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/*
* Copyright 2014 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "pc/external_hmac.h"
#include <stdlib.h> // For malloc/free.
#include <string.h>
#include <cstdint>
#include "rtc_base/logging.h"
#include "rtc_base/zero_memory.h"
#include "third_party/libsrtp/crypto/include/auth.h"
#include "third_party/libsrtp/include/srtp.h"
// Begin test case 0 */
static const uint8_t kExternalHmacTestCase0Key[20] = {
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b};
static const uint8_t kExternalHmacTestCase0Data[8] = {
0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65 // "Hi There"
};
static const uint8_t kExternalHmacFakeTag[10] = {0xba, 0xdd, 0xba, 0xdd, 0xba,
0xdd, 0xba, 0xdd, 0xba, 0xdd};
static const srtp_auth_test_case_t kExternalHmacTestCase0 = {
20, // Octets in key
const_cast<uint8_t*>(kExternalHmacTestCase0Key), // Key
8, // Octets in data
const_cast<uint8_t*>(kExternalHmacTestCase0Data), // Data
10, // Octets in tag
const_cast<uint8_t*>(kExternalHmacFakeTag), // Tag
nullptr // Pointer to next
// testcase
};
static const char kExternalHmacDescription[] =
"external hmac sha-1 authentication";
// srtp_auth_type_t external_hmac is the hmac metaobject
static const srtp_auth_type_t external_hmac = {
external_hmac_alloc,
external_hmac_dealloc,
external_hmac_init,
external_hmac_compute,
external_hmac_update,
external_hmac_start,
const_cast<char*>(kExternalHmacDescription),
const_cast<srtp_auth_test_case_t*>(&kExternalHmacTestCase0),
EXTERNAL_HMAC_SHA1};
srtp_err_status_t external_hmac_alloc(srtp_auth_t** a,
int key_len,
int out_len) {
uint8_t* pointer;
// Check key length - note that we don't support keys larger
// than 20 bytes yet
if (key_len > 20)
return srtp_err_status_bad_param;
// Check output length - should be less than 20 bytes/
if (out_len > 20)
return srtp_err_status_bad_param;
// Allocate memory for auth and hmac_ctx_t structures.
pointer = new uint8_t[(sizeof(ExternalHmacContext) + sizeof(srtp_auth_t))];
if (pointer == nullptr)
return srtp_err_status_alloc_fail;
// Set pointers
*a = reinterpret_cast<srtp_auth_t*>(pointer);
// `external_hmac` is const and libsrtp expects `type` to be non-const.
// const conversion is required. `external_hmac` is constant because we don't
// want to increase global count in Chrome.
(*a)->type = const_cast<srtp_auth_type_t*>(&external_hmac);
(*a)->state = pointer + sizeof(srtp_auth_t);
(*a)->out_len = out_len;
(*a)->key_len = key_len;
(*a)->prefix_len = 0;
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_dealloc(srtp_auth_t* a) {
webrtc::ExplicitZeroMemory(a,
sizeof(ExternalHmacContext) + sizeof(srtp_auth_t));
// Free memory
delete[] a;
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_init(void* state,
const uint8_t* key,
int key_len) {
if (key_len > HMAC_KEY_LENGTH)
return srtp_err_status_bad_param;
ExternalHmacContext* context = static_cast<ExternalHmacContext*>(state);
memcpy(context->key, key, key_len);
context->key_length = key_len;
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_start(void* /*state*/) {
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_update(void* /*state*/,
const uint8_t* /*message*/,
int /*msg_octets*/) {
return srtp_err_status_ok;
}
srtp_err_status_t external_hmac_compute(void* /*state*/,
const uint8_t* /*message*/,
int /*msg_octets*/,
int tag_len,
uint8_t* result) {
memcpy(result, kExternalHmacFakeTag, tag_len);
return srtp_err_status_ok;
}
srtp_err_status_t external_crypto_init() {
// `external_hmac` is const. const_cast is required as libsrtp expects
// non-const.
srtp_err_status_t status = srtp_replace_auth_type(
const_cast<srtp_auth_type_t*>(&external_hmac), EXTERNAL_HMAC_SHA1);
if (status) {
RTC_LOG(LS_ERROR) << "Error in replacing default auth module, error: "
<< status;
return srtp_err_status_fail;
}
return srtp_err_status_ok;
}
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