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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.
#ifndef MEDIA_BASE_DECRYPT_CONFIG_H_
#define MEDIA_BASE_DECRYPT_CONFIG_H_
#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 {
public:
// 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.
// |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.
DecryptConfig(const std::string& key_id,
const std::string& iv,
const std::vector<SubsampleEntry>& subsamples);
~DecryptConfig();
const std::string& key_id() const { return key_id_; }
const std::string& iv() const { return iv_; }
const std::vector<SubsampleEntry>& subsamples() const { return subsamples_; }
private:
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_;
DISALLOW_COPY_AND_ASSIGN(DecryptConfig);
};
} // namespace media
#endif // MEDIA_BASE_DECRYPT_CONFIG_H_
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