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_t 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_t* src,
 118                            uint8_t* 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_t*>(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_t*>(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_t[]> encrypted_bytes(new uint8_t[total_encrypted_size]);
 206   CopySubsamples(subsamples, kSrcContainsClearBytes,
 207                  reinterpret_cast<const uint8_t*>(sample),
 208                  encrypted_bytes.get());
 209
 210   base::StringPiece encrypted_text(
 211       reinterpret_cast<const char*>(encrypted_bytes.get()),
 212       total_encrypted_size);
 213   std::string decrypted_text;
 214   if (!encryptor.Decrypt(encrypted_text, &decrypted_text)) {
 215     DVLOG(1) << "Could not decrypt data.";
 216     return NULL;
 217   }
 218   DCHECK_EQ(decrypted_text.size(), encrypted_text.size());
 219
 220   scoped_refptr<DecoderBuffer> output = DecoderBuffer::CopyFrom(
 221       reinterpret_cast<const uint8_t*>(sample), sample_size);
 222   CopySubsamples(subsamples, kDstContainsClearBytes,
 223                  reinterpret_cast<const uint8_t*>(decrypted_text.data()),
 224                  output->writable_data());
 225   return output;
 226 }
 227
 228 AesDecryptor::AesDecryptor(const GURL& /* security_origin */,
 229                            const SessionMessageCB& session_message_cb,
 230                            const SessionClosedCB& session_closed_cb,
 231                            const SessionKeysChangeCB& session_keys_change_cb)
 232     : session_message_cb_(session_message_cb),
 233       session_closed_cb_(session_closed_cb),
 234       session_keys_change_cb_(session_keys_change_cb) {
 235   // AesDecryptor doesn't keep any persistent data, so no need to do anything
 236   // with |security_origin|.
 237   DCHECK(!session_message_cb_.is_null());
 238   DCHECK(!session_closed_cb_.is_null());
 239   DCHECK(!session_keys_change_cb_.is_null());
 240 }
 241
 242 AesDecryptor::~AesDecryptor() {
 243   key_map_.clear();
 244 }
 245
 246 void AesDecryptor::SetServerCertificate(const std::vector<uint8_t>& certificate,
 247                                         scoped_ptr<SimpleCdmPromise> promise) {
 248   promise->reject(
 249       NOT_SUPPORTED_ERROR, 0, "SetServerCertificate() is not supported.");
 250 }
 251
 252 void AesDecryptor::CreateSessionAndGenerateRequest(
 253     SessionType session_type,
 254     EmeInitDataType init_data_type,
 255     const std::vector<uint8_t>& init_data,
 256     scoped_ptr<NewSessionCdmPromise> promise) {
 257   std::string session_id(base::UintToString(next_session_id_++));
 258   valid_sessions_.insert(session_id);
 259
 260   // For now, the AesDecryptor does not care about |session_type|.
 261   // TODO(jrummell): Validate |session_type|.
 262
 263   std::vector<uint8_t> message;
 264   // TODO(jrummell): Since unprefixed will never send NULL, remove this check
 265   // when prefixed EME is removed (http://crbug.com/249976).
 266   if (!init_data.empty()) {
 267     std::vector<std::vector<uint8_t>> keys;
 268     switch (init_data_type) {
 269       case EmeInitDataType::WEBM:
 270         // |init_data| is simply the key needed.
 271         keys.push_back(init_data);
 272         break;
 273       case EmeInitDataType::CENC:
 274         // |init_data| is a set of 0 or more concatenated 'pssh' boxes.
 275         if (!GetKeyIdsForCommonSystemId(init_data, &keys)) {
 276           promise->reject(NOT_SUPPORTED_ERROR, 0,
 277                           "No supported PSSH box found.");
 278           return;
 279         }
 280         break;
 281       case EmeInitDataType::KEYIDS: {
 282         std::string init_data_string(init_data.begin(), init_data.end());
 283         std::string error_message;
 284         if (!ExtractKeyIdsFromKeyIdsInitData(init_data_string, &keys,
 285                                              &error_message)) {
 286           promise->reject(NOT_SUPPORTED_ERROR, 0, error_message);
 287           return;
 288         }
 289         break;
 290       }
 291       default:
 292         NOTREACHED();
 293         promise->reject(NOT_SUPPORTED_ERROR, 0,
 294                         "init_data_type not supported.");
 295         return;
 296     }
 297     CreateLicenseRequest(keys, session_type, &message);
 298   }
 299
 300   promise->resolve(session_id);
 301
 302   // No URL needed for license requests.
