blob: 6dbc4e3fa34262ed9811190a46b6c753c0a8d5cd [file] [log] [blame]
// 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 <string>
#include <vector>
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "media/base/media_export.h"
namespace media {
// The Common Encryption spec provides for subsample encryption, where portions
// of a sample are set in cleartext. A SubsampleEntry specifies the number of
// clear and encrypted bytes in each subsample. For decryption, all of the
// encrypted bytes in a sample should be considered a single logical stream,
// regardless of how they are divided into subsamples, and the clear bytes
// should not be considered as part of decryption. This is logically equivalent
// to concatenating all 'cypher_bytes' portions of subsamples, decrypting that
// result, and then copying each byte from the decrypted block over the
// position of the corresponding encrypted byte.
struct SubsampleEntry {
uint32 clear_bytes;
uint32 cypher_bytes;
// 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. Or must be
// empty which signals an unencrypted frame.
// |data_offset| is the amount of data that should be discarded from the
// head of the sample buffer before applying subsample information. A
// decrypted buffer will be shorter than an encrypted buffer by this amount.
// |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.
// |data_offset| is applied before |subsamples|.
DecryptConfig(const std::string& key_id,
const std::string& iv,
#if !defined(__LB_SHELL__) && !defined(COBALT)
const int data_offset,
#endif // !defined(__LB_SHELL__) && !defined(COBALT)
const std::vector<SubsampleEntry>& subsamples);
const std::string& key_id() const { return key_id_; }
const std::string& iv() const { return iv_; }
#if !defined(__LB_SHELL__) && !defined(COBALT)
int data_offset() const { return data_offset_; }
#endif // !defined(__LB_SHELL__) && !defined(COBALT)
const std::vector<SubsampleEntry>& subsamples() const { return subsamples_; }
const std::string key_id_;
// Initialization vector.
const std::string iv_;
#if !defined(__LB_SHELL__) && !defined(COBALT)
// TODO(fgalligan): Remove |data_offset_| if there is no plan to use it in
// the future.
// Amount of data to be discarded before applying subsample information.
const int data_offset_;
#endif // !defined(__LB_SHELL__) && !defined(COBALT)
// Subsample information. May be empty for some formats, meaning entire frame
// (less data ignored by data_offset_) is encrypted.
const std::vector<SubsampleEntry> subsamples_;
} // namespace media