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 #include <vector>
  11
  12 #include "base/basictypes.h"
  13 #include "base/containers/scoped_ptr_hash_map.h"
  14 #include "base/memory/ref_counted.h"
  15 #include "base/memory/scoped_ptr.h"
  16 #include "base/synchronization/lock.h"
  17 #include "media/base/cdm_context.h"
  18 #include "media/base/decryptor.h"
  19 #include "media/base/media_export.h"
  20 #include "media/base/media_keys.h"
  21
  22 class GURL;
  23
  24 namespace crypto {
  25 class SymmetricKey;
  26 }
  27
  28 namespace media {
  29
  30 // Decrypts an AES encrypted buffer into an unencrypted buffer. The AES
  31 // encryption must be CTR with a key size of 128bits.
  32 class MEDIA_EXPORT AesDecryptor : public MediaKeys,
  33                                   public CdmContext,
  34                                   public Decryptor {
  35  public:
  36   AesDecryptor(const GURL& security_origin,
  37                const SessionMessageCB& session_message_cb,
  38                const SessionClosedCB& session_closed_cb,
  39                const SessionKeysChangeCB& session_keys_change_cb);
  40   ~AesDecryptor() override;
  41
  42   // MediaKeys implementation.
  43   void SetServerCertificate(const std::vector<uint8_t>& certificate,
  44                             scoped_ptr<SimpleCdmPromise> promise) override;
  45   void CreateSessionAndGenerateRequest(
  46       SessionType session_type,
  47       EmeInitDataType init_data_type,
  48       const std::vector<uint8_t>& init_data,
  49       scoped_ptr<NewSessionCdmPromise> promise) override;
  50   void LoadSession(SessionType session_type,
  51                    const std::string& session_id,
  52                    scoped_ptr<NewSessionCdmPromise> promise) override;
  53   void UpdateSession(const std::string& session_id,
  54                      const std::vector<uint8_t>& response,
  55                      scoped_ptr<SimpleCdmPromise> promise) override;
  56   void CloseSession(const std::string& session_id,
  57                     scoped_ptr<SimpleCdmPromise> promise) override;
  58   void RemoveSession(const std::string& session_id,
  59                      scoped_ptr<SimpleCdmPromise> promise) override;
  60   CdmContext* GetCdmContext() override;
  61
  62   // CdmContext implementation.
  63   Decryptor* GetDecryptor() override;
  64   int GetCdmId() const override;
  65
  66   // Decryptor implementation.
  67   void RegisterNewKeyCB(StreamType stream_type,
  68                         const NewKeyCB& key_added_cb) override;
  69   void Decrypt(StreamType stream_type,
  70                const scoped_refptr<DecoderBuffer>& encrypted,
  71                const DecryptCB& decrypt_cb) override;
  72   void CancelDecrypt(StreamType stream_type) override;
  73   void InitializeAudioDecoder(const AudioDecoderConfig& config,
  74                               const DecoderInitCB& init_cb) override;
  75   void InitializeVideoDecoder(const VideoDecoderConfig& config,
  76                               const DecoderInitCB& init_cb) override;
  77   void DecryptAndDecodeAudio(const scoped_refptr<DecoderBuffer>& encrypted,
  78                              const AudioDecodeCB& audio_decode_cb) override;
  79   void DecryptAndDecodeVideo(const scoped_refptr<DecoderBuffer>& encrypted,
  80                              const VideoDecodeCB& video_decode_cb) override;
  81   void ResetDecoder(StreamType stream_type) override;
  82   void DeinitializeDecoder(StreamType stream_type) override;
  83
  84  private:
  85   // TODO(fgalligan): Remove this and change KeyMap to use crypto::SymmetricKey
  86   // as there are no decryptors that are performing an integrity check.
  87   // Helper class that manages the decryption key.
  88   class DecryptionKey {
  89    public:
  90     explicit DecryptionKey(const std::string& secret);
  91     ~DecryptionKey();
  92
  93     // Creates the encryption key.
  94     bool Init();
  95
  96     crypto::SymmetricKey* decryption_key() { return decryption_key_.get(); }
  97
  98    private:
  99     // The base secret that is used to create the decryption key.
 100     const std::string secret_;
 101
 102     // The key used to decrypt the data.
 103     scoped_ptr<crypto::SymmetricKey> decryption_key_;
 104
 105     DISALLOW_COPY_AND_ASSIGN(DecryptionKey);
 106   };
 107
 108   // Keep track of the keys for a key ID. If multiple sessions specify keys
 109   // for the same key ID, then the last key inserted is used. The structure is
 110   // optimized so that Decrypt() has fast access, at the cost of slow deletion
 111   // of keys when a session is released.
 112   class SessionIdDecryptionKeyMap;
 113
 114   // Key ID <-> SessionIdDecryptionKeyMap map.
 115   typedef base::ScopedPtrHashMap<std::string,
 116                                  scoped_ptr<SessionIdDecryptionKeyMap>>
 117       KeyIdToSessionKeysMap;
 118
 119   // Creates a DecryptionKey using |key_string| and associates it with |key_id|.
 120   // Returns true if successful.
 121   bool AddDecryptionKey(const std::string& session_id,
 122                         const std::string& key_id,
 123                         const std::string& key_string);
 124
 125   // Gets a DecryptionKey associated with |key_id|. The AesDecryptor still owns
 126   // the key. Returns NULL if no key is associated with |key_id|.
 127   DecryptionKey* GetKey_Locked(const std::string& key_id) const;
 128
 129   // Determines if |key_id| is already specified for |session_id|.
 130   bool HasKey(const std::string& session_id, const std::string& key_id);
 131
 132   // Deletes all keys associated with |session_id|.
 133   void DeleteKeysForSession(const std::string& session_id);
 134
 135   // Callbacks for firing session events.
 136   SessionMessageCB session_message_cb_;
 137   SessionClosedCB session_closed_cb_;
 138   SessionKeysChangeCB session_keys_change_cb_;
 139
 140   // Since only Decrypt() is called off the renderer thread, we only need to
 141   // protect |key_map_|, the only member variable that is shared between
 142   // Decrypt() and other methods.
 143   KeyIdToSessionKeysMap key_map_;  // Protected by |key_map_lock_|.
 144   mutable base::Lock key_map_lock_;  // Protects the |key_map_|.
 145
 146   // Keeps track of current valid sessions.
 147   std::set<std::string> valid_sessions_;
 148
 149   // Make session ID unique per renderer by making it static. Session
 150   // IDs seen by the app will be "1", "2", etc.
 151   static uint32_t next_session_id_;
 152
 153   NewKeyCB new_audio_key_cb_;
 154   NewKeyCB new_video_key_cb_;
 155
 156   // Protect |new_audio_key_cb_| and |new_video_key_cb_| as they are set on the
 157   // main thread but called on the media thread.
 158   mutable base::Lock new_key_cb_lock_;
 159
 160   DISALLOW_COPY_AND_ASSIGN(AesDecryptor);
 161 };
 162
 163 }  // namespace media
 164
 165 #endif  // MEDIA_CRYPTO_AES_DECRYPTOR_H_