media/cdm/aes_decryptor.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "media/cdm/aes_decryptor.h"
   6
   7 #include <list>
   8 #include <vector>
   9
  10 #include "base/logging.h"
  11 #include "base/stl_util.h"
  12 #include "base/strings/string_number_conversions.h"
  13 #include "crypto/encryptor.h"
  14 #include "crypto/symmetric_key.h"
  15 #include "media/base/audio_decoder_config.h"
  16 #include "media/base/cdm_key_information.h"
  17 #include "media/base/cdm_promise.h"
  18 #include "media/base/decoder_buffer.h"
  19 #include "media/base/decrypt_config.h"
  20 #include "media/base/video_decoder_config.h"
  21 #include "media/base/video_frame.h"
  22 #include "media/cdm/cenc_utils.h"
  23 #include "media/cdm/json_web_key.h"
  24
  25 namespace media {
  26
  27 // Keeps track of the session IDs and DecryptionKeys. The keys are ordered by
  28 // insertion time (last insertion is first). It takes ownership of the
  29 // DecryptionKeys.
  30 class AesDecryptor::SessionIdDecryptionKeyMap {
  31   // Use a std::list to actually hold the data. Insertion is always done
  32   // at the front, so the "latest" decryption key is always the first one
  33   // in the list.
  34   typedef std::list<std::pair<std::string, DecryptionKey*> > KeyList;
  35
  36  public:
  37   SessionIdDecryptionKeyMap() {}
  38   ~SessionIdDecryptionKeyMap() { STLDeleteValues(&key_list_); }
  39
  40   // Replaces value if |session_id| is already present, or adds it if not.
  41   // This |decryption_key| becomes the latest until another insertion or
  42   // |session_id| is erased.
  43   void Insert(const std::string& session_id,
  44               scoped_ptr<DecryptionKey> decryption_key);
  45
  46   // Deletes the entry for |session_id| if present.
  47   void Erase(const std::string& session_id);
  48
  49   // Returns whether the list is empty
  50   bool Empty() const { return key_list_.empty(); }
  51
  52   // Returns the last inserted DecryptionKey.
  53   DecryptionKey* LatestDecryptionKey() {
  54     DCHECK(!key_list_.empty());
  55     return key_list_.begin()->second;
  56   }
  57
  58   bool Contains(const std::string& session_id) {
  59     return Find(session_id) != key_list_.end();
  60   }
  61
  62  private:
  63   // Searches the list for an element with |session_id|.
  64   KeyList::iterator Find(const std::string& session_id);
  65
  66   // Deletes the entry pointed to by |position|.
  67   void Erase(KeyList::iterator position);
  68
  69   KeyList key_list_;
  70
  71   DISALLOW_COPY_AND_ASSIGN(SessionIdDecryptionKeyMap);
  72 };
  73
  74 void AesDecryptor::SessionIdDecryptionKeyMap::Insert(
  75     const std::string& session_id,
  76     scoped_ptr<DecryptionKey> decryption_key) {
  77   KeyList::iterator it = Find(session_id);
  78   if (it != key_list_.end())
  79     Erase(it);
  80   DecryptionKey* raw_ptr = decryption_key.release();
  81   key_list_.push_front(std::make_pair(session_id, raw_ptr));
  82 }
  83
  84 void AesDecryptor::SessionIdDecryptionKeyMap::Erase(
  85     const std::string& session_id) {
  86   KeyList::iterator it = Find(session_id);
  87   if (it == key_list_.end())
  88     return;
  89   Erase(it);
  90 }
  91
  92 AesDecryptor::SessionIdDecryptionKeyMap::KeyList::iterator
  93 AesDecryptor::SessionIdDecryptionKeyMap::Find(const std::string& session_id) {
  94   for (KeyList::iterator it = key_list_.begin(); it != key_list_.end(); ++it) {
  95     if (it->first == session_id)
  96       return it;
  97   }
  98   return key_list_.end();
  99 }
 100
 101 void AesDecryptor::SessionIdDecryptionKeyMap::Erase(
 102     KeyList::iterator position) {
 103   DCHECK(position->second);
 104   delete position->second;
 105   key_list_.erase(position);
 106 }
 107
 108 uint32 AesDecryptor::next_session_id_ = 1;
 109
 110 enum ClearBytesBufferSel {
 111   kSrcContainsClearBytes,
 112   kDstContainsClearBytes
 113 };
 114
 115 static void CopySubsamples(const std::vector<SubsampleEntry>& subsamples,
 116                            const ClearBytesBufferSel sel,
 117                            const uint8* src,
 118                            uint8* dst) {
 119   for (size_t i = 0; i < subsamples.size(); i++) {
 120     const SubsampleEntry& subsample = subsamples[i];
 121     if (sel == kSrcContainsClearBytes) {
 122       src += subsample.clear_bytes;
 123     } else {
 124       dst += subsample.clear_bytes;
 125     }
 126     memcpy(dst, src, subsample.cypher_bytes);
 127     src += subsample.cypher_bytes;
 128     dst += subsample.cypher_bytes;
 129   }
 130 }
 131
 132 // Decrypts |input| using |key|.  Returns a DecoderBuffer with the decrypted
 133 // data if decryption succeeded or NULL if decryption failed.
