| // Copyright 2013 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/cdm/aes_decryptor.h" |
| |
| #include <vector> |
| |
| #include "base/logging.h" |
| #include "base/stl_util.h" |
| #include "base/strings/string_number_conversions.h" |
| #include "crypto/encryptor.h" |
| #include "crypto/symmetric_key.h" |
| #include "media/base/audio_decoder_config.h" |
| #include "media/base/decoder_buffer.h" |
| #include "media/base/decrypt_config.h" |
| #include "media/base/video_decoder_config.h" |
| #include "media/base/video_frame.h" |
| |
| namespace media { |
| |
| uint32 AesDecryptor::next_session_id_ = 1; |
| |
| enum ClearBytesBufferSel { |
| kSrcContainsClearBytes, |
| kDstContainsClearBytes |
| }; |
| |
| static void CopySubsamples(const std::vector<SubsampleEntry>& subsamples, |
| const ClearBytesBufferSel sel, |
| const uint8* src, |
| uint8* dst) { |
| for (size_t i = 0; i < subsamples.size(); i++) { |
| const SubsampleEntry& subsample = subsamples[i]; |
| if (sel == kSrcContainsClearBytes) { |
| src += subsample.clear_bytes; |
| } else { |
| dst += subsample.clear_bytes; |
| } |
| memcpy(dst, src, subsample.cypher_bytes); |
| src += subsample.cypher_bytes; |
| dst += subsample.cypher_bytes; |
| } |
| } |
| |
| // Decrypts |input| using |key|. Returns a DecoderBuffer with the decrypted |
| // data if decryption succeeded or NULL if decryption failed. |
| static scoped_refptr<DecoderBuffer> DecryptData(const DecoderBuffer& input, |
| crypto::SymmetricKey* key) { |
| CHECK(input.data_size()); |
| CHECK(input.decrypt_config()); |
| CHECK(key); |
| |
| crypto::Encryptor encryptor; |
| if (!encryptor.Init(key, crypto::Encryptor::CTR, "")) { |
| DVLOG(1) << "Could not initialize decryptor."; |
| return NULL; |
| } |
| |
| DCHECK_EQ(input.decrypt_config()->iv().size(), |
| static_cast<size_t>(DecryptConfig::kDecryptionKeySize)); |
| if (!encryptor.SetCounter(input.decrypt_config()->iv())) { |
| DVLOG(1) << "Could not set counter block."; |
| return NULL; |
| } |
| |
| const int data_offset = input.decrypt_config()->data_offset(); |
| const char* sample = |
| reinterpret_cast<const char*>(input.data() + data_offset); |
| int sample_size = input.data_size() - data_offset; |
| |
| DCHECK_GT(sample_size, 0) << "No sample data to be decrypted."; |
| if (sample_size <= 0) |
| return NULL; |
| |
| if (input.decrypt_config()->subsamples().empty()) { |
| std::string decrypted_text; |
| base::StringPiece encrypted_text(sample, sample_size); |
| if (!encryptor.Decrypt(encrypted_text, &decrypted_text)) { |
| DVLOG(1) << "Could not decrypt data."; |
| return NULL; |
| } |
| |
| // TODO(xhwang): Find a way to avoid this data copy. |
| return DecoderBuffer::CopyFrom( |
| reinterpret_cast<const uint8*>(decrypted_text.data()), |
| decrypted_text.size()); |
| } |
| |
| const std::vector<SubsampleEntry>& subsamples = |
| input.decrypt_config()->subsamples(); |
| |
| int total_clear_size = 0; |
| int total_encrypted_size = 0; |
| for (size_t i = 0; i < subsamples.size(); i++) { |
| total_clear_size += subsamples[i].clear_bytes; |
| total_encrypted_size += subsamples[i].cypher_bytes; |
| } |
| if (total_clear_size + total_encrypted_size != sample_size) { |
| DVLOG(1) << "Subsample sizes do not equal input size"; |
| return NULL; |
| } |
| |
| // No need to decrypt if there is no encrypted data. |
| if (total_encrypted_size <= 0) { |
| return DecoderBuffer::CopyFrom(reinterpret_cast<const uint8*>(sample), |
| sample_size); |
| } |
| |
| // The encrypted portions of all subsamples must form a contiguous block, |
| // such that an encrypted subsample that ends away from a block boundary is |
| // immediately followed by the start of the next encrypted subsample. We |
| // copy all encrypted subsamples to a contiguous buffer, decrypt them, then |
| // copy the decrypted bytes over the encrypted bytes in the output. |