 303   session_message_cb_.Run(session_id, LICENSE_REQUEST, message,
 304                           GURL::EmptyGURL());
 305 }
 306
 307 void AesDecryptor::LoadSession(SessionType session_type,
 308                                const std::string& session_id,
 309                                scoped_ptr<NewSessionCdmPromise> promise) {
 310   // TODO(xhwang): Change this to NOTREACHED() when blink checks for key systems
 311   // that do not support loadSession. See http://crbug.com/342481
 312   promise->reject(NOT_SUPPORTED_ERROR, 0, "LoadSession() is not supported.");
 313 }
 314
 315 void AesDecryptor::UpdateSession(const std::string& session_id,
 316                                  const std::vector<uint8_t>& response,
 317                                  scoped_ptr<SimpleCdmPromise> promise) {
 318   CHECK(!response.empty());
 319
 320   // TODO(jrummell): Convert back to a DCHECK once prefixed EME is removed.
 321   if (valid_sessions_.find(session_id) == valid_sessions_.end()) {
 322     promise->reject(INVALID_ACCESS_ERROR, 0, "Session does not exist.");
 323     return;
 324   }
 325
 326   std::string key_string(response.begin(), response.end());
 327
 328   KeyIdAndKeyPairs keys;
 329   SessionType session_type = MediaKeys::TEMPORARY_SESSION;
 330   if (!ExtractKeysFromJWKSet(key_string, &keys, &session_type)) {
 331     promise->reject(
 332         INVALID_ACCESS_ERROR, 0, "Response is not a valid JSON Web Key Set.");
 333     return;
 334   }
 335
 336   // Make sure that at least one key was extracted.
 337   if (keys.empty()) {
 338     promise->reject(
 339         INVALID_ACCESS_ERROR, 0, "Response does not contain any keys.");
 340     return;
 341   }
 342
 343   bool key_added = false;
 344   for (KeyIdAndKeyPairs::iterator it = keys.begin(); it != keys.end(); ++it) {
 345     if (it->second.length() !=
 346         static_cast<size_t>(DecryptConfig::kDecryptionKeySize)) {
 347       DVLOG(1) << "Invalid key length: " << it->second.length();
 348       promise->reject(INVALID_ACCESS_ERROR, 0, "Invalid key length.");
 349       return;
 350     }
 351
 352     // If this key_id doesn't currently exist in this session,
 353     // a new key is added.
 354     if (!HasKey(session_id, it->first))
 355       key_added = true;
 356
 357     if (!AddDecryptionKey(session_id, it->first, it->second)) {
 358       promise->reject(INVALID_ACCESS_ERROR, 0, "Unable to add key.");
 359       return;
 360     }
 361   }
 362
 363   {
 364     base::AutoLock auto_lock(new_key_cb_lock_);
 365
 366     if (!new_audio_key_cb_.is_null())
 367       new_audio_key_cb_.Run();
 368
 369     if (!new_video_key_cb_.is_null())
 370       new_video_key_cb_.Run();
 371   }
 372
 373   promise->resolve();
 374
 375   // Create the list of all available keys for this session.
 376   CdmKeysInfo keys_info;
 377   {
 378     base::AutoLock auto_lock(key_map_lock_);
 379     for (const auto& item : key_map_) {
 380       if (item.second->Contains(session_id)) {
 381         scoped_ptr<CdmKeyInformation> key_info(new CdmKeyInformation);
 382         key_info->key_id.assign(item.first.begin(), item.first.end());
 383         key_info->status = CdmKeyInformation::USABLE;
 384         key_info->system_code = 0;
 385         keys_info.push_back(key_info.release());
 386       }
 387     }
 388   }
 389
 390   session_keys_change_cb_.Run(session_id, key_added, keys_info.Pass());
 391 }
 392
 393 void AesDecryptor::CloseSession(const std::string& session_id,
 394                                 scoped_ptr<SimpleCdmPromise> promise) {
 395   // Validate that this is a reference to an active session and then forget it.
