Even if you didn't know who owned the camera, you could identify other pictures taken by that same camera, and information in those photos might let you figure out who owns the camera.
If authenticity later becomes an issue you can produce the original.
You could use this data to prove that image B is an edit of image A if you already have both A and B.
I still think this is a bad idea, because this all requires the images to have some sort of ID - and that seems like a prime target for tracking.
Nobody cares if your social media photos are edited, they probably are, it's fine.
This has been the case for many years, and so far social media sites never care - they strip that info instead. Why would this change with one more extra piece of metadata?
Can you clarify what your actual complaint is here? Putting aside for a second obvious implementation options, it's pretty standard that there can be a tradeoff between privacy and trust. Any of us are still perfectly free to upload images for fun to forums or social media or whatever that are private, or edited or whatever we like. But if there's something we [i]want[/i] to prove, this gives an extra option to do so. And in particular the set of cases where one cares the most about enhancing authenticity appears at first thought to be pretty much a union set with the cases where one will put their name (or at least the location and time of the picture in question) behind the image? Like, can you give examples of specific cases you are imagining where simultaneously the photo itself reveals no information about time and location [i]and[/i] it's something local/national/international-newsworthy where people would fear AI-alteration? Like, say you're photographing at a protest to document it including any violations of law. By definition, the images you take reveal the location and the time. That's the whole point of them. Having the location and timestamp signed wouldn't reveal anything extra as long as the photo was unaltered.
And actual legit journalism always has name(s) standing behind the reporting. Or for that matter, even if we're merely talking something like a review of a product, is it actually wrong to put a name or pseudonym behind that review if you expect readers to give you much credence? I mean, you'd be free in terms of law and tech to not bother. But even long before the current growing AI-slop age a lot of us have been starting to treat anonymous reviews with a lot of skepticism, or discounting them entirely for some product classes, for good reason.
Even in terms of maintaining privacy, remember we already have "tools" for that which this in turn could further help. You could privately report a tip to a reporter at a media organization, and then they could report on that without revealing you but be able to say "we verified the signature of the raw image and sensor data" alongside normal follow up. Then it's their name, but having a stronger chain behind it could still be helpful in places.
Finally getting back to "implementation options", there's no technical reason the image and multiple sets of metadata can't all be signed separately by the sensor stack such that you can pick & choose what to include and still have it all be signed, with readers giving greater or lesser weight to the trust based on your choices.
> Any of us are still perfectly free to upload images for fun to forums or social media or whatever that are private, or edited or whatever we like.
First, the paper proposed a method of embedding the metadata inside the actual image pixels in a way that makes it difficult to remove. I think it's still possible, but you're will need a specialized tool to do so and it will alter the image.
Second, that's assuming forums or social media would still be allowing uploading unsigned images. If AI images really become as much of a problem as anticipated here, then sites might decide to block any image they can't verify completely.
> Like, can you give examples of specific cases you are imagining where simultaneously the photo itself reveals no information about time and location [i]and[/i] it's something local/national/international-newsworthy where people would fear AI-alteration?
All kinds of photos from warzones have this property. We wouldn't have an entire science of geolocating photos from landmarks that were accidentally captured if everyone was so easy with putting their GPS coordinates in the file.
is a post about Google Pixel C2PA cameras experiencing contact with reality
I'll write more about this in the future.
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.
Would that ever be relevant for a screenshot?
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.
That's how I understood it at least.