| // TODO(strobe): attempt to reduce number of memory copies |
| scoped_ptr<uint8[]> encrypted_bytes(new uint8[total_encrypted_size]); |
| CopySubsamples(subsamples, kSrcContainsClearBytes, |
| reinterpret_cast<const uint8*>(sample), encrypted_bytes.get()); |
| |
| base::StringPiece encrypted_text( |
| reinterpret_cast<const char*>(encrypted_bytes.get()), |
| total_encrypted_size); |
| std::string decrypted_text; |
| if (!encryptor.Decrypt(encrypted_text, &decrypted_text)) { |
| DVLOG(1) << "Could not decrypt data."; |
| return NULL; |
| } |
| DCHECK_EQ(decrypted_text.size(), encrypted_text.size()); |
| |
| scoped_refptr<DecoderBuffer> output = DecoderBuffer::CopyFrom( |
| reinterpret_cast<const uint8*>(sample), sample_size); |
| CopySubsamples(subsamples, kDstContainsClearBytes, |
| reinterpret_cast<const uint8*>(decrypted_text.data()), |
| output->writable_data()); |
| return output; |
| } |
| |
| AesDecryptor::AesDecryptor(const KeyAddedCB& key_added_cb, |
| const KeyErrorCB& key_error_cb, |
| const KeyMessageCB& key_message_cb) |
| : key_added_cb_(key_added_cb), |
| key_error_cb_(key_error_cb), |
| key_message_cb_(key_message_cb) { |
| } |
| |
| AesDecryptor::~AesDecryptor() { |
| STLDeleteValues(&key_map_); |
| } |
| |
| bool AesDecryptor::GenerateKeyRequest(const std::string& type, |
| const uint8* init_data, |
| int init_data_length) { |
| std::string session_id_string(base::UintToString(next_session_id_++)); |
| |
| // For now, the AesDecryptor does not care about |type|; |
| // just fire the event with the |init_data| as the request. |
| std::vector<uint8> message; |
| if (init_data && init_data_length) |
| message.assign(init_data, init_data + init_data_length); |
| |
| key_message_cb_.Run(session_id_string, message, std::string()); |
| return true; |
| } |
| |
| void AesDecryptor::AddKey(const uint8* key, |
| int key_length, |
| const uint8* init_data, |
| int init_data_length, |
| const std::string& session_id) { |
| CHECK(key); |
| CHECK_GT(key_length, 0); |
| |
| // TODO(xhwang): Add |session_id| check after we figure out how: |
| // https://www.w3.org/Bugs/Public/show_bug.cgi?id=16550 |
| if (key_length != DecryptConfig::kDecryptionKeySize) { |
| DVLOG(1) << "Invalid key length: " << key_length; |
| key_error_cb_.Run(session_id, MediaKeys::kUnknownError, 0); |
| return; |
| } |
| |
| // TODO(xhwang): Fix the decryptor to accept no |init_data|. See |
| // http://crbug.com/123265. Until then, ensure a non-empty value is passed. |
| static const uint8 kDummyInitData[1] = { 0 }; |
| if (!init_data) { |
| init_data = kDummyInitData; |
| init_data_length = arraysize(kDummyInitData); |
| } |
| |
| // TODO(xhwang): For now, use |init_data| for key ID. Make this more spec |
| // compliant later (http://crbug.com/123262, http://crbug.com/123265). |
| std::string key_id_string(reinterpret_cast<const char*>(init_data), |
| init_data_length); |
| std::string key_string(reinterpret_cast<const char*>(key) , key_length); |
| scoped_ptr<DecryptionKey> decryption_key(new DecryptionKey(key_string)); |
| if (!decryption_key) { |
| DVLOG(1) << "Could not create key."; |
| key_error_cb_.Run(session_id, MediaKeys::kUnknownError, 0); |
| return; |
| } |
| |
| if (!decryption_key->Init()) { |
| DVLOG(1) << "Could not initialize decryption key."; |
| key_error_cb_.Run(session_id, MediaKeys::kUnknownError, 0); |
| return; |
| } |
| |
| SetKey(key_id_string, decryption_key.Pass()); |
| |
| if (!new_audio_key_cb_.is_null()) |
| new_audio_key_cb_.Run(); |
| |
| if (!new_video_key_cb_.is_null()) |
| new_video_key_cb_.Run(); |
| |
| key_added_cb_.Run(session_id); |
| } |
| |
| void AesDecryptor::CancelKeyRequest(const std::string& session_id) { |
| } |
| |
| Decryptor* AesDecryptor::GetDecryptor() { |
| return this; |
| } |
| |
| void AesDecryptor::RegisterNewKeyCB(StreamType stream_type, |