 396   std::set<std::string>::iterator it = valid_sessions_.find(session_id);
 397   DCHECK(it != valid_sessions_.end());
 398
 399   valid_sessions_.erase(it);
 400
 401   // Close the session.
 402   DeleteKeysForSession(session_id);
 403   promise->resolve();
 404   session_closed_cb_.Run(session_id);
 405 }
 406
 407 void AesDecryptor::RemoveSession(const std::string& session_id,
 408                                  scoped_ptr<SimpleCdmPromise> promise) {
 409   // AesDecryptor doesn't keep any persistent data, so this should be
 410   // NOT_REACHED().
 411   // TODO(jrummell): Make sure persistent session types are rejected.
 412   // http://crbug.com/384152.
 413   //
 414   // However, v0.1b calls to CancelKeyRequest() will call this, so close the
 415   // session, if it exists.
 416   // TODO(jrummell): Remove the close() call when prefixed EME is removed.
 417   // http://crbug.com/249976.
 418   if (valid_sessions_.find(session_id) != valid_sessions_.end()) {
 419     CloseSession(session_id, promise.Pass());
 420     return;
 421   }
 422
 423   promise->reject(INVALID_ACCESS_ERROR, 0, "Session does not exist.");
 424 }
 425
 426 CdmContext* AesDecryptor::GetCdmContext() {
 427   return this;
 428 }
 429
 430 Decryptor* AesDecryptor::GetDecryptor() {
 431   return this;
 432 }
 433
 434 int AesDecryptor::GetCdmId() const {
 435   return kInvalidCdmId;
 436 }
 437
 438 void AesDecryptor::RegisterNewKeyCB(StreamType stream_type,
 439                                     const NewKeyCB& new_key_cb) {
 440   base::AutoLock auto_lock(new_key_cb_lock_);
 441
 442   switch (stream_type) {
 443     case kAudio:
 444       new_audio_key_cb_ = new_key_cb;
 445       break;
 446     case kVideo:
 447       new_video_key_cb_ = new_key_cb;
 448       break;
 449     default:
 450       NOTREACHED();
 451   }
 452 }
 453
 454 void AesDecryptor::Decrypt(StreamType stream_type,
 455                            const scoped_refptr<DecoderBuffer>& encrypted,
 456                            const DecryptCB& decrypt_cb) {
 457   CHECK(encrypted->decrypt_config());
 458
 459   scoped_refptr<DecoderBuffer> decrypted;
 460   // An empty iv string signals that the frame is unencrypted.
 461   if (encrypted->decrypt_config()->iv().empty()) {
 462     decrypted = DecoderBuffer::CopyFrom(encrypted->data(),
 463                                         encrypted->data_size());
 464   } else {
 465     const std::string& key_id = encrypted->decrypt_config()->key_id();
 466     DecryptionKey* key = GetKey(key_id);
 467     if (!key) {
 468       DVLOG(1) << "Could not find a matching key for the given key ID.";
 469       decrypt_cb.Run(kNoKey, NULL);
 470       return;
 471     }
 472
 473     crypto::SymmetricKey* decryption_key = key->decryption_key();
 474     decrypted = DecryptData(*encrypted.get(), decryption_key);
 475     if (!decrypted.get()) {
 476       DVLOG(1) << "Decryption failed.";
 477       decrypt_cb.Run(kError, NULL);
 478       return;
 479     }
 480   }
 481
 482   decrypted->set_timestamp(encrypted->timestamp());
 483   decrypted->set_duration(encrypted->duration());
 484   decrypt_cb.Run(kSuccess, decrypted);
 485 }
 486
 487 void AesDecryptor::CancelDecrypt(StreamType stream_type) {
 488   // Decrypt() calls the DecryptCB synchronously so there's nothing to cancel.
 489 }
 490
 491 void AesDecryptor::InitializeAudioDecoder(const AudioDecoderConfig& config,
 492                                           const DecoderInitCB& init_cb) {
 493   // AesDecryptor does not support audio decoding.
 494   init_cb.Run(false);
 495 }
 496
 497 void AesDecryptor::InitializeVideoDecoder(const VideoDecoderConfig& config,
 498                                           const DecoderInitCB& init_cb) {
 499   // AesDecryptor does not support video decoding.
