Playback Apparatus Key Selection for Mixed DRM Content

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Solution Overview

Problem

Playback systems struggle to distinguish and appropriately decrypt content protected by conventional methods and DRM on the same medium, leading to playback issues when both types of content coexist.

Innovation Solution

A playback terminal and method that includes a license obtaining unit, content key obtaining unit, key selection unit, and decryption unit to determine whether to use a medium key or a DRM license for decryption, ensuring correct playback of both types of content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the player uses the medium key to decrypt content, then conventional copy-protected content can be played back, but DRM-encrypted content cannot be decrypted

Engineering Contradiction:

Improveplayback reliabilityVSAvoidcontent format compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically switches between medium key decryption and license key decryption based on the content type. The key selection unit determines which decryption method to use by checking key selection information, making the decryption approach flexible rather than fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the decryption parameter (key type) based on the content being processed. By introducing key selection information that indicates the encryption type, the system can switch between using medium keys for conventional content and license keys for DRM content.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the player searches for a license for conventional copy-protected content, then DRM content can be decrypted, but conventional content cannot be played back because no corresponding license exists

Engineering Contradiction:

Improvecontent format compatibilityVSAvoidplayback reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary identification of the content type and pre-determines the appropriate decryption method before attempting decryption. The key selection unit checks key selection information in advance to decide whether to use medium key or license key decryption, avoiding unnecessary license searches for conventional content.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If the player attempts to decrypt both types of content with the same method, then decryption simplicity is maintained, but playback functionality is lost for one of the content types

Engineering Contradiction:

Improvedecryption operation simplicityVSAvoidcontent playback functionality

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The decryption process is segmented into two distinct paths: one for conventional content using medium keys and another for DRM content using license keys. The key selection unit directs the appropriate decryption method based on key selection information, maintaining operational simplicity while ensuring both content types can be decrypted.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7715558B2Encrypted-content recording medium, playback apparatus, and playback method

Publication Date: 2010.05.11 PANASONIC HOLDINGS CORP

AI summary

An encrypted content playback apparatus and a playback method are suitable for content playback from a recording medium having stored thereon both content that is subject to conventional copy protection and content to which DRAM is applied. The recording medium stores information indicating, for each content, whether the content is content subject to conventional copy protection or content to which DRAM is applied. Based on this information, the playback apparatus determines the key to use to decrypt the content.