| const NewKeyCB& new_key_cb) { |
| switch (stream_type) { |
| case kAudio: |
| new_audio_key_cb_ = new_key_cb; |
| break; |
| case kVideo: |
| new_video_key_cb_ = new_key_cb; |
| break; |
| default: |
| NOTREACHED(); |
| } |
| } |
| |
| void AesDecryptor::Decrypt(StreamType stream_type, |
| const scoped_refptr<DecoderBuffer>& encrypted, |
| const DecryptCB& decrypt_cb) { |
| CHECK(encrypted->decrypt_config()); |
| |
| scoped_refptr<DecoderBuffer> decrypted; |
| // An empty iv string signals that the frame is unencrypted. |
| if (encrypted->decrypt_config()->iv().empty()) { |
| int data_offset = encrypted->decrypt_config()->data_offset(); |
| decrypted = DecoderBuffer::CopyFrom(encrypted->data() + data_offset, |
| encrypted->data_size() - data_offset); |
| } else { |
| const std::string& key_id = encrypted->decrypt_config()->key_id(); |
| DecryptionKey* key = GetKey(key_id); |
| if (!key) { |
| DVLOG(1) << "Could not find a matching key for the given key ID."; |
| decrypt_cb.Run(kNoKey, NULL); |
| return; |
| } |
| |
| crypto::SymmetricKey* decryption_key = key->decryption_key(); |
| decrypted = DecryptData(*encrypted.get(), decryption_key); |
| if (!decrypted.get()) { |
| DVLOG(1) << "Decryption failed."; |
| decrypt_cb.Run(kError, NULL); |
| return; |
| } |
| } |
| |
| decrypted->set_timestamp(encrypted->timestamp()); |
| decrypted->set_duration(encrypted->duration()); |
| decrypt_cb.Run(kSuccess, decrypted); |
| } |
| |
| void AesDecryptor::CancelDecrypt(StreamType stream_type) { |
| // Decrypt() calls the DecryptCB synchronously so there's nothing to cancel. |
| } |
| |
| void AesDecryptor::InitializeAudioDecoder(const AudioDecoderConfig& config, |
| const DecoderInitCB& init_cb) { |
| // AesDecryptor does not support audio decoding. |
| init_cb.Run(false); |
| } |
| |
| void AesDecryptor::InitializeVideoDecoder(const VideoDecoderConfig& config, |
| const DecoderInitCB& init_cb) { |
| // AesDecryptor does not support video decoding. |
| init_cb.Run(false); |
| } |
| |
| void AesDecryptor::DecryptAndDecodeAudio( |
| const scoped_refptr<DecoderBuffer>& encrypted, |
| const AudioDecodeCB& audio_decode_cb) { |
| NOTREACHED() << "AesDecryptor does not support audio decoding"; |
| } |
| |
| void AesDecryptor::DecryptAndDecodeVideo( |
| const scoped_refptr<DecoderBuffer>& encrypted, |
| const VideoDecodeCB& video_decode_cb) { |
| NOTREACHED() << "AesDecryptor does not support video decoding"; |
| } |
| |
| void AesDecryptor::ResetDecoder(StreamType stream_type) { |
| NOTREACHED() << "AesDecryptor does not support audio/video decoding"; |
| } |
| |
| void AesDecryptor::DeinitializeDecoder(StreamType stream_type) { |
| NOTREACHED() << "AesDecryptor does not support audio/video decoding"; |
| } |
| |
| void AesDecryptor::SetKey(const std::string& key_id, |
| scoped_ptr<DecryptionKey> decryption_key) { |
| base::AutoLock auto_lock(key_map_lock_); |
| KeyMap::iterator found = key_map_.find(key_id); |
| if (found != key_map_.end()) { |
| delete found->second; |
| key_map_.erase(found); |
| } |
| key_map_[key_id] = decryption_key.release(); |
| } |
| |
| AesDecryptor::DecryptionKey* AesDecryptor::GetKey( |
| const std::string& key_id) const { |
| base::AutoLock auto_lock(key_map_lock_); |
| KeyMap::const_iterator found = key_map_.find(key_id); |
| if (found == key_map_.end()) |
| return NULL; |
| |
| return found->second; |
| } |
| |
| AesDecryptor::DecryptionKey::DecryptionKey(const std::string& secret) |
| : secret_(secret) { |
| } |
| |
| AesDecryptor::DecryptionKey::~DecryptionKey() {} |
| |
| bool AesDecryptor::DecryptionKey::Init() { |
| CHECK(!secret_.empty()); |
| decryption_key_.reset(crypto::SymmetricKey::Import( |
| crypto::SymmetricKey::AES, secret_)); |
| if (!decryption_key_) |
| return false; |
| return true; |
| } |
| |
| } // namespace media |