 134 static scoped_refptr<DecoderBuffer> DecryptData(const DecoderBuffer& input,
 135                                                 crypto::SymmetricKey* key) {
 136   CHECK(input.data_size());
 137   CHECK(input.decrypt_config());
 138   CHECK(key);
 139
 140   crypto::Encryptor encryptor;
 141   if (!encryptor.Init(key, crypto::Encryptor::CTR, "")) {
 142     DVLOG(1) << "Could not initialize decryptor.";
 143     return NULL;
 144   }
 145
 146   DCHECK_EQ(input.decrypt_config()->iv().size(),
 147             static_cast<size_t>(DecryptConfig::kDecryptionKeySize));
 148   if (!encryptor.SetCounter(input.decrypt_config()->iv())) {
 149     DVLOG(1) << "Could not set counter block.";
 150     return NULL;
 151   }
 152
 153   const char* sample = reinterpret_cast<const char*>(input.data());
 154   size_t sample_size = static_cast<size_t>(input.data_size());
 155
 156   DCHECK_GT(sample_size, 0U) << "No sample data to be decrypted.";
 157   if (sample_size == 0)
 158     return NULL;
 159
 160   if (input.decrypt_config()->subsamples().empty()) {
 161     std::string decrypted_text;
 162     base::StringPiece encrypted_text(sample, sample_size);
 163     if (!encryptor.Decrypt(encrypted_text, &decrypted_text)) {
 164       DVLOG(1) << "Could not decrypt data.";
 165       return NULL;
 166     }
 167
 168     // TODO(xhwang): Find a way to avoid this data copy.
 169     return DecoderBuffer::CopyFrom(
 170         reinterpret_cast<const uint8*>(decrypted_text.data()),
 171         decrypted_text.size());
 172   }
 173
 174   const std::vector<SubsampleEntry>& subsamples =
 175       input.decrypt_config()->subsamples();
 176
 177   size_t total_clear_size = 0;
 178   size_t total_encrypted_size = 0;
 179   for (size_t i = 0; i < subsamples.size(); i++) {
 180     total_clear_size += subsamples[i].clear_bytes;
 181     total_encrypted_size += subsamples[i].cypher_bytes;
 182     // Check for overflow. This check is valid because *_size is unsigned.
 183     DCHECK(total_clear_size >= subsamples[i].clear_bytes);
 184     if (total_encrypted_size < subsamples[i].cypher_bytes)
 185       return NULL;
 186   }
 187   size_t total_size = total_clear_size + total_encrypted_size;
 188   if (total_size < total_clear_size || total_size != sample_size) {
 189     DVLOG(1) << "Subsample sizes do not equal input size";
 190     return NULL;
 191   }
 192
 193   // No need to decrypt if there is no encrypted data.
 194   if (total_encrypted_size <= 0) {
 195     return DecoderBuffer::CopyFrom(reinterpret_cast<const uint8*>(sample),
 196                                    sample_size);
 197   }
 198
 199   // The encrypted portions of all subsamples must form a contiguous block,
 200   // such that an encrypted subsample that ends away from a block boundary is
 201   // immediately followed by the start of the next encrypted subsample. We
 202   // copy all encrypted subsamples to a contiguous buffer, decrypt them, then
 203   // copy the decrypted bytes over the encrypted bytes in the output.
