Comment by kmeisthax | Hacker News Reader

Comment by kmeisthax | Hacker News Reader

>Editors then work with the pictures, and each successive modification or edit creates a new record in a private database (ProvenDB) that is indexed to the original registration. This allows edit logs to be kept private, but these logs also have their authenticity records registered on the Hedera public ledger.

How