blob: 9def64c6b4d4e6766c8a9d33c23a2a68a2e1d933 [file] [log] [blame]
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "media/cast/common/transport_encryption_handler.h"
#include <stddef.h>
#include <memory>
#include "base/logging.h"
#include "base/notreached.h"
#include "crypto/encryptor.h"
#include "crypto/symmetric_key.h"
namespace media {
namespace cast {
namespace {
// Crypto.
const size_t kAesBlockSize = 16;
const size_t kAesKeySize = 16;
std::string GetAesNonce(FrameId frame_id, const std::string& iv_mask) {
DCHECK(!frame_id.is_null());
std::string aes_nonce(kAesBlockSize, 0);
// Serializing frame_id in big-endian order (aes_nonce[8] is the most
// significant byte of frame_id).
const uint32_t truncated_id = frame_id.lower_32_bits();
aes_nonce[11] = truncated_id & 0xff;
aes_nonce[10] = (truncated_id >> 8) & 0xff;
aes_nonce[9] = (truncated_id >> 16) & 0xff;
aes_nonce[8] = (truncated_id >> 24) & 0xff;
for (size_t i = 0; i < kAesBlockSize; ++i) {
aes_nonce[i] ^= iv_mask[i];
}
return aes_nonce;
}
} // namespace
TransportEncryptionHandler::TransportEncryptionHandler()
: key_(), encryptor_(), iv_mask_(), is_activated_(false) {}
TransportEncryptionHandler::~TransportEncryptionHandler() = default;
bool TransportEncryptionHandler::Initialize(const std::string& aes_key,
const std::string& aes_iv_mask) {
is_activated_ = false;
if (aes_iv_mask.size() == kAesKeySize && aes_key.size() == kAesKeySize) {
iv_mask_ = aes_iv_mask;
key_ = crypto::SymmetricKey::Import(crypto::SymmetricKey::AES, aes_key);
encryptor_ = std::make_unique<crypto::Encryptor>();
encryptor_->Init(key_.get(), crypto::Encryptor::CTR, std::string());
is_activated_ = true;
} else if (aes_iv_mask.size() != 0 || aes_key.size() != 0) {
DCHECK_EQ(aes_iv_mask.size(), 0u)
<< "Invalid Crypto configuration: aes_iv_mask.size";
DCHECK_EQ(aes_key.size(), 0u)
<< "Invalid Crypto configuration: aes_key.size";
return false;
}
return true;
}
bool TransportEncryptionHandler::Encrypt(FrameId frame_id,
const base::StringPiece& data,
std::string* encrypted_data) {
if (!is_activated_)
return false;
if (!encryptor_->SetCounter(GetAesNonce(frame_id, iv_mask_))) {
NOTREACHED() << "Failed to set counter";
return false;
}
if (!encryptor_->Encrypt(data, encrypted_data)) {
NOTREACHED() << "Encrypt error";
return false;
}
return true;
}
bool TransportEncryptionHandler::Decrypt(FrameId frame_id,
const base::StringPiece& ciphertext,
std::string* plaintext) {
if (!is_activated_) {
return false;
}
if (!encryptor_->SetCounter(GetAesNonce(frame_id, iv_mask_))) {
NOTREACHED() << "Failed to set counter";
return false;
}
if (!encryptor_->Decrypt(ciphertext, plaintext)) {
VLOG(1) << "Decryption error";
return false;
}
return true;
}
} // namespace cast
} // namespace media