[hdm41bc]

Is this a solvable problem by requiring camera manufacturers cryptographically sign photos and videos created on those devices? If that’s in place then it seems like it could be the basis for chain of custody of journalistic images backed by a blockchain. This seems like the only viable solution to me since any AI powered solution would just be a cat and mouse game.

[kc0bfv]

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.

[hdm41bc]

The way I thought that the blockchain would be employed is to use it to track transformations of the image. Post-processing, adding captions, and what not. This would provide an audit trail of changes to the original source image.

If, in fact, we can’t reliably sign the source image as authentic, then the rest of the system falls apart. It seems like this is the crux of the problem.

[someguyorother]

That seems to be a DRM problem. Let's say that you want the camera to track all modifications of the picture. Then, analogous to DRM, there's nothing stopping the forger from just replacing the CCD array on the camera with a wire connected to a computer running GIMP.

To patch the "digital hole", it would be necessary to make the camera tamperproof, or force GIMP to run under a trusted enclave that won't do transformations without a live internet connection, or create an untamperable watermark system to place the transform metadata in the picture itself.

These are all attempted solutions to the DRM problem. And since DRM doesn't work, nor would this, I don't think.

[chasil]

If a signed sha256 is somehow attached in the exif data, it can be removed.

What digital rights are there to manage? This would be a statement of authenticity, not proliferation control.

The vendor's private key would have to be stored in the device. How could it be protected from extraction?

[grumbel]

> And then what would the Blockchain provide in this case?

The main thing a blockchain provides is a cryptographically secured logbook of history. It doesn't guarantee you that the entries in the logbook are true, but it gets a lot harder to fake history when you can't go back to change your story. You have to fake it right when you claim it happened and hope that nobody else records anything in the logbook that conflicts with your story.

[kc0bfv]

I can see how then a journalist source could use this to help prove their integrity. And I like that as a solution for that...

But - I don't really see that as the issue today. Those outlets that are interested in lying don't have to participate in this Blockchain chain of proof system. The malicious entities like political groups cited in the article definitely don't have to participate. It's still really on the viewer/spreader of the fake images/misinformation to verify the images, and to only rely on verifiable images. But I think a system like that would leave out most of the population who simply don't care.

Perhaps my worry about leaving out that chunk of population means this problem is unsolvable - and therefore my point is unfair. But I do think we need some solutions that are practical for widespread acceptance and use. If I can't imagine my parents (who are tech literate) would participate, and can't imagine some of my non-nerd friends wanting to participate, I don't think it solves the problems I'd like systems like this to solve.

[hdm41bc]

I don’t think most people need to adopt this on their cameras for it to work. My perspective here is that journalistic sources that want to be trusted could employ this system. Along with signing the media and the blockchain, a system would need to be built to simply show the change log and history of a photo from the source. These journalism websites could just link out to it to demonstrate their veracity.

Once that’s adopted by the NYTs, WSJs, BBCs of the world, I’m hoping there would be critical mass to pressure more and more journalistic sources to adopt this standard. Eventually, any credible journalism would be on this technology and any outlet that doesn’t use this would be viewed with a grain of salt.

I agree though that a number of developments would have to happen to make this a reality. I would think that a partnership between NYT and Apple or Nikon could kickstart it though.

[kkielhofner]

The problem with using certificates is any media signed by a party (by nature) traces directly back to that source/certificate. With a certificate-based approach I can imagine something like Shodan meets Google Image Search being used to make it easier to source media for the purposes of enhancing training for an ML model. Needless to say I have serious concerns about this approach.

This is why our approach only embeds a random unique identifier in the asset and requires a client to extract the media identifier to verify integrity, provenance, etc.

There are also two problems at play here - are we trying to verify this media as being as close to the source photons as possible, or are we trying to verify this is what the creator intended to be attributable to them and released for consumption? The reality is everyone from Kim Kardashian to the Associated Press performs some kind of post-sensor procession (anything from cropping, white balance, etc to HEAVY facetunning, who knows what).

[kc0bfv]

Ok - I like this for some use cases. To restate my understanding so you can tell me I'm wrong if I am:

I think that it's still the user's job to make sure that they are skeptical of the provenance of any photos that claim to be from, say, the NY Times, that are not viewed in the NYT's viewer (if they were using your system). And then, they should still trust the image only as far as they trust the NYT. But if they're viewing the image the "right" way they can generally believe it's what the NYT intended to put out.

And perhaps, over time, user behavior would adapt to fit that method of media usage, and it would be commonplace.

I am skeptical that that "over time" will come to pass. And I think that users will not be apply appropriate skepticism or verification to images that fit their presuppositions. And I think malicious players (like some mentioned in the article) will attempt to build and propagate user behavior that goes around this system (sharing media on platforms that don't use the client, for instance).

And I guess making that broad set of problems harder or impossible is really what I'd like to solve. I can see how your startup makes good behavior possible, and I guess that's a good first step and good business case.

[kkielhofner]

It's probably best for me to provide an example. We create three URLs for each media asset. For [1], [2], and [3] you can click our icon in the top right corner:

- A link to the asset itself (just the JPEG or whatever with embedded ID) [0]

- A link to a preview with twitter card, facebook open graph, etc support suitable for sharing (and re-sharing) on social media [1]

- A link to an iframe embed for use wherever else [2]

For an asset where the user has configured the metadata to be hidden our verification API doesn't return anything other than the checksum to validate against [3].

Users can update the returned metadata at any time or hiding of the extended metadata and it's updated dynamically and instantly - everywhere. So this way producers and consumers of content don't need to have a dedicated consumption implementation (but it could certainly be branded or white labeled to the content producer). Currently the client is just our javascript but we're working on mobile and browser extensions that can run anywhere against the raw asset link provided in [0].

[0] https://share.tovera.com/assets/c65b0658ab6e4d89963b1e0a319a...

[1] https://share.tovera.com/preview/c65b0658ab6e4d89963b1e0a319...

[2] https://share.tovera.com/embed/c65b0658ab6e4d89963b1e0a319a1...

[3] https://share.tovera.com/preview/e51de3d34bfe47d7bc25fb8f252...

[amelius]

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.

[antifa]

I can totally see someone trying to set this up, then instead of any of the benefits actually working as advertised, photography costs $80 in etherium per photo.

[PeterisP]

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.

[MayeulC]

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.

[mindslight]

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.

[tsimionescu]

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.

[wussboy]

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.

[kkielhofner]

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

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