| // 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 "base/logging.h" |
| #include "crypto/encryptor.h" |
| #include "crypto/symmetric_key.h" |
| #include "media/cast/net/cast_transport_defines.h" |
| #include "starboard/types.h" |
| |
| namespace cobalt { |
| 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() {} |
| |
| 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_.reset(new 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 |
| } // namespace cobalt |