Aside from the fact that this was obviously never viable and the entire problem is clearly unsolvable if you sit down and really probe it for fifteen minutes, what I find most frustrating about this is that the false promise of preserving photos as reliable evidence is actively harmful.
You will not build a perfect system, or even something near perfect. The best you're going to do is make it so that it's hard to casually present AI photos as real, leaving only the cases where it really matters. In the "best" case, you've just made the public more trusting of photos in general, so that when there's actual money or power on the line that makes jumping through the hoops to fake authenticity worth it, the public is more susceptible.
The best outcome at this point is for everyone to get on the same page that photos have roughly the same probative value now as drawings. Poorly thought out snake oil efforts to prove authenticity are only going to delay that.
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.
When I search for "C2PA" on the google play store, there are more AI-watermark-removal apps than there are signing apps. Certain types will jump through ridiculous hoops if they think it will affect their algorithmic reach on social media.
Malicious users don't need to root their own phones. They just need to go to fakemyimage dot com, and someone else's rooted phone in a clickfarm-type setup signs it for them. I am not operating such a service myself because I thought it was unnecessary in making my point, but perhaps I will have to reconsider.
It's actually worse if it is plausibly trustworthy for "99.9%", since that's enough that naive users will get accustomed to believing the verification badge is authentic.
When a motivated malicious user (who doesn't actually need that much resources) will be able to convince people something is authentic because the verification passes when it shouldn't since naive users are primed to believe it by default.
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.
It's compliance for advertising. Your client doesn't want AI in their project you show them the audit trail and if it turns out to be faked you point to the supplier who faked it. Our agency signed a insurance not only because of clients who don't want to use AI in their artwork but also because of the EU AI act. They c2pa to get their money back from a cheating supplier if they are not compliant with the AI act.
I always got the impression that C2PA is a way to say "this photo came from the BBC (for example) and they've only signed it because they've verified the supplied edit chain". 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.
It seems like there's a big disconnect between what C2PA says it's for and what certain journalists think it's for.
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.
I'm very surprised Google put in so much effort to implement an approach that is basically the equivalent of client-side verification of passwords. Did no one designing it mention that it could be defeated by any rooted device?
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.
Even at the hardware level, if it was a separate chip that the camera data passed through or something, that's not really good enough either, people have broken TPMs before. It'd have to be baked into the camera sensor. Even then, you could attack it from the next level up, with some fancy optics and a display, or something like that.
I don't think completely solving this sort of problem is even possible.
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.
What I'm getting at is that metadata that claims that a photo is "real" won't necessarily convince people that it is, and the lack of that metadata doesn't mean anything at all. About the only real use I've seen for C2PA is to confirm that an image bearing that metadata is AI-generated - and that marker is easily lost through editing or retransmission.
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.
There were similar fears about the webtrust CA system, but AFAIK there's no known incidents where a government strongarmed a CA into misissuing a MITM certificate, and then it was used in MITM attacks. The closest is some misissued certificates seemingly due to incompetence but weren't used in attacks.
And at that level, it’s a matter of definition anyway. What is “AI generated”? A photo of a screen showing an AI picture is still a photo. If that’s “AI” then what about a photo of an AI generated billboard? Or a photo of a bus with an AI graphic on the side?
For the time being, I wish more workflows revolved around RAWs. You can pretty much prove the origins of an image sans cryptography by just possessing the image sensor data that you used to produce the final. It's not foolproof but AI image models can't really generate a convincing bayer raw and it's not something anyone is going to spend significant time training.
Isn't film photography verifiable with a physical negative? i.e. you could verify a digital reproduction of the analog photo by comparing the digital image with the negative. Tedious, but sound?
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.
I would be interested in a note on whether Sony / Leica / Olympus “content credentials” do any better with their hardware to ensure a signature is assigned to data straight off the sensor.
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.
I have a feeling Apple is going to knock it out of the park on this when they get around to it. They have a great foundation for doing image provenance well. The device attestation workflows are already there. And the same attacks that work against Android won't be as easy or effective because of Secure Enclave. Apple could run the whole signing process inside SEP.
And, Apple could choose to integrate a LiDAR depth map into the signed photo as a mitigation against the analog attacks (eg. pictures of screens).
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!”
>Images captured with an opt-in Reference mode can be authenticated to confirm they were taken with an iPhone. Authenticating is done by tapping the Reference badge on the image, which sends the raw image, sensor signatures, capture time frame, and the unique hardware identifiers of the sensor to Apple's Private Cloud Compute (PCC) servers. PCC uses the information to determine whether the camera captured the photo, gives it a unique ID, and then returns an authenticated version to the user's device.
I expect the only plausible chance (and it is a stretch) will be at-the-censor marking. Quantum bla bla magic pixie dust or unicorn farts something. The chance of a trustworthy (including from nation-state tampering a la Stalin et al) means of verification of digital anything is as good as dead imho.
Aside from the fact that this was obviously never viable and the entire problem is clearly unsolvable if you sit down and really probe it for fifteen minutes, what I find most frustrating about this is that the false promise of preserving photos as reliable evidence is actively harmful.
You will not build a perfect system, or even something near perfect. The best you're going to do is make it so that it's hard to casually present AI photos as real, leaving only the cases where it really matters. In the "best" case, you've just made the public more trusting of photos in general, so that when there's actual money or power on the line that makes jumping through the hoops to fake authenticity worth it, the public is more susceptible.
The best outcome at this point is for everyone to get on the same page that photos have roughly the same probative value now as drawings. Poorly thought out snake oil efforts to prove authenticity are only going to delay that.
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.
