Paper 2024/1066

VerITAS: Verifying Image Transformations at Scale

Trisha Datta, Stanford University
Binyi Chen, Stanford University
Dan Boneh, Stanford University
Abstract

Verifying image provenance has become an important topic, especially in the realm of news media. To address this issue, the Coalition for Content Provenance and Authenticity (C2PA) developed a standard to verify image provenance that relies on digital signatures produced by cameras. However, photos are usually edited before being published, and a signature on an original photo cannot be verified given only the published edited image. In this work, we describe VerITAS, a system that uses zero-knowledge proofs (zk-SNARKs) to prove that only certain edits have been applied to a signed photo. While past work has created image editing proofs for photos, VerITAS is the first to do so for realistically large images (30 megapixels). Our key innovation enabling this leap is the design of a new proof system that enables proving knowledge of a valid signature on a large amount of witness data. We run experiments on realistically large images that are more than an order of magnitude larger than those tested in prior work. In the case of a computationally weak signer, such as a camera, we are able to generate proofs of valid edits for a 90 MB image in under an hour, costing about \$2.42 on AWS per image. In the case of a more powerful signer, we are able to generate proofs of valid edits for 90 MB images in under five minutes, costing about \$0.09 on AWS per image. Either way, proof verification time is about 2 seconds in the browser. Our techniques apply broadly whenever there is a need to prove that an efficient transformation was applied correctly to a large amount of signed private data.

Metadata
Available format(s)
PDF
Category
Applications
Publication info
Preprint.
Keywords
image provenanceC2PAzero knowledge
Contact author(s)
tcdatta @ stanford edu
binyi @ cs stanford edu
dabo @ cs stanford edu
History
2024-07-02: approved
2024-07-01: received
See all versions
Short URL
https://ia.cr/2024/1066
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/1066,
      author = {Trisha Datta and Binyi Chen and Dan Boneh},
      title = {{VerITAS}: Verifying Image Transformations at Scale},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/1066},
      year = {2024},
      url = {https://eprint.iacr.org/2024/1066}
}
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