 204   // TODO(strobe): attempt to reduce number of memory copies
 205   scoped_ptr<uint8[]> encrypted_bytes(new uint8[total_encrypted_size]);
 206   CopySubsamples(subsamples, kSrcContainsClearBytes,
 207                  reinterpret_cast<const uint8*>(sample), encrypted_bytes.get());
 208
 209   base::StringPiece encrypted_text(
 210       reinterpret_cast<const char*>(encrypted_bytes.get()),
 211       total_encrypted_size);
 212   std::string decrypted_text;
 213   if (!encryptor.Decrypt(encrypted_text, &decrypted_text)) {
 214     DVLOG(1) << "Could not decrypt data.";
 215     return NULL;
 216   }
 217   DCHECK_EQ(decrypted_text.size(), encrypted_text.size());
 218
 219   scoped_refptr<DecoderBuffer> output = DecoderBuffer::CopyFrom(
 220       reinterpret_cast<const uint8*>(sample), sample_size);
 221   CopySubsamples(subsamples, kDstContainsClearBytes,
 222                  reinterpret_cast<const uint8*>(decrypted_text.data()),
 223                  output->writable_data());
 224   return output;
 225 }
 226
 227 AesDecryptor::AesDecryptor(const SessionMessageCB& session_message_cb,
 228                            const SessionClosedCB& session_closed_cb,
 229                            const SessionKeysChangeCB& session_keys_change_cb)
 230     : session_message_cb_(session_message_cb),
 231       session_closed_cb_(session_closed_cb),
 232       session_keys_change_cb_(session_keys_change_cb) {
 233   DCHECK(!session_message_cb_.is_null());
 234   DCHECK(!session_closed_cb_.is_null());
 235   DCHECK(!session_keys_change_cb_.is_null());
 236 }
 237
 238 AesDecryptor::~AesDecryptor() {
 239   key_map_.clear();
 240 }
 241
 242 void AesDecryptor::SetServerCertificate(const uint8* certificate_data,
 243                                         int certificate_data_length,
 244                                         scoped_ptr<SimpleCdmPromise> promise) {
 245   promise->reject(
 246       NOT_SUPPORTED_ERROR, 0, "SetServerCertificate() is not supported.");
 247 }
 248
 249 void AesDecryptor::CreateSessionAndGenerateRequest(
 250     SessionType session_type,
 251     EmeInitDataType init_data_type,
 252     const uint8* init_data,
 253     int init_data_length,
 254     scoped_ptr<NewSessionCdmPromise> promise) {
 255   std::string session_id(base::UintToString(next_session_id_++));
 256   valid_sessions_.insert(session_id);
 257
 258   // For now, the AesDecryptor does not care about |session_type|.
 259   // TODO(jrummell): Validate |session_type|.
 260
 261   std::vector<uint8> message;
 262   // TODO(jrummell): Since unprefixed will never send NULL, remove this check
 263   // when prefixed EME is removed (http://crbug.com/249976).
 264   if (init_data && init_data_length) {
 265     std::vector<std::vector<uint8>> keys;
 266     switch (init_data_type) {
 267       case EmeInitDataType::WEBM:
 268         // |init_data| is simply the key needed.
 269         keys.push_back(
 270             std::vector<uint8>(init_data, init_data + init_data_length));
 271         break;
 272       case EmeInitDataType::CENC:
 273         // |init_data| is a set of 0 or more concatenated 'pssh' boxes.
 274         if (!GetKeyIdsForCommonSystemId(init_data, init_data_length, &keys)) {
 275           promise->reject(NOT_SUPPORTED_ERROR, 0,
 276                           "No supported PSSH box found.");
 277           return;
 278         }
 279         break;
 280       case EmeInitDataType::KEYIDS: {
 281         std::string init_data_string(init_data, init_data + init_data_length);
 282         std::string error_message;
 283         if (!ExtractKeyIdsFromKeyIdsInitData(init_data_string, &keys,
 284                                              &error_message)) {
 285           promise->reject(NOT_SUPPORTED_ERROR, 0, error_message);
 286           return;
 287         }
 288         break;
 289       }
 290       default:
 291         NOTREACHED();
 292         promise->reject(NOT_SUPPORTED_ERROR, 0,
 293                         "init_data_type not supported.");
 294         return;
 295     }
 296     CreateLicenseRequest(keys, session_type, &message);
 297   }
 298
 299   promise->resolve(session_id);
 300
 301   // No URL needed for license requests.