When I search for "C2PA" on the google play store, there are more AI-watermark-removal apps than there are signing apps. Certain types will jump through ridiculous hoops if they think it will affect their algorithmic reach on social media.
Malicious users don't need to root their own phones. They just need to go to fakemyimage dot com, and someone else's rooted phone in a clickfarm-type setup signs it for them. I am not operating such a service myself because I thought it was unnecessary in making my point, but perhaps I will have to reconsider.
It's actually worse if it is plausibly trustworthy for "99.9%", since that's enough that naive users will get accustomed to believing the verification badge is authentic.
When a motivated malicious user (who doesn't actually need that much resources) will be able to convince people something is authentic because the verification passes when it shouldn't since naive users are primed to believe it by default.
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.
The EU did this, Claude and Microsoft complied and HN was practically rioting about it literally yesterday: https://news.ycombinator.com/item?id=49421158
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.
It's not a matter of "rejected as not real", it's "There's no way to know if this is real or not".
The defendant submitted a remarkably high quality video of you saying you generated it with Nano Banana.
And their video was C2PA signed.
It's compliance for advertising. Your client doesn't want AI in their project you show them the audit trail and if it turns out to be faked you point to the supplier who faked it. Our agency signed a insurance not only because of clients who don't want to use AI in their artwork but also because of the EU AI act. They c2pa to get their money back from a cheating supplier if they are not compliant with the AI act.
I always got the impression that C2PA is a way to say "this photo came from the BBC (for example) and they've only signed it because they've verified the supplied edit chain". 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.
It seems like there's a big disconnect between what C2PA says it's for and what certain journalists think it's for.
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.
I'm very surprised Google put in so much effort to implement an approach that is basically the equivalent of client-side verification of passwords. Did no one designing it mention that it could be defeated by any rooted device?
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.
Wait a minute. I think you might have forgotten a /s, I can spot this kinda thing.
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
Even at the hardware level, if it was a separate chip that the camera data passed through or something, that's not really good enough either, people have broken TPMs before. It'd have to be baked into the camera sensor. Even then, you could attack it from the next level up, with some fancy optics and a display, or something like that.
I don't think completely solving this sort of problem is even possible.
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.
Yeah this is what I don't get why are people even spending time on this.
Is this picture real or AI is a real problem it is worth money to solve.
What I'm getting at is that metadata that claims that a photo is "real" won't necessarily convince people that it is, and the lack of that metadata doesn't mean anything at all. About the only real use I've seen for C2PA is to confirm that an image bearing that metadata is AI-generated - and that marker is easily lost through editing or retransmission.
Why? An image should never be proof of anything, by itself.
A desperate attempt to preempt regulation.
A desperate attempt to establish their version of regulatory capture and not have to pay licensing fees to the other guy
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.
There were similar fears about the webtrust CA system, but AFAIK there's no known incidents where a government strongarmed a CA into misissuing a MITM certificate, and then it was used in MITM attacks. The closest is some misissued certificates seemingly due to incompetence but weren't used in attacks.
And there are unicorns living at the end of the rainbow.
> 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:)
And at that level, it’s a matter of definition anyway. What is “AI generated”? A photo of a screen showing an AI picture is still a photo. If that’s “AI” then what about a photo of an AI generated billboard? Or a photo of a bus with an AI graphic on the side?
For the time being, I wish more workflows revolved around RAWs. You can pretty much prove the origins of an image sans cryptography by just possessing the image sensor data that you used to produce the final. It's not foolproof but AI image models can't really generate a convincing bayer raw and it's not something anyone is going to spend significant time training.
Until it matters. Which you are proposing happening.
Isn't film photography verifiable with a physical negative? i.e. you could verify a digital reproduction of the analog photo by comparing the digital image with the negative. Tedious, but sound?
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?
I got a good laugh out of the "unblur to verify" first image. I dont know what I was expecting to see.
As far as AI-generated images go, that was a good one.
I can break it with zero skills. Tripod, camera, clear monitor in a dark room ... just take a real photo of a fake photo.
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
I would be interested in a note on whether Sony / Leica / Olympus “content credentials” do any better with their hardware to ensure a signature is assigned to data straight off the sensor.
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.
Could you make use of a Sony a6000?
Why would someone paying for an expensive camera to damage the pixels of their images with "invisible" watermarks?
The signature doesn't touch the image data in any way. It's just a piece of metadata attached to the image, like any other metadata tag.
Surely the easiest thing to target is photos taken by journalists and modifications, down sampling etc when shared to twitter?
I have a feeling Apple is going to knock it out of the park on this when they get around to it. They have a great foundation for doing image provenance well. The device attestation workflows are already there. And the same attacks that work against Android won't be as easy or effective because of Secure Enclave. Apple could run the whole signing process inside SEP.
And, Apple could choose to integrate a LiDAR depth map into the signed photo as a mitigation against the analog attacks (eg. pictures of screens).
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!”
Apple is working on their own system, which is expected to launch with IOS 27: https://www.macrumors.com/2026/08/10/ios-27-apple-reference-...
>Images captured with an opt-in Reference mode can be authenticated to confirm they were taken with an iPhone. Authenticating is done by tapping the Reference badge on the image, which sends the raw image, sensor signatures, capture time frame, and the unique hardware identifiers of the sensor to Apple's Private Cloud Compute (PCC) servers. PCC uses the information to determine whether the camera captured the photo, gives it a unique ID, and then returns an authenticated version to the user's device.
I expect the only plausible chance (and it is a stretch) will be at-the-censor marking. Quantum bla bla magic pixie dust or unicorn farts something. The chance of a trustworthy (including from nation-state tampering a la Stalin et al) means of verification of digital anything is as good as dead imho.