Decommissioned Rights Management Server Content Decryption

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Solution Overview

Problem

Content owners and developers face challenges in controlling digital content distribution within organizations, as existing rights management systems lack effective mechanisms to enforce usage restrictions and prevent unauthorized access and redistribution, especially after content is distributed.

Innovation Solution

A method is introduced where content is encrypted with a cryptographic key, and the decryption key is encrypted using a public key of a rights management server, ensuring only the server can decrypt and issue licenses, with a notification system for decommissioned servers to prevent further licensing and allow content decryption for removal of protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If digital content is distributed to users, then content accessibility and usage flexibility improve, but control over content rendering and prevention of unauthorized redistribution deteriorate

Engineering Contradiction:

Improvecontent accessibilityVSAvoidcontrol over content rendering

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The content is encrypted with a cryptographic key before distribution, and the decryption key is encrypted with the rights management server's public key in advance. This preliminary encryption ensures that even after distribution, the content remains protected and can only be rendered by authorized users who can obtain the decryption key from the rights management server.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A rights management server acts as an intermediary between the content and users. The server holds the private key needed to decrypt the encrypted decryption key, thereby controlling who can access and render the content. This intermediary mechanism maintains reliability of content control while allowing broad distribution.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If a rights management server is decommissioned, then system complexity and security risks reduce, but ability to issue licenses and maintain content protection deteriorates

Engineering Contradiction:

Improvesystem complexityVSAvoidlicense issuance capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Before the rights management server is decommissioned, all necessary decryption keys are distributed to authorized users through licenses. This preliminary distribution ensures that even after the server is decommissioned, users who received licenses can continue to render content without requiring further server interaction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The decryption key is copied and distributed to authorized users through licensed copies. Each user receives a license containing the decryption key encrypted with their public key, allowing them to independently decrypt and render content without ongoing dependency on the rights management server.

Inventive Principle:

Principle #26Copying

3Ease of operation

If decryption keys are made accessible to users, then content rendering capability improves, but risk of unauthorized access and redistribution increases

Engineering Contradiction:

Improvecontent rendering capabilityVSAvoidunauthorized access risk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The rights management server acts as a trusted intermediary that securely distributes decryption keys only to authorized users through licenses. The server verifies user credentials and issues licenses containing decryption keys encrypted with the user's public key, ensuring that only authorized users can access the content while maintaining ease of rendering for those users.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Different users receive different decryption keys tailored to their specific authorization levels and needs. Each license contains a decryption key that is locally encrypted for that specific user, allowing customized access control where each user has the exact rendering capability they are authorized for, no more and no less.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7570768B2Systems, structures, and methods for decrypting encrypted digital content when a rights management server has been decommissioned

Publication Date: 2009.08.04 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

A method is disclosed for rendering content encrypted according to a cryptographic key, where the content has corresponding rights data including a decryption key (KD) for decrypting the encrypted content, and where (KD) in the rights data is encrypted according to a public key of a rights management (RM) server (PU-RM) to result in (PU-RM(KD)). The RM server normally delivers (KD) within a license, but upon being decommissioned can no longer issue such license. In the method, a notification is received that the RM server has been decommissioned, and thereafter an attempt is made to render a piece of content. Such content is determined to be protected to the decommissioned RM server, and a request is sent to the decommissioned RM server for the content key (KD) for the content rather than any license. Thereafter (KD) is received from the decommissioned RM server.