Signs that can reveal a fake photo (2017)

I used to think that the internet would be the greatest tool for human peace ever invented. But I was wrong. I didn’t know that humans don’t use reason to determine their position. The use it to justify their position and Google provides the greatest tool ever built for allowing people to do exactly that.

All the mainstream reputable news organizations use stock photography extensively, so the public is generally willing to accept that the photograph attached to the headline needn't have anything to do with that headline.

Personally, I think this practice should be ended or at least decreased greatly. An article about a ship doesn't a stock photograph of a ship. It probably doesn't even need a photograph about the particular ship the article is discussing, unless there is something visually unusual or notable about that ship. The formula "Ship A is late to port, here is a stock photo of Ship B" is basically worthless. I guess they're tossing a bone to the borderline illiterate who are stuck at the "I can read picture books" level of literacy? But generally articles themselves are written at a higher 'reading level' than that.

Snopes often refers to these as "miscaptioned."

Rolling Stone didn't even produce a proper retraction (calling it an update) for their fake news piece from that picture caption on horse dewormer and hospitals being allegedly overwhelmed.

https://twitter.com/ggreenwald/status/1434854957614780424

In this scenario, it would almost certainly have to be that manufacturers would have to build cameras that cryptographically sign the images and videos. The cameras would have to be able to have that ability, install of the manufacturers doing the signing.

And then what would the Blockchain provide in this case? A chain of cryptographically signed certificates back to a manufacturer is basically the same system we use on the web today TLS certs. No Blockchain required.

And a major problem with that system is making sure the camera only signs genuine images. A nation state actor, or even a large political operation, is going to have an incentive to bypass the protections on that camera - perhaps just driving what the CCD is telling the rest of the camera - so they can produce signed fakes.

That's if they can't just get the private key off the camera, perhaps through a side channel attack - which can be pretty tough to pull off but is very tough to really defend against. Get a private key, game is over for the fraudster.

This might lead into a direction we don't want to go. E.g. camera manufacturers can add DRM so you can't copy photos and movies, fingerprinting for CSAM, etc.

Just give me the raw image sensor.

Wouldn't filming a good quality screen with a higher refresh rate than the camera FPS defeat this method entirely? Especially so if the desired result is not itself high-def.

Exactly. In fact, that's the approach[0] taken by my new startup.

[0] https://www.tovera.com/tech

No. "Trusted" hardware merely creates the illusion of a secure system, while allowing those with the resources to defeat it anyway. First, there would be 20 years of bugs after having to root your camera became a thing. Two, unless the sensor modules themselves are made into trusted components, it would be relatively easy to wire up a mock sensor to the "secure" processor. And three, camera makers would eventually be pressured to undermine the system's security invariants, ala Apple.

I was speaking with someone from the military. It seems that's more or less required in some cases for interrogations, taking pictures of proofs, etc. With time-stamping and GPS coordinates using purpose-built cameras.

I can easily imagine the camera digitally signing pictures and asking for notarization. But there will always be an analog hole -- and the first faked pictures weren't altered after shooting, the scene was.

I'm all for fakes being widespread. It makes people more critical of what they see, and protects them against the few that had this capability before.

It is solvable by punishing anyone who posts fake pictures. Since the problem of bad actors in society has existed for millennia, we anyway know a dozen ways to deal with it. We just haven’t really bothered to apply any of them to the Internet.

Why we haven’t done that is a different but equally fascinating question.

Assuming that media and consumers will want to consider photos/videos of random everyday people, it would require that:

1. All manufacturers, including manufacturers of shoddy but cheap mass-market devices (ones that a not-wealthy person would have on them to document interesting events) support that cryptographic signing in all their devices;

2. None of the signing keys/secrets can be ever extracted from any such devices;

3. None of these manufacturers or their employees ever generate a valid key (or a million valid keys) that would have been put in a camera of the same model that respected journalists use, but are just available to the government where the factory resides, or just for sale on some internet forum to sign whatever misinformation a resourceful agent wants to publish.

Signing pictures can mostly work with respect to a limited set of secure, trusted hardware manufactured and delivered with a trusted chain of supply, where a single organization is in charge of the keys used and the set of keys is small enough to control properly. E.g. Reuters might use it to certify photos taken by Reuters people using specific Reuters-controlled camera hardware (and they can do that just by ordinary signing of what they publish). But there's no motivation for most people in the world to accept that overhead for the devices they use for photography and video, and there's no single authority to control the keys that everybody else would trust due to international relations.

It's an interesting rat race to see; you could make a fake image using AI, then a fake image detector software, then connect the two until the AI generates images no longer recognizable as fake.

But cameras aren't perfect pinholes though. The center of the sensor and the optical axis of the lens are already not perfectly aligned, and the sensor is not necessarily perpendicular to the lens barrel. These distortions might be larger than any change of size due to an object being in the periphery of the field of view, especially for longer focal length where the rays are more parallel.

Block chain can at best give you chain-of-custody, but it can't help with the real problem - the original source. Trusting the original source requires, well, trust, so a block chain really adds very little to the solution.

But this only works if all views of the images employ your client... If I download an image (screenshot if necessary), modify it, and host it myself, how does the system work then?

And, unless all users trust only things viewed securely, and distrust things viewed nonsecurely (out of your client), then misinformation and fake photos can still propagate, right? (Or, how does the system handle this?)

Interesting idea, but it's not obvious to me in what way you would apply it.

For example, compositing two images that somehow obey Benford's law should result in something that also obeys it.

Maybe you mean "Benford's law" as in "just general stastical properties", but I hope you had something more specific in mind.

Nice catch. The article was republished. Here's an archive from 2019 of the original 2017 version:

https://web.archive.org/web/20191030232152/https://www.bbc.c...

We've added the year to the title now. Thanks!