Soft Redaction of Image Provenance via Zero-Knowledge Proofs
Summary
This paper introduces a novel approach to soft redaction of image provenance using zero-knowledge proofs (ZKPs), enabling privacy-preserving claims about sensitive metadata while maintaining the integrity of C2PA standards. The work explores three use cases: location proximity, biometric likeness, and perceptual hashes, demonstrating practical implementations with efficient proof generation and verification.
Mathematical/empirical assessment
The paper presents a well-structured mathematical framework for ZKP-based soft redaction, particularly focusing on ell2 distance proofs. For location assertions, it uses Chebyshev polynomial approximations to handle trigonometric functions within the ZKP circuit, achieving acceptable accuracy with degree-5 polynomials. The empirical results in Table 1 show that these approximations are effective across various geographic scales. The ell2 distance circuit is implemented efficiently using PLONK, with manageable constraint counts and sub-second verification times. The evaluation on LFW and MIRFLICKR-25k datasets confirms the feasibility of the approach for biometric and fingerprint-based applications.
Strengths
The paper makes a timely contribution by addressing the tension between provenance transparency and privacy in digital media. It provides concrete examples of how ZKPs can be applied to C2PA, offering a practical solution for soft redaction without compromising the trustworthiness of the provenance record. The implementation details, including circuit design and performance metrics, are thorough and well-documented. The use of PLONK for ZKP construction is a strong choice, given its balance of efficiency and flexibility.
Concerns
While the paper demonstrates promising results, it would benefit from a more detailed discussion of potential limitations, such as the computational cost of proof generation for high-dimensional embeddings. Additionally, the paper does not explore alternative ZKP systems like Groth16 or Bulletproofs in depth, despite their relevance to different use cases. A comparison of trade-offs between these systems could strengthen the analysis.
Final decision
Weak accept