_t external_hmac_dealloc(srtp_auth_t* a) {
93 rtc::ExplicitZeroMemory(a, sizeof(ExternalHmacContext) + sizeof(srtp_auth_t));
94
95 // Free memory
96 delete[] a;
97
98 return srtp_err_status_ok;
99 }
100
external_hmac_init(void * state,const uint8_t * key,int key_len)101 srtp_err_status_t external_hmac_init(void* state,
102 const uint8_t* key,
103 int key_len) {
104 if (key_len > HMAC_KEY_LENGTH)
105 return srtp_err_status_bad_param;
106
107 ExternalHmacContext* context = static_cast<ExternalHmacContext*>(state);
108 memcpy(context->key, key, key_len);
109 context->key_length = key_len;
110 return srtp_err_status_ok;
111 }
112
external_hmac_start(void *)113 srtp_err_status_t external_hmac_start(void* /*state*/) {
114 return srtp_err_status_ok;
115 }
116
external_hmac_update(void *,const uint8_t *,int)117 srtp_err_status_t external_hmac_update(void* /*state*/,
118 const uint8_t* /*message*/,
119 int /*msg_octets*/) {
120 return srtp_err_status_ok;
121 }
122
external_hmac_compute(void *,const uint8_t *,int,int tag_len,uint8_t * result)123 srtp_err_status_t external_hmac_compute(void* /*state*/,
124 const uint8_t* /*message*/,
125 int /*msg_octets*/,
126 int tag_len,
127 uint8_t* result) {
128 memcpy(result, kExternalHmacFakeTag, tag_len);
129 return srtp_err_status_ok;
130 }
131
external_crypto_init()132 srtp_err_status_t external_crypto_init() {
133 // |external_hmac| is const. const_cast is required as libsrtp expects
134 // non-const.
135 srtp_err_status_t status = srtp_replace_auth_type(
136 const_cast<srtp_auth_type_t*>(&external_hmac), EXTERNAL_HMAC_SHA1);
137 if (status) {
138 RTC_LOG(LS_ERROR) << "Error in replacing default auth module, error: "
139 << status;
140 return srtp_err_status_fail;
141 }
142 return srtp_err_status_ok;
143 }
144