Anti-collusion Watermark Payload Shuffling via Pseudo-random Permutation
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Solution Overview
Problem
Existing anti-collusion watermarking solutions, such as Tardos codes, require long payloads that are impractical for sequence key-like watermarking strategies, as they necessitate hundreds or thousands of bits, which is not feasible for all digital watermarking approaches.
Innovation Solution
The proposed solution involves shuffling the watermark payload and embedding it in content using a pseudo-random permutation generator, where the payload includes a model number and individual device identifier, allowing identification of colluding principals by invariant model numbers and permutating bit positions within the payload to maintain security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Tardos codes are used for anti-collusion watermarking, then collusion detection capability is improved, but payload length becomes excessively long (hundreds or thousands of bits)
Solution Approach 1:
The patent segments the payload into two distinct parts: a model number field and an individual device identifier field. This segmentation allows the system to use a short payload (avoiding the hundreds-of-bits requirement of Tardos codes) while maintaining anti-collusion capability through the combination of shared model numbers among colluders and unique individual identifiers.
Solution Approach 2:
The patent applies local quality by making different parts of the payload serve different functions: the model number field provides group identification for collusion detection, while the individual device identifier field provides unique device fingerprinting. This localized functional differentiation enables effective anti-collusion with minimal payload length.
2Reliability
If payload positions are permutated for security, then anti-collusion robustness is improved, but payload embedding complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining a permutation mapping between the original payload bit positions and the shuffled positions. This permutation table is generated in advance and stored, allowing the embedding system to simply look up and place bits according to the pre-computed mapping, rather than performing complex real-time permutations during embedding.
Solution Approach 2:
The patent introduces a permutation mapping table as an intermediary between the original payload and the embedded payload. This intermediary structure simplifies the embedding process by providing a straightforward lookup mechanism, reducing the computational complexity while maintaining the security benefits of position shuffling.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
Embedding a watermark payload in content, including: a counter configured to store a random seed; a permutation generator configured to receive and process the watermark payload and the random seed, and generate a shuffled payload based on the random seed; and a watermark embedder configured to receive and embed the shuffled payload into the content. Key words include watermark payload and collusion.