I think it's useful even if it can be spoofed. Many people don't even bother to edit visible watermarks out of AI photos/videos. I'm fairly certain this will defeat 99.9% of malicious users, many of whom won't even know it exists until someone points out it's missing.

People are concerned that the technology will lend additional credence to the last 0.1%. But anyone who thinks about the technology for 2 minutes will see you can just point the camera at the screen. In cases where it really matters (a court of law, internet arguments between nerds) people will know it's not 100% reliable. Locks can be picked, and signatures can be forged, but that doesn't make them useless.

"C2PA Cameras Do Not Survive Contact With Reality" does not survive contact with reality where very, very few users would even think of rooting their phone so they can create signed fake images.

In my opinion, the benefits for end users are rather minimal since I doubt an average person would ever be checking C2PA provenance data, but there is a commercial incentive for Google and others to promote C2PA, since it makes preparing training material for Machine Learning significantly easier, and perhaps as a smaller benefit justifies hardware attestation that locks users down into proprietary OSes.

I don’t think there is a technical solution to this problem but I think there is a legal one.

Make it a legal requirement to mark AI generated photos and enforce penalties for posting unmarked AI generations. Social media should also mark the country of origin for each post, with the knowledge that posts from your own country are covered by these laws.

Are we entering a world where if I took a picture with a film camera and scanned it, it would be rejected as not real?

This is ridiculous.

C2PA is a bit nebulous as a concept, which is part of the problem. It is both of these things. The BBC type use case where a publisher signs their own content with their own keys seems reasonable to me, or at least, not obviously broken.

However I question the value-add when e.g. the BBC website is already authenticated by nature of being served over HTTPS, and anyone who redistributes BBC content can and should link back to the source.

> It's always been obvious that one could point a camera at a screen, I don't think anyone involved with C2PA has claimed otherwise.

They haven't claimed otherwise exactly, but some have implied it's a solvable problem. Here's where the "learn more" link goes, for when Youtube annotates a video as having C2PA metadata: https://support.google.com/youtube/answer/15446725 (Google is a C2PA Steering Committee member)

> The metadata that leads to a 'Captured with a camera' disclosure is made by a third party (for example, a camera manufacturer). This means that there is some risk that someone could take a photo of another screen showing synthetic content. Because the other screen shows an image that has been modified, it wouldn't be eligible for the 'Captured with a camera' disclosure. This issue is called 'air-gapping'. Camera manufacturers will continue to develop detection measures to prevent 'air-gapping', but the sophistication of those detection measures may vary in the near term.

Interestingly they do not mention any of the other known limitations. Their phrasing is highly weasel-wordy, but the implication is clearly that they imagine picture-of-screen detection to become robust (somehow) in the medium-to-long term.

Why not just have BBC sign stuff with their own creds then? You can originate the chain of custody anywhere and relying on the camera is kind of silly when the reputation of the original publisher in a more meaningful backstop.

Actually I think this approach is very forward looking! Attestation is on the cusp of becoming a very powerful technique. We just need to figure out how to build 100% bug-free and 100% secure hardware and software, and then it's gonna work great.

Well, all one has to do is look at the bigger picture of how rooted devices are being shuffled into 3rd rate/totally blocked experiences and the overall direction of things starts to take very clear shape.

At over a decade old, still prescient as ever: https://www.youtube.com/watch?v=HUEvRyemKSg

Not any rooted device, it must be rooted via an exploit. Still pretty bad, though

And I'm not sure it's even useful to solve. The presence/absence of a digital signature will never be the deciding factor in whether people accept/reject an image as authentic.

And in 2026, I don't think it's too big of a stretch to imagine that there are going to be people in power that can add + remove the metadata to whatever image they want, at will, to tell whatever story they want to create. Sadly.

> Even then, you could attack it from the next level up, with some fancy optics and a display, or something like that.

The analog hole is alive and well:)

Until it matters. Which you are proposing happening.

As far as AI-generated images go, that was a good one.

That might be detectable if they signed content contains focal-length metadata... but even then, some foresight and a collection of lenses would hide it.

Wouldn’t the introduction of the lidar signals embedded in the photo (say used with apple’s faceid system) help here?

see also https://en.wikipedia.org/wiki/Telecine

Transferring electronic images to film is a long-solved problem.

https://en.wikipedia.org/wiki/Film_recorder

You can expose a negative with whatever the fuck you want. It doesn't have to be a real scene.

Does that prove you didn't photograph a display showing the digital image?

My bet is they do considerably worse. Digital cameras are not designed with security in mind. Arbitrary code execution has been achieved on many DSLRs and there's even been open-source firmware projects for some.

Unfortunately they're a little outside of my tinkering budget, but if anyone wants to send me some I'll do my best to pwn them. Can't be any harder than a Google flagship, one would imagine.

I have ordered a faulty Sony A7 IV motherboard, but due to its faulty-ness and the lack of the rest of the camera, I'm not sure how far I'll be able to get with it.

Why would someone paying for an expensive camera to damage the pixels of their images with "invisible" watermarks?

Apple isn’t going to touch this with a 10-foot pole.

The provenance “proof” these approaches provide is very tenuous and nowhere near the “this is a real photo of a real world event taken by a real camera and not an AI image” proof that marketing types like to push.

Apple doesn’t want a PR disaster where some crazy image is totally fake but becomes world news because it is “cryptographically signed as being from a real iPhone so it must be real!”