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- // Copyright 2018 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_ENCRYPTION_PATTERN_H_
- #define MEDIA_BASE_ENCRYPTION_PATTERN_H_
- #include <stdint.h>
- #include "media/base/media_export.h"
- namespace media {
- // CENC 3rd Edition adds pattern encryption, through two new protection
- // schemes: 'cens' (with AES-CTR) and 'cbcs' (with AES-CBC).
- // The pattern applies independently to each 'encrypted' part of the frame (as
- // defined by the relevant subsample entries), and reduces further the
- // actual encryption applied through a repeating pattern of (encrypt:skip)
- // 16 byte blocks. For example, in a (1:9) pattern, the first block is
- // encrypted, and the next nine are skipped. This pattern is applied
- // repeatedly until the end of the last 16-byte block in the subsample.
- // Any remaining bytes are left clear.
- // TODO(jrummell): Use absl::optional<EncryptionPattern> everywhere.
- class MEDIA_EXPORT EncryptionPattern {
- public:
- EncryptionPattern();
- EncryptionPattern(uint32_t crypt_byte_block, uint32_t skip_byte_block);
- EncryptionPattern(const EncryptionPattern& rhs);
- EncryptionPattern& operator=(const EncryptionPattern& rhs);
- ~EncryptionPattern();
- uint32_t crypt_byte_block() const { return crypt_byte_block_; }
- uint32_t skip_byte_block() const { return skip_byte_block_; }
- bool operator==(const EncryptionPattern& other) const;
- bool operator!=(const EncryptionPattern& other) const;
- private:
- // ISO/IEC 23001-7(2016), section 10.3, discussing 'cens' pattern encryption
- // scheme, states "Tracks other than video are protected using whole-block
- // full-sample encryption as specified in 9.7 and hence skip_byte_block
- // SHALL be 0." So patterns where |skip_byte_block| = 0 should be treated
- // as whole-block full-sample encryption.
- uint32_t crypt_byte_block_ = 0; // Count of the encrypted blocks.
- uint32_t skip_byte_block_ = 0; // Count of the unencrypted blocks.
- };
- } // namespace media
- #endif // MEDIA_BASE_ENCRYPTION_PATTERN_H_
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