Reversible Transform for Image DRM Protection

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Solution Overview

Problem

Existing digital rights management (DRM) solutions for images and video are vulnerable to attacks as they decode and decompress media files, allowing attackers to access plaintext versions, which can be copied or hacked.

Innovation Solution

Applying a reversible transform to images before compression, ensuring that the transform remains after decoding and decompression, and using an inverse transform at the display hardware to prevent plaintext exposure, combined with additional security measures like key delivery and optional encoding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If media files are decoded and decompressed for playback, then the media can be displayed to consumers, but attackers can access plaintext versions and copy or hack the content

Engineering Contradiction:

Improvemedia playback capabilityVSAvoidvulnerability to attacks

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A reversible transform is applied to the media content before compression and encoding. This transform modifies the plaintext data in advance, so that when the media is decoded and decompressed during playback, the output is transformed data rather than the original plaintext. The transform is designed to be reversible only with specific key material, preventing attackers from obtaining usable plaintext versions during any stage of the playback pipeline.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The reversible transform acts as an intermediary layer between the original plaintext media and the compressed bitstream. This intermediate transformed version is what gets encoded and delivered to consumers. The transform creates a barrier that prevents direct access to the original plaintext, requiring additional key material and processing steps that are not available in traditional DRM approaches.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a reversible transform is applied before compression, then plaintext vulnerability is eliminated, but the system complexity increases

Engineering Contradiction:

Improveplaintext exposure riskVSAvoidtransform application and inversion

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The reversible transform modifies the media data by applying parameter changes to the plaintext before compression. These changes are designed to be computationally efficient while providing strong protection. The transform uses key material to modify data parameters such that the transformed output appears unrelated to the original plaintext, yet can be efficiently reversed with the appropriate key during authorized playback.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9922173B2Digital rights management

Publication Date: 2018.03.20 CLAYDO LAB

AI summary

A method of DRM protection for an image or a series of images or a succession of video frames, comprises: generating a reversible transform; applying the reversible transform to a source image; compressing the transformed image into a bitstream; and supplying the bitstream to a recipient for consumption. At the recipient the bitstream is decompressed and sent to the image display hardware with the transform still in place. A key is used to generate the inverse transform at the recipient and the inverse transform is then carried out in the image display hardware. An additional transform may be applied to the image following the inverse transform to offset pixels from an average value. Thus the source image itself is never exposed at the recipient although the image can be correctly viewed.