 500   init_cb.Run(false);
 501 }
 502
 503 void AesDecryptor::DecryptAndDecodeAudio(
 504     const scoped_refptr<DecoderBuffer>& encrypted,
 505     const AudioDecodeCB& audio_decode_cb) {
 506   NOTREACHED() << "AesDecryptor does not support audio decoding";
 507 }
 508
 509 void AesDecryptor::DecryptAndDecodeVideo(
 510     const scoped_refptr<DecoderBuffer>& encrypted,
 511     const VideoDecodeCB& video_decode_cb) {
 512   NOTREACHED() << "AesDecryptor does not support video decoding";
 513 }
 514
 515 void AesDecryptor::ResetDecoder(StreamType stream_type) {
 516   NOTREACHED() << "AesDecryptor does not support audio/video decoding";
 517 }
 518
 519 void AesDecryptor::DeinitializeDecoder(StreamType stream_type) {
 520   NOTREACHED() << "AesDecryptor does not support audio/video decoding";
 521 }
 522
 523 bool AesDecryptor::AddDecryptionKey(const std::string& session_id,
 524                                     const std::string& key_id,
 525                                     const std::string& key_string) {
 526   scoped_ptr<DecryptionKey> decryption_key(new DecryptionKey(key_string));
 527   if (!decryption_key->Init()) {
 528     DVLOG(1) << "Could not initialize decryption key.";
 529     return false;
 530   }
 531
 532   base::AutoLock auto_lock(key_map_lock_);
 533   KeyIdToSessionKeysMap::iterator key_id_entry = key_map_.find(key_id);
 534   if (key_id_entry != key_map_.end()) {
 535     key_id_entry->second->Insert(session_id, decryption_key.Pass());
 536     return true;
 537   }
 538
 539   // |key_id| not found, so need to create new entry.
 540   scoped_ptr<SessionIdDecryptionKeyMap> inner_map(
 541       new SessionIdDecryptionKeyMap());
 542   inner_map->Insert(session_id, decryption_key.Pass());
 543   key_map_.add(key_id, inner_map.Pass());
 544   return true;
 545 }
 546
 547 AesDecryptor::DecryptionKey* AesDecryptor::GetKey(
 548     const std::string& key_id) const {
 549   base::AutoLock auto_lock(key_map_lock_);
 550   KeyIdToSessionKeysMap::const_iterator key_id_found = key_map_.find(key_id);
 551   if (key_id_found == key_map_.end())
 552     return NULL;
 553
 554   // Return the key from the "latest" session_id entry.
 555   return key_id_found->second->LatestDecryptionKey();
 556 }
 557
 558 bool AesDecryptor::HasKey(const std::string& session_id,
 559                           const std::string& key_id) {
 560   base::AutoLock auto_lock(key_map_lock_);
 561   KeyIdToSessionKeysMap::const_iterator key_id_found = key_map_.find(key_id);
 562   if (key_id_found == key_map_.end())
 563     return false;
 564
 565   return key_id_found->second->Contains(session_id);
 566 }
 567
 568 void AesDecryptor::DeleteKeysForSession(const std::string& session_id) {
 569   base::AutoLock auto_lock(key_map_lock_);
 570
 571   // Remove all keys associated with |session_id|. Since the data is
 572   // optimized for access in GetKey(), we need to look at each entry in
 573   // |key_map_|.
 574   KeyIdToSessionKeysMap::iterator it = key_map_.begin();
 575   while (it != key_map_.end()) {
 576     it->second->Erase(session_id);
 577     if (it->second->Empty()) {
 578       // Need to get rid of the entry for this key_id. This will mess up the
 579       // iterator, so we need to increment it first.
 580       KeyIdToSessionKeysMap::iterator current = it;
 581       ++it;
 582       key_map_.erase(current);
 583     } else {
 584       ++it;
 585     }
 586   }
 587 }
 588
 589 AesDecryptor::DecryptionKey::DecryptionKey(const std::string& secret)
 590     : secret_(secret) {
 591 }
 592
 593 AesDecryptor::DecryptionKey::~DecryptionKey() {}
 594
 595 bool AesDecryptor::DecryptionKey::Init() {
 596   CHECK(!secret_.empty());
 597   decryption_key_.reset(crypto::SymmetricKey::Import(
 598       crypto::SymmetricKey::AES, secret_));
 599   if (!decryption_key_)
 600     return false;
 601   return true;
 602 }
 603
 604 }  // namespace media