Comment by ranger_danger
16 hours ago
There will always be a way around it. There are even open-source alternative/hacked firmwares for professional DSLR cameras where tampering with the signing may be possible.
And this still doesn't help any other kind of image e.g. screenshots, photo of a screen etc. that can make the camera signatures largely pointless depending on the context.
The idea is to be able to prove that a photo you took was captured by a camera, not generated. That would be helpful in the context of a disputed news story, a court case, etc.
Would that ever be relevant for a screenshot?
It's not massively helpful for a court case, IMO. This has been handled the same way since the invention of photography: ask the photographer to swear under oath they took the photo. (technically, laying a foundation for the evidence)
Yes in multiple ways, and there's probably more than this:
It's relevant that a screenshot doesn't have a signature, in the case that you want to remove any "proof" or tracking info from a real photo when uploading an image. Maybe I don't want people to know what brand/model of camera I use.
And it's relevant if a screenshot did have a signature if you want to "prove" that the screenshot itself hasn't been tampered with after the fact.
In the method proposed in the paper, the signature is stored in the pixels and ostensibly even survives some compression. So if you made a screenshot of a signed image, the image would still have its signature inside the screenshot, but the screenshot wouldn't have any (new) signature as a whole.
That's how I understood it at least.
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