 302   session_message_cb_.Run(session_id, LICENSE_REQUEST, message,
 303                           GURL::EmptyGURL());
 304 }
 305
 306 void AesDecryptor::LoadSession(SessionType session_type,
 307                                const std::string& session_id,
 308                                scoped_ptr<NewSessionCdmPromise> promise) {
 309   // TODO(xhwang): Change this to NOTREACHED() when blink checks for key systems
 310   // that do not support loadSession. See http://crbug.com/342481
 311   promise->reject(NOT_SUPPORTED_ERROR, 0, "LoadSession() is not supported.");
 312 }
 313
 314 void AesDecryptor::UpdateSession(const std::string& session_id,
 315                                  const uint8* response,
 316                                  int response_length,
 317                                  scoped_ptr<SimpleCdmPromise> promise) {
 318   CHECK(response);
 319   CHECK_GT(response_length, 0);
 320
 321   // TODO(jrummell): Convert back to a DCHECK once prefixed EME is removed.
 322   if (valid_sessions_.find(session_id) == valid_sessions_.end()) {
 323     promise->reject(INVALID_ACCESS_ERROR, 0, "Session does not exist.");
 324     return;
 325   }
 326
 327   std::string key_string(reinterpret_cast<const char*>(response),
 328                          response_length);
 329
 330   KeyIdAndKeyPairs keys;
 331   SessionType session_type = MediaKeys::TEMPORARY_SESSION;
 332   if (!ExtractKeysFromJWKSet(key_string, &keys, &session_type)) {
 333     promise->reject(
 334         INVALID_ACCESS_ERROR, 0, "Response is not a valid JSON Web Key Set.");
 335     return;
 336   }
 337
 338   // Make sure that at least one key was extracted.
 339   if (keys.empty()) {
 340     promise->reject(
 341         INVALID_ACCESS_ERROR, 0, "Response does not contain any keys.");
 342     return;
 343   }
 344
 345   bool key_added = false;
 346   for (KeyIdAndKeyPairs::iterator it = keys.begin(); it != keys.end(); ++it) {
 347     if (it->second.length() !=
 348         static_cast<size_t>(DecryptConfig::kDecryptionKeySize)) {
 349       DVLOG(1) << "Invalid key length: " << it->second.length();
 350       promise->reject(INVALID_ACCESS_ERROR, 0, "Invalid key length.");
 351       return;
 352     }
 353
 354     // If this key_id doesn't currently exist in this session,
 355     // a new key is added.
 356     if (!HasKey(session_id, it->first))
 357       key_added = true;
 358
 359     if (!AddDecryptionKey(session_id, it->first, it->second)) {
 360       promise->reject(INVALID_ACCESS_ERROR, 0, "Unable to add key.");
 361       return;
 362     }
 363   }
 364
 365   {
 366     base::AutoLock auto_lock(new_key_cb_lock_);
 367
 368     if (!new_audio_key_cb_.is_null())
 369       new_audio_key_cb_.Run();
 370
 371     if (!new_video_key_cb_.is_null())
 372       new_video_key_cb_.Run();
 373   }
 374
 375   promise->resolve();
 376
 377   // Create the list of all available keys for this session.
 378   CdmKeysInfo keys_info;
 379   {
 380     base::AutoLock auto_lock(key_map_lock_);
 381     for (const auto& item : key_map_) {
 382       if (item.second->Contains(session_id)) {
 383         scoped_ptr<CdmKeyInformation> key_info(new CdmKeyInformation);
 384         key_info->key_id.assign(item.first.begin(), item.first.end());
 385         key_info->status = CdmKeyInformation::USABLE;
 386         key_info->system_code = 0;
 387         keys_info.push_back(key_info.release());
 388       }
 389     }
 390   }
 391
 392   session_keys_change_cb_.Run(session_id, key_added, keys_info.Pass());
 393 }
 394
 395 void AesDecryptor::CloseSession(const std::string& session_id,
 396                                 scoped_ptr<SimpleCdmPromise> promise) {
 397   // Validate that this is a reference to an active session and then forget it.
