chromecast/public/media/cast_decrypt_config.h

   1 // Copyright 2015 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 CHROMECAST_PUBLIC_MEDIA_CAST_DECRYPT_CONFIG_H_
   6 #define CHROMECAST_PUBLIC_MEDIA_CAST_DECRYPT_CONFIG_H_
   7
   8 #include <stdint.h>
   9 #include <string>
  10 #include <vector>
  11
  12 namespace chromecast {
  13 namespace media {
  14
  15 // The Common Encryption spec provides for subsample encryption, where portions
  16 // of a sample are set in cleartext. A SubsampleEntry specifies the number of
  17 // clear and encrypted bytes in each subsample. For decryption, all of the
  18 // encrypted bytes in a sample should be considered a single logical stream,
  19 // regardless of how they are divided into subsamples, and the clear bytes
  20 // should not be considered as part of decryption. This is logically equivalent
  21 // to concatenating all 'cypher_bytes' portions of subsamples, decrypting that
  22 // result, and then copying each byte from the decrypted block over the
  23 // position of the corresponding encrypted byte.
  24 struct SubsampleEntry {
  25   SubsampleEntry() : clear_bytes(0), cypher_bytes(0) {}
  26   SubsampleEntry(uint32_t clear_bytes, uint32_t cypher_bytes)
  27       : clear_bytes(clear_bytes), cypher_bytes(cypher_bytes) {}
  28   uint32_t clear_bytes;
  29   uint32_t cypher_bytes;
  30 };
  31
  32 // Contains all metadata needed to decrypt a media sample.
  33 class CastDecryptConfig {
  34  public:
  35   virtual ~CastDecryptConfig() {}
  36
  37   // Returns the ID for this sample's decryption key.
  38   virtual const std::string& key_id() const = 0;
  39
  40   // Returns the initialization vector as defined by the encryption format.
  41   virtual const std::string& iv() const = 0;
  42
  43   // Returns the clear and encrypted portions of the sample as described above.
  44   virtual const std::vector<SubsampleEntry>& subsamples() const = 0;
  45 };
  46
  47 }  // namespace media
  48 }  // namespace chromecast
  49
  50 #endif  // CHROMECAST_PUBLIC_MEDIA_CAST_DECRYPT_CONFIG_H_