DRM Key Splitting via Dual Nonce Segmentation

Solution Overview

Problem

The traditional Digital Rights Management (DRM) security model is vulnerable because if an attacker gains access to the license manager, they can access the document regardless of the rights manager's decision, making the license manager a single point of failure.

Innovation Solution

The solution involves splitting the secret key into two nonces, where one nonce is delivered to the license manager and the other to the rights manager, requiring both to be breached for document access, using an exclusive-OR function to generate a decryption key for secure access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the secret key is stored in the license manager, then the license manager can efficiently manage document access, but the license manager becomes a single point of failure that attackers can exploit

Engineering Contradiction:

Improvedocument access management efficiencyVSAvoidsecurity against unauthorized access

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The secret key is segmented into two separate nonces: a first nonce stored in the license manager and a second nonce stored in the rights manager. This segmentation eliminates the single point of failure by distributing key components across multiple secure locations, so that compromising one manager does not reveal the complete secret key.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism where the rights manager acts as a mediator between the user and the license manager. The rights manager verifies user credentials and controls whether the second nonce is released, adding an intermediate security layer that prevents direct access to the complete secret key even if the license manager is compromised.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the secret key is split into two nonces distributed to different managers, then security is enhanced by eliminating the single point of failure, but the system complexity increases

Engineering Contradiction:

Improvesecurity against unauthorized accessVSAvoidkey management system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The secret key is segmented into two separate nonces: a first nonce stored in the license manager and a second nonce stored in the rights manager. This segmentation eliminates the single point of failure by distributing key components across multiple secure locations, so that compromising one manager does not reveal the complete secret key.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism where the rights manager acts as a mediator between the user and the license manager. The rights manager verifies user credentials and controls whether the second nonce is released, adding an intermediate security layer that prevents direct access to the complete secret key even if the license manager is compromised.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12141245B2Re-encryption-based digital rights management

Publication Date: 2024.11.12 SONY GROUP CORP

AI summary

Encrypting a document, including: generating first and second nonces; combining the first and second nonces to generate a secret key that is deterministically defined by the first and second nonces; encrypting the document using the secret key to produce an encrypted document; delivering the first nonce to a license manager; and delivering the second nonce to a rights manager.