 398   std::set<std::string>::iterator it = valid_sessions_.find(session_id);
 399   DCHECK(it != valid_sessions_.end());
 400
 401   valid_sessions_.erase(it);
 402
 403   // Close the session.
 404   DeleteKeysForSession(session_id);
 405   promise->resolve();
 406   session_closed_cb_.Run(session_id);
 407 }
 408
 409 void AesDecryptor::RemoveSession(const std::string& session_id,
 410                                  scoped_ptr<SimpleCdmPromise> promise) {
 411   // AesDecryptor doesn't keep any persistent data, so this should be
 412   // NOT_REACHED().
 413   // TODO(jrummell): Make sure persistent session types are rejected.
 414   // http://crbug.com/384152.
 415   //
 416   // However, v0.1b calls to CancelKeyRequest() will call this, so close the
 417   // session, if it exists.
 418   // TODO(jrummell): Remove the close() call when prefixed EME is removed.
 419   // http://crbug.com/249976.
 420   if (valid_sessions_.find(session_id) != valid_sessions_.end()) {
 421     CloseSession(session_id, promise.Pass());
 422     return;
 423   }
 424
 425   promise->reject(INVALID_ACCESS_ERROR, 0, "Session does not exist.");
 426 }
 427
 428 CdmContext* AesDecryptor::GetCdmContext() {
 429   return this;
 430 }
 431
 432 Decryptor* AesDecryptor::GetDecryptor() {
 433   return this;
 434 }
 435
 436 int AesDecryptor::GetCdmId() const {
 437   return kInvalidCdmId;
 438 }
 439
 440 void AesDecryptor::RegisterNewKeyCB(StreamType stream_type,
 441                                     const NewKeyCB& new_key_cb) {
 442   base::AutoLock auto_lock(new_key_cb_lock_);
 443
 444   switch (stream_type) {
 445     case kAudio:
 446       new_audio_key_cb_ = new_key_cb;
 447       break;
 448     case kVideo:
 449       new_video_key_cb_ = new_key_cb;
 450       break;
 451     default:
 452       NOTREACHED();
 453   }
 454 }
 455
 456 void AesDecryptor::Decrypt(StreamType stream_type,
 457                            const scoped_refptr<DecoderBuffer>& encrypted,
 458                            const DecryptCB& decrypt_cb) {
 459   CHECK(encrypted->decrypt_config());
 460
 461   scoped_refptr<DecoderBuffer> decrypted;
 462   // An empty iv string signals that the frame is unencrypted.
 463   if (encrypted->decrypt_config()->iv().empty()) {
 464     decrypted = DecoderBuffer::CopyFrom(encrypted->data(),
 465                                         encrypted->data_size());
 466   } else {
 467     const std::string& key_id = encrypted->decrypt_config()->key_id();
 468     DecryptionKey* key = GetKey(key_id);
 469     if (!key) {
 470       DVLOG(1) << "Could not find a matching key for the given key ID.";
 471       decrypt_cb.Run(kNoKey, NULL);
 472       return;
 473     }
 474
 475     crypto::SymmetricKey* decryption_key = key->decryption_key();
 476     decrypted = DecryptData(*encrypted.get(), decryption_key);
 477     if (!decrypted.get()) {
 478       DVLOG(1) << "Decryption failed.";
 479       decrypt_cb.Run(kError, NULL);
 480       return;
 481     }
 482   }
 483
 484   decrypted->set_timestamp(encrypted->timestamp());
 485   decrypted->set_duration(encrypted->duration());
 486   decrypt_cb.Run(kSuccess, decrypted);
 487 }
 488
 489 void AesDecryptor::CancelDecrypt(StreamType stream_type) {
 490   // Decrypt() calls the DecryptCB synchronously so there's nothing to cancel.
 491 }
 492
 493 void AesDecryptor::InitializeAudioDecoder(const AudioDecoderConfig& config,
 494                                           const DecoderInitCB& init_cb) {
 495   // AesDecryptor does not support audio decoding.
 496   init_cb.Run(false);
 497 }
 498
 499 void AesDecryptor::InitializeVideoDecoder(const VideoDecoderConfig& config,
 500                                           const DecoderInitCB& init_cb) {
 501   // AesDecryptor does not support video decoding.
