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/*
* libjingle
* Copyright 2014 Google Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
#define TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
// External libsrtp HMAC auth module which implements methods defined in
// auth_type_t.
// The default auth module will be replaced only when the ENABLE_EXTERNAL_AUTH
// flag is enabled. This allows us to access to authentication keys,
// as the default auth implementation doesn't provide access and avoids
// hashing each packet twice.
// How will libsrtp select this module?
// Libsrtp defines authentication function types identified by an unsigned
// integer, e.g. HMAC_SHA1 is 3. Using authentication ids, the application
// can plug any desired authentication modules into libsrtp.
// libsrtp also provides a mechanism to select different auth functions for
// individual streams. This can be done by setting the right value in
// the auth_type of srtp_policy_t. The application must first register auth
// functions and the corresponding authentication id using
// crypto_kernel_replace_auth_type function.
#if defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
#include "webrtc/base/basictypes.h"
extern "C" {
#ifdef SRTP_RELATIVE_PATH
#include "auth.h" // NOLINT
#else
#include "third_party/libsrtp/srtp/crypto/include/auth.h"
#endif // SRTP_RELATIVE_PATH
}
#define EXTERNAL_HMAC_SHA1 HMAC_SHA1 + 1
#define HMAC_KEY_LENGTH 20
// The HMAC context structure used to store authentication keys.
// The pointer to the key will be allocated in the external_hmac_init function.
// This pointer is owned by srtp_t in a template context.
typedef struct {
uint8_t key[HMAC_KEY_LENGTH];
int key_length;
} ExternalHmacContext;
err_status_t external_hmac_alloc(auth_t** a, int key_len, int out_len);
err_status_t external_hmac_dealloc(auth_t* a);
err_status_t external_hmac_init(ExternalHmacContext* state,
const uint8_t* key,
int key_len);
err_status_t external_hmac_start(ExternalHmacContext* state);
err_status_t external_hmac_update(ExternalHmacContext* state,
const uint8_t* message,
int msg_octets);
err_status_t external_hmac_compute(ExternalHmacContext* state,
const void* message,
int msg_octets,
int tag_len,
uint8_t* result);
err_status_t external_crypto_init();
#endif // defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
#endif // TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
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