Forensic Steganography Watermarking Collusion Attack Prevention

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Solution Overview

Problem

Forensic steganography watermarking systems are vulnerable to collusion attacks, where an attacker can degrade the watermark by identifying and modifying different content segments across multiple sessions, making precise identification of a session impossible.

Innovation Solution

Introducing small modifications to unmarked frames, such as encoding macroblocks differently and varying quantization coefficients, to make every frame appear computationally different, preventing the attacker from determining which frames are marked or unmarked, thereby preventing collusion attacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If content segments are watermarked using A/B variants, then identification precision is improved, but vulnerability to collusion attacks increases

Engineering Contradiction:

Improveidentification precisionVSAvoidcollusion attack vulnerability

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by modifying encoding parameters (such as macroblock encoding mode, quantization coefficients, motion vector precision) for unmarked frames across different variants. This ensures that even unmarked frames have computational differences between variants, preventing attackers from identifying which frames are marked and thus preventing collusion attacks while maintaining identification precision through the watermarked frames

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements preliminary action by pre-modifying unmarked frames during the encoding process before distribution. By introducing computational differences in encoding parameters for unmarked frames in advance, the system prevents attackers from later identifying marked frames through comparison, thus proactively defending against collusion attacks

Inventive Principle:

Principle #10Preliminary action

2Reliability

If modifications are made to unmarked frames, then collusion attack prevention is improved, but device complexity increases

Engineering Contradiction:

Improvecollusion attack preventionVSAvoidencoding complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by making modifications only to specific portions of the content (unmarked frames) rather than the entire content. By selectively modifying encoding parameters for only the unmarked frames while leaving marked frames unchanged, the system achieves collusion attack prevention with minimal additional complexity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements partial action by modifying only the necessary encoding parameters for unmarked frames rather than re-encoding the entire content. This partial modification approach achieves the security goal while keeping the additional complexity manageable

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20240362739A1Collusion attack prevention

Publication Date: 2024.10.31 COMCAST CABLE COMM LLC

AI summary

Systems and methods are described for obfuscating variants of content segments. Variants of content segments can be used to encode an identifying sequence in a transmission of content. The variants of the content segments can each include one or more marked frames and one or more unmarked frames. Variations can be introduced into the unmarked frames for each of the variants of the content segments.