 502   init_cb.Run(false);
 503 }
 504
 505 void AesDecryptor::DecryptAndDecodeAudio(
 506     const scoped_refptr<DecoderBuffer>& encrypted,
 507     const AudioDecodeCB& audio_decode_cb) {
 508   NOTREACHED() << "AesDecryptor does not support audio decoding";
 509 }
 510
 511 void AesDecryptor::DecryptAndDecodeVideo(
 512     const scoped_refptr<DecoderBuffer>& encrypted,
 513     const VideoDecodeCB& video_decode_cb) {
 514   NOTREACHED() << "AesDecryptor does not support video decoding";
 515 }
 516
 517 void AesDecryptor::ResetDecoder(StreamType stream_type) {
 518   NOTREACHED() << "AesDecryptor does not support audio/video decoding";
 519 }
 520
 521 void AesDecryptor::DeinitializeDecoder(StreamType stream_type) {
 522   NOTREACHED() << "AesDecryptor does not support audio/video decoding";
 523 }
 524
 525 bool AesDecryptor::AddDecryptionKey(const std::string& session_id,
 526                                     const std::string& key_id,
 527                                     const std::string& key_string) {
 528   scoped_ptr<DecryptionKey> decryption_key(new DecryptionKey(key_string));
 529   if (!decryption_key->Init()) {
 530     DVLOG(1) << "Could not initialize decryption key.";
 531     return false;
 532   }
 533
 534   base::AutoLock auto_lock(key_map_lock_);
 535   KeyIdToSessionKeysMap::iterator key_id_entry = key_map_.find(key_id);
 536   if (key_id_entry != key_map_.end()) {
 537     key_id_entry->second->Insert(session_id, decryption_key.Pass());
 538     return true;
 539   }
 540
 541   // |key_id| not found, so need to create new entry.
 542   scoped_ptr<SessionIdDecryptionKeyMap> inner_map(
 543       new SessionIdDecryptionKeyMap());
 544   inner_map->Insert(session_id, decryption_key.Pass());
 545   key_map_.add(key_id, inner_map.Pass());
 546   return true;
 547 }
 548
 549 AesDecryptor::DecryptionKey* AesDecryptor::GetKey(
 550     const std::string& key_id) const {
 551   base::AutoLock auto_lock(key_map_lock_);
 552   KeyIdToSessionKeysMap::const_iterator key_id_found = key_map_.find(key_id);
 553   if (key_id_found == key_map_.end())
 554     return NULL;
 555
 556   // Return the key from the "latest" session_id entry.
 557   return key_id_found->second->LatestDecryptionKey();
 558 }
 559
 560 bool AesDecryptor::HasKey(const std::string& session_id,
 561                           const std::string& key_id) {
 562   base::AutoLock auto_lock(key_map_lock_);
 563   KeyIdToSessionKeysMap::const_iterator key_id_found = key_map_.find(key_id);
 564   if (key_id_found == key_map_.end())
 565     return false;
 566
 567   return key_id_found->second->Contains(session_id);
 568 }
 569
 570 void AesDecryptor::DeleteKeysForSession(const std::string& session_id) {
 571   base::AutoLock auto_lock(key_map_lock_);
 572
 573   // Remove all keys associated with |session_id|. Since the data is
 574   // optimized for access in GetKey(), we need to look at each entry in
 575   // |key_map_|.
 576   KeyIdToSessionKeysMap::iterator it = key_map_.begin();
 577   while (it != key_map_.end()) {
 578     it->second->Erase(session_id);
 579     if (it->second->Empty()) {
 580       // Need to get rid of the entry for this key_id. This will mess up the
 581       // iterator, so we need to increment it first.
 582       KeyIdToSessionKeysMap::iterator current = it;
 583       ++it;
 584       key_map_.erase(current);
 585     } else {
 586       ++it;
 587     }
 588   }
 589 }
 590
 591 AesDecryptor::DecryptionKey::DecryptionKey(const std::string& secret)
 592     : secret_(secret) {
 593 }
 594
 595 AesDecryptor::DecryptionKey::~DecryptionKey() {}
 596
 597 bool AesDecryptor::DecryptionKey::Init() {
 598   CHECK(!secret_.empty());
 599   decryption_key_.reset(crypto::SymmetricKey::Import(
 600       crypto::SymmetricKey::AES, secret_));
 601   if (!decryption_key_)
 602     return false;
 603   return true;
 604 }
 605
 606 }  // namespace media