Content Handling Device Usage Rule Enforcement via Tagging
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Solution Overview
Problem
Existing digital rights management (DRM) and conditional access (CA) systems face vulnerabilities in enforcing usage rules for media content due to the complexity and attack susceptibility of software implementations, even in trusted execution environments (TEEs).
Innovation Solution
A content handling device and system that distributes the enforcement of usage rules across multiple content transformation modules, applying transformations and tagging operations to ensure compliance, with a usage rule tag checking module to verify that all required transformations have been applied, thereby reducing the processing load and increasing security by preventing tampering attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If usage rules are enforced using software in a trusted execution environment (TEE), then flexibility in content transformation is achieved, but system complexity and vulnerability to attacks increase
Solution Approach 1:
The patent divides the content transformation pipeline into multiple independent transformation modules (e.g., transcoding module, resizing module, format conversion module). Each module operates independently and can be selectively activated based on usage rules, reducing the complexity of any single module while maintaining overall system flexibility. The segmentation allows each module to be simpler and more easily audited.
Solution Approach 2:
The patent introduces a usage rule tag checking module as an intermediary between the content source and sink. This module receives content, checks whether required transformations have been applied by examining usage rule tags, and only allows content to proceed if rules are satisfied. This intermediary approach separates the enforcement logic from the transformation logic, reducing software complexity in the TEE.
2Adaptability or versatility
If usage rules are enforced using software in a TEE, then content transformation flexibility is achieved, but the attack surface increases
Solution Approach 1:
The patent replaces software-based enforcement with hardware-based transformation modules. Each transformation module is implemented as dedicated hardware that physically performs the transformation and simultaneously applies a usage rule tag. This hardware substitution eliminates the software attack surface while maintaining transformation flexibility, as the hardware transformations cannot be manipulated by software attacks.
Solution Approach 2:
The patent implements a feedback mechanism where each transformation module applies a usage rule tag to the content output. The tag checking module then reads these tags and provides feedback on whether all required transformations have been applied. This feedback loop ensures that content can only be output if all usage rules are satisfied, preventing tampering attacks while maintaining flexibility.
3Device complexity
If centralized software enforcement is used, then implementation simplicity is maintained, but processing load and security vulnerability concentrate in one location
Solution Approach 1:
The patent segments the enforcement function across multiple distributed transformation modules, each responsible for a specific transformation type. Instead of centralized software enforcement, each module independently applies its transformation and tags the output. This distribution eliminates the single point of failure while maintaining implementation simplicity through modular design.
Solution Approach 2:
The patent applies local quality by having each transformation module operate with specific local characteristics (e.g., transcoding parameters, resolution settings) tailored to its function. Each module has its own usage rule tags and enforcement logic, allowing customized enforcement at each stage without requiring complex centralized coordination. This localizes the security properties to each module rather than concentrating them centrally.
Data Source
AI summary
A content handling device comprises a plurality of content transformation modules that can define one or more paths from a content source module to a content sink module. The content is associated with one or more usage rules requiring one or more transformations to be applied to the content. To enforce usage rules, each content transformation module is configured to receive the content, apply a transformation to the content in accordance with the usage rules and apply a tagging operation corresponding to the transformation to the content. In some embodiments output of the content by the content sink module is prevented if all tagging operations corresponding to the usage rules have not been applied. While in some embodiments usage rule tags corresponding to the usage rules are embedded locally at the content handling device, the disclosure also extends to a content distribution system with a usage rule tag embedding functionality.