Index File for Resynchronizing Conditional Access Content
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Solution Overview
Problem
Existing Pay-TV systems face challenges in managing access conditions and transmission key renewal for conditional access content, particularly when content is stored on a user's hard disk, as access conditions during broadcast may differ from those during subsequent use, and existing solutions do not effectively address how to handle this discrepancy for flexible content distribution.
Innovation Solution
A method is introduced where an index file is formed during content broadcast, containing identifiers for control messages and the corresponding content parts, allowing for deferred access by resynchronizing control messages using this index file, which is stored on the user's unit, enabling flexible access conditions independent of the content's initial broadcast mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If content is stored on hard disk for subsequent use, then content availability is improved, but access condition management becomes complex due to differences between broadcast mode and deferred mode conditions
Solution Approach 1:
The patent applies preliminary action by creating an index file during the broadcast mode that pre-records the relationship between control messages and content parts. This index file is stored on the hard disk along with the content, enabling deferred mode access without requiring complex real-time synchronization. The index file contains identifiers that link control messages to specific content portions, allowing the system to retrieve and apply appropriate access conditions when the content is played back later.
2Reliability
If transmission key is renewed regularly for security, then security level is improved, but key management complexity increases for stored content
Solution Approach 1:
The patent applies copying by creating a static copy of the transmission key relationship in the index file during broadcast mode. Instead of requiring the system to track and renew transmission keys dynamically during deferred mode playback, the index file contains recorded identifiers that reference the appropriate control messages. When content is accessed later, the system uses these pre-recorded identifiers to retrieve the correct control messages and their associated keys, eliminating the need for complex real-time key renewal management while maintaining security.
3Adaptability or versatility
If index file is created during broadcast mode, then deferred access flexibility is improved, but storage requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the index file into discrete entries, each corresponding to a specific control message and its associated content part. Rather than storing a single large index structure, the system creates multiple small index entries that can be independently stored and retrieved. Each entry contains a control message identifier and a content position identifier, allowing the system to load only the necessary portions into memory during playback, thereby reducing the active storage requirements while maintaining comprehensive indexing capability.
Data Source
AI summary
A method allows a broadcasted conditional access content accessible at the time of transmission to be also accessible at a later time thanks to intermediate storage on a hard disk of a user unit. The processing method includes the steps of receiving at the user unit a data stream encrypted by at least one control word, at least one control message stream containing the control words, forming an index file, each index comprising an identifier of a control message formed by the extraction of data associated to the control messages and an identifier of the part of the content to which the control message is applied; and, at the time of the deferred processing of the content, extracting at least one part of the control messages and resynchronizing the content with the control messages by the use of the index file, the identifier of the control message allowing the selection of the current control message from a set of control messages at the time of the exploitation of the content identified by the identifier of the part of the content related to this control message.