Secure System Time Synchronization for Digital Rights Management
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Solution Overview
Problem
There is a need for a secure method to provide system time in digital multimedia content distribution systems to enforce time-based usage rules for digital rights management, as existing solutions are vulnerable to tampering and do not effectively prevent unauthorized access after a specified period.
Innovation Solution
A secure system time message is broadcasted to subscriber devices, which includes a time sequence number to authenticate and synchronize the local clock reference, ensuring legitimate system time is used to enforce usage rules, thereby preventing unauthorized access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a system time reference is provided to subscriber devices, then time-based usage rules can be enforced, but the system becomes vulnerable to tampering and unauthorized access
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the local clock reference with the system time reference before content delivery begins. This ensures that the subscriber device already has an accurate time baseline when receiving encrypted content, enabling proper enforcement of time-based usage rules from the outset and preventing tampering attempts.
Solution Approach 2:
The patent introduces an intermediary verification mechanism where the security device mediates between the system time reference and the local clock reference. The security device verifies the legitimacy of the system time reference and manages the synchronization process, acting as a trusted intermediary that prevents unauthorized time manipulation while enabling legitimate time-based access control.
2Measurement precision
If the local clock reference is synchronized with system time, then usage rules are enforced accurately, but the system becomes vulnerable to time manipulation attacks
Solution Approach 1:
The patent performs preliminary synchronization of the local clock reference with the system time reference before content delivery. This preliminary action establishes a trusted time baseline that is verified by the security device, ensuring accurate time measurement for usage rule enforcement while preventing subsequent manipulation attacks.
Solution Approach 2:
The patent implements a feedback mechanism where the security device continuously monitors and verifies the system time reference legitimacy. This feedback loop ensures that any time manipulation attempts are detected and rejected, maintaining both time synchronization accuracy and protection against manipulation attacks simultaneously.
Data Source
AI summary
The present invention discloses a system and method for providing a secured system time reference to a subscriber device, e.g., a set top box or a receiver. In one embodiment, the system time reference is provided in a secure system time message that is broadcasted to a plurality of subscriber devices. Each subscriber device has a security device or software application that is capable of determining whether the received system time reference is legitimate. If the system time reference is determined to be legitimate, a local time reference is synchronized with said received system time reference.