Selective Video Payload Encryption for MPEG Frame Tracking
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Solution Overview
Problem
Existing digital rights management systems encrypt entire video data files, making it impossible to distinguish frame boundaries, which is problematic for selective decryption and distribution of video content, especially when using formats like MPEG 2 where header data is scrambled.
Innovation Solution
The system selectively encrypts only the payload portion of the video data, leaving the format identifying portion unencrypted, allowing frame boundaries to be identified and enabling conventional decoders to correctly track frames without decrypting the header data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encryption is applied to the entire video data file, then security and copyright protection are improved, but frame boundary identification becomes impossible and selective decryption cannot be performed
Solution Approach 1:
The video data is segmented into two distinct parts: format identifying portions (headers) and payload portions. Only the payload portions are encrypted while the format identifying portions remain unencrypted. This segmentation allows frame boundaries to be identified through the unencrypted headers while the payload content remains protected by encryption.
Solution Approach 2:
Different parts of the video data are treated with different encryption approaches. The format identifying portions are left unencrypted to maintain their structural identification function, while the payload portions are encrypted to protect the actual content. This local differentiation of encryption quality resolves the contradiction between security and frame boundary identification.
2Reliability
If encryption is applied to the entire video data file, then copyright protection is improved, but selective distribution of video subsections becomes difficult
Solution Approach 1:
The video stream is divided into independently addressable segments at the frame level, with each frame's payload being separately encryptable. This allows the content owner to selectively decrypt and distribute specific frames or frame ranges to different recipients, providing versatile selective distribution while maintaining overall copyright protection through encryption of the payload portions.
Solution Approach 2:
The encryption system is made dynamic by allowing selective decryption of different payload portions based on distribution needs. The unencrypted format identifying portions remain constant and available for all operations, while the encrypted payload portions can be selectively decrypted and redistributed, providing adaptability for various distribution scenarios.
3Reliability
If header data is encrypted, then overall security is improved, but conventional MPEG 2 decoders cannot correctly track frame boundaries
Solution Approach 1:
The encryption approach applies different treatment to different parts of the data structure: format identifying portions (headers) are left unencrypted to preserve their function for frame boundary identification, while payload portions are encrypted for security. This local quality differentiation ensures that conventional decoders can correctly track frame boundaries through unencrypted headers while the actual content remains secure.
Data Source
AI summary
A data encryption apparatus operable to apply encryption to input data having at least a format identifying portion and a payload portion comprises means for discriminating between the format identifying portion of the input data and the payload portion of the input data; and means for selectively applying encryption to the input data in dependence upon an output of the discriminating means so as to encrypt at least a part of the payload portion of the input data but not to encrypt the format identifying portion. A corresponding decryption apparatus is also provided.