1/*
2 * libjingle
3 * Copyright 2014 Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 *  1. Redistributions of source code must retain the above copyright notice,
9 *     this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright notice,
11 *     this list of conditions and the following disclaimer in the documentation
12 *     and/or other materials provided with the distribution.
13 *  3. The name of the author may not be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#ifndef TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
29#define TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
30
31// External libsrtp HMAC auth module which implements methods defined in
32// auth_type_t.
33// The default auth module will be replaced only when the ENABLE_EXTERNAL_AUTH
34// flag is enabled. This allows us to access to authentication keys,
35// as the default auth implementation doesn't provide access and avoids
36// hashing each packet twice.
37
38// How will libsrtp select this module?
39// Libsrtp defines authentication function types identified by an unsigned
40// integer, e.g. HMAC_SHA1 is 3. Using authentication ids, the application
41// can plug any desired authentication modules into libsrtp.
42// libsrtp also provides a mechanism to select different auth functions for
43// individual streams. This can be done by setting the right value in
44// the auth_type of srtp_policy_t. The application must first register auth
45// functions and the corresponding authentication id using
46// crypto_kernel_replace_auth_type function.
47#if defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
48
49#include "webrtc/base/basictypes.h"
50#ifdef SRTP_RELATIVE_PATH
51#include "auth.h"  // NOLINT
52#else
53#include "third_party/libsrtp/crypto/include/auth.h"
54#endif  // SRTP_RELATIVE_PATH
55
56#define EXTERNAL_HMAC_SHA1 HMAC_SHA1 + 1
57#define HMAC_KEY_LENGTH 20
58
59// The HMAC context structure used to store authentication keys.
60// The pointer to the key  will be allocated in the external_hmac_init function.
61// This pointer is owned by srtp_t in a template context.
62typedef struct {
63  uint8 key[HMAC_KEY_LENGTH];
64  int key_length;
65} external_hmac_ctx_t;
66
67err_status_t external_hmac_alloc(auth_t** a, int key_len, int out_len);
68
69err_status_t external_hmac_dealloc(auth_t* a);
70
71err_status_t external_hmac_init(external_hmac_ctx_t* state,
72                                const uint8_t* key,
73                                int key_len);
74
75err_status_t external_hmac_start(external_hmac_ctx_t* state);
76
77err_status_t external_hmac_update(external_hmac_ctx_t* state,
78                                  const uint8_t* message,
79                                  int msg_octets);
80
81err_status_t external_hmac_compute(external_hmac_ctx_t* state,
82                                   const void* message,
83                                   int msg_octets,
84                                   int tag_len,
85                                   uint8_t* result);
86
87err_status_t external_crypto_init();
88
89#endif  // defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
90#endif  // TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
91