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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stdint.h>
#include <iosfwd>
#include <memory>
#include <string>
#include <vector>
#include "base/macros.h"
#include "base/optional.h"
#include "media/base/encryption_pattern.h"
#include "media/base/media_export.h"
#include "media/base/subsample_entry.h"
namespace media {
// The encryption mode. The definitions are from ISO/IEC 23001-7:2016.
// TODO( Merge this with existing media::EncryptionScheme.
enum class EncryptionMode {
kUnencrypted = 0,
kCenc, // 'cenc' subsample encryption using AES-CTR mode.
kCbcs, // 'cbcs' pattern encryption using AES-CBC mode.
kMaxValue = kCbcs
// Contains all information that a decryptor needs to decrypt a media sample.
class MEDIA_EXPORT DecryptConfig {
// Keys are always 128 bits.
static const int kDecryptionKeySize = 16;
// |key_id| is the ID that references the decryption key for this sample.
// |iv| is the initialization vector defined by the encrypted format.
// Currently |iv| must be 16 bytes as defined by WebM and ISO. It must
// be provided.
// |subsamples| defines the clear and encrypted portions of the sample as
// described above. A decrypted buffer will be equal in size to the sum
// of the subsample sizes.
// |encryption_pattern| is the pattern used ('cbcs' only). It is optional
// as Common encryption of MPEG-2 transport streams v1 (23009-1:2014)
// does not specify patterns for cbcs encryption mode. The pattern is
// assumed to be 1:9 for video. Tracks other than video are protected
// using whole-block full-sample encryption (pattern 0:0 or unspecified).
static std::unique_ptr<DecryptConfig> CreateCencConfig(
const std::string& key_id,
const std::string& iv,
const std::vector<SubsampleEntry>& subsamples);
static std::unique_ptr<DecryptConfig> CreateCbcsConfig(
const std::string& key_id,
const std::string& iv,
const std::vector<SubsampleEntry>& subsamples,
base::Optional<EncryptionPattern> encryption_pattern);
DecryptConfig(const EncryptionMode& encryption_mode,
const std::string& key_id,
const std::string& iv,
const std::vector<SubsampleEntry>& subsamples,
base::Optional<EncryptionPattern> encryption_pattern);
const std::string& key_id() const { return key_id_; }
const std::string& iv() const { return iv_; }
const std::vector<SubsampleEntry>& subsamples() const { return subsamples_; }
const EncryptionMode& encryption_mode() const { return encryption_mode_; }
const base::Optional<EncryptionPattern>& encryption_pattern() const {
return encryption_pattern_;
std::unique_ptr<DecryptConfig> Clone() const;
// Makes a new config which has the same configuration options (mode, pattern)
// while providing a new vector of subsamples and initialization vector.
std::unique_ptr<DecryptConfig> CopyNewSubsamplesIV(
const std::vector<SubsampleEntry>& subsamples,
const std::string& iv);
// Returns whether this config has EncryptionPattern set or not.
bool HasPattern() const;
// Returns true if all fields in |config| match this config.
bool Matches(const DecryptConfig& config) const;
// Prints to std::ostream.
std::ostream& Print(std::ostream& os) const;
DecryptConfig(const DecryptConfig& other);
const EncryptionMode encryption_mode_;
const std::string key_id_;
// Initialization vector.
const std::string iv_;
// Subsample information. May be empty for some formats, meaning entire frame
// (less data ignored by data_offset_) is encrypted.
const std::vector<SubsampleEntry> subsamples_;
// Only specified if |encryption_mode_| requires a pattern.
base::Optional<EncryptionPattern> encryption_pattern_;
inline std::ostream& operator<<(std::ostream& os,
const media::DecryptConfig& obj) {
return obj.Print(os);
} // namespace media