media/cdm/aes_decryptor.h

   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 #ifndef MEDIA_CRYPTO_AES_DECRYPTOR_H_
   6 #define MEDIA_CRYPTO_AES_DECRYPTOR_H_
   7
   8 #include <set>
   9 #include <string>
  10
  11 #include "base/basictypes.h"
  12 #include "base/containers/scoped_ptr_hash_map.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "base/synchronization/lock.h"
  16 #include "media/base/cdm_context.h"
  17 #include "media/base/decryptor.h"
  18 #include "media/base/media_export.h"
  19 #include "media/base/media_keys.h"
  20
  21 class GURL;
  22
  23 namespace crypto {
  24 class SymmetricKey;
  25 }
  26
  27 namespace media {
  28
  29 // Decrypts an AES encrypted buffer into an unencrypted buffer. The AES
  30 // encryption must be CTR with a key size of 128bits.
  31 class MEDIA_EXPORT AesDecryptor : public MediaKeys,
  32                                   public CdmContext,
  33                                   public Decryptor {
  34  public:
  35   AesDecryptor(const GURL& security_origin,
  36                const SessionMessageCB& session_message_cb,
  37                const SessionClosedCB& session_closed_cb,
  38                const SessionKeysChangeCB& session_keys_change_cb);
  39   ~AesDecryptor() override;
  40
  41   // MediaKeys implementation.
  42   void SetServerCertificate(const uint8* certificate_data,
  43                             int certificate_data_length,
  44                             scoped_ptr<SimpleCdmPromise> promise) override;
  45   void CreateSessionAndGenerateRequest(
  46       SessionType session_type,
  47       EmeInitDataType init_data_type,
  48       const uint8* init_data,
  49       int init_data_length,
  50       scoped_ptr<NewSessionCdmPromise> promise) override;
  51   void LoadSession(SessionType session_type,
  52                    const std::string& session_id,
  53                    scoped_ptr<NewSessionCdmPromise> promise) override;
  54   void UpdateSession(const std::string& session_id,
  55                      const uint8* response,
  56                      int response_length,
  57                      scoped_ptr<SimpleCdmPromise> promise) override;
  58   void CloseSession(const std::string& session_id,
  59                     scoped_ptr<SimpleCdmPromise> promise) override;
  60   void RemoveSession(const std::string& session_id,
  61                      scoped_ptr<SimpleCdmPromise> promise) override;
  62   CdmContext* GetCdmContext() override;
  63
  64   // CdmContext implementation.
  65   Decryptor* GetDecryptor() override;
  66   int GetCdmId() const override;
  67
  68   // Decryptor implementation.
  69   void RegisterNewKeyCB(StreamType stream_type,
  70                         const NewKeyCB& key_added_cb) override;
  71   void Decrypt(StreamType stream_type,
  72                const scoped_refptr<DecoderBuffer>& encrypted,
  73                const DecryptCB& decrypt_cb) override;
  74   void CancelDecrypt(StreamType stream_type) override;
  75   void InitializeAudioDecoder(const AudioDecoderConfig& config,
  76                               const DecoderInitCB& init_cb) override;
  77   void InitializeVideoDecoder(const VideoDecoderConfig& config,
  78                               const DecoderInitCB& init_cb) override;
  79   void DecryptAndDecodeAudio(const scoped_refptr<DecoderBuffer>& encrypted,
  80                              const AudioDecodeCB& audio_decode_cb) override;
  81   void DecryptAndDecodeVideo(const scoped_refptr<DecoderBuffer>& encrypted,
  82                              const VideoDecodeCB& video_decode_cb) override;
  83   void ResetDecoder(StreamType stream_type) override;
  84   void DeinitializeDecoder(StreamType stream_type) override;
  85
  86  private:
  87   // TODO(fgalligan): Remove this and change KeyMap to use crypto::SymmetricKey
  88   // as there are no decryptors that are performing an integrity check.
  89   // Helper class that manages the decryption key.
  90   class DecryptionKey {
  91    public:
  92     explicit DecryptionKey(const std::string& secret);
  93     ~DecryptionKey();
  94
  95     // Creates the encryption key.
  96     bool Init();
  97
  98     crypto::SymmetricKey* decryption_key() { return decryption_key_.get(); }
  99
 100    private:
 101     // The base secret that is used to create the decryption key.
 102     const std::string secret_;
 103
 104     // The key used to decrypt the data.
 105     scoped_ptr<crypto::SymmetricKey> decryption_key_;
 106
 107     DISALLOW_COPY_AND_ASSIGN(DecryptionKey);
 108   };
 109
 110   // Keep track of the keys for a key ID. If multiple sessions specify keys
 111   // for the same key ID, then the last key inserted is used. The structure is
 112   // optimized so that Decrypt() has fast access, at the cost of slow deletion
 113   // of keys when a session is released.
 114   class SessionIdDecryptionKeyMap;
 115
 116   // Key ID <-> SessionIdDecryptionKeyMap map.
 117   typedef base::ScopedPtrHashMap<std::string, SessionIdDecryptionKeyMap>
 118       KeyIdToSessionKeysMap;
 119
 120   // Creates a DecryptionKey using |key_string| and associates it with |key_id|.
 121   // Returns true if successful.
 122   bool AddDecryptionKey(const std::string& session_id,
 123                         const std::string& key_id,
 124                         const std::string& key_string);
 125
 126   // Gets a DecryptionKey associated with |key_id|. The AesDecryptor still owns
 127   // the key. Returns NULL if no key is associated with |key_id|.
 128   DecryptionKey* GetKey(const std::string& key_id) const;
 129
 130   // Determines if |key_id| is already specified for |session_id|.
 131   bool HasKey(const std::string& session_id, const std::string& key_id);
 132
 133   // Deletes all keys associated with |session_id|.
 134   void DeleteKeysForSession(const std::string& session_id);
 135
 136   // Callbacks for firing session events.
 137   SessionMessageCB session_message_cb_;
 138   SessionClosedCB session_closed_cb_;
 139   SessionKeysChangeCB session_keys_change_cb_;
 140
 141   // Since only Decrypt() is called off the renderer thread, we only need to
 142   // protect |key_map_|, the only member variable that is shared between
 143   // Decrypt() and other methods.
 144   KeyIdToSessionKeysMap key_map_;  // Protected by |key_map_lock_|.
 145   mutable base::Lock key_map_lock_;  // Protects the |key_map_|.
 146
 147   // Keeps track of current valid sessions.
 148   std::set<std::string> valid_sessions_;
 149
 150   // Make session ID unique per renderer by making it static. Session
 151   // IDs seen by the app will be "1", "2", etc.
 152   static uint32 next_session_id_;
 153
 154   NewKeyCB new_audio_key_cb_;
 155   NewKeyCB new_video_key_cb_;
 156
 157   // Protect |new_audio_key_cb_| and |new_video_key_cb_| as they are set on the
 158   // main thread but called on the media thread.
 159   mutable base::Lock new_key_cb_lock_;
 160
 161   DISALLOW_COPY_AND_ASSIGN(AesDecryptor);
 162 };
 163
 164 }  // namespace media
 165
 166 #endif  // MEDIA_CRYPTO_AES_DECRYPTOR_H_