Recording Medium Device Content-Specific Revocation for Unauthorized Access
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Solution Overview
Problem
The existing Advanced Access Content System (AACS) for Blu-ray Discs is inadequate in allowing content providers to flexibly manage unauthorized use of digital contents, particularly for high-value 'Early Window Contents', as it requires a lengthy process to revoke invalid device keys, leading to delayed protection against unauthorized playback.
Innovation Solution
A content distribution system that includes a recording medium device capable of storing revocation information specific to each content provider, allowing for flexible management of terminal devices, where the recording medium device determines whether a terminal device is restricted based on content-specific attributes, preventing unauthorized use by withholding necessary usage information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the AACS system uses MKB to revoke invalid device keys, then unauthorized device keys are prevented from accessing contents, but content providers cannot flexibly restrict specific terminal devices for their own contents
Solution Approach 1:
The patent segments the revocation mechanism by introducing content-specific revocation information that operates independently from the global MKB system. Each content can have its own list of restricted terminal devices, allowing content providers to selectively control access to their specific contents while maintaining compatibility with the overall AACS framework.
Solution Approach 2:
The patent adds a new dimension to the revocation system by introducing content-specific device restriction lists alongside the traditional MKB-based global revocation mechanism. This creates a multi-layered approach where restrictions can be applied both globally (via MKB) and individually per content (via content-specific device restriction information), enabling flexible content-provider-specific control.
2Reliability
If the system restricts terminal devices based on leaked device keys in MKB, then security is maintained, but the process is lengthy and delays protection against unauthorized playback
Solution Approach 1:
The patent enables preliminary action by allowing content providers to pre-identify and restrict specific terminal devices before unauthorized playback occurs. By maintaining content-specific device restriction lists, providers can immediately block suspected devices without waiting for the lengthy MKB update process, thus preventing unauthorized playback in advance.
Solution Approach 2:
The patent allows the system to skip the lengthy MKB update process for urgent restrictions by directly applying content-specific device restriction information. This enables rapid response to security threats by immediately restricting specific terminal devices without going through the time-consuming global revocation procedure.
3Adaptability or versatility
If the AACS system applies device key revocation globally through MKB, then unauthorized devices are blocked, but legitimate devices cannot access content when the content provider needs flexible control
Solution Approach 1:
The patent applies local quality by implementing revocation restrictions at the content level rather than globally. Each content can have its own device restriction list tailored to the specific needs of the content provider, allowing legitimate devices to access different contents based on individual content policies while maintaining security where needed.
Solution Approach 2:
The patent introduces dynamics by making device access rights flexible and content-specific. Instead of static global revocation, the system dynamically determines device access based on content-specific restriction lists, allowing content providers to adjust access permissions flexibly for different contents while maintaining ease of operation through automated verification.
Data Source
AI summary
When the terminal device attempts to use a special content, which has an attribute including information distinguishing the special content from regular contents and which is stored in the recording medium device, the recording medium device refers to the revocation information indicating terminal devices restricted from using the special content. When the recording medium device determines the terminal device as a terminal device to be restricted from using the special content based on the terminal identifying information of the terminal device, the usage information output unit of the recording medium device does not transmit the necessary information for using the special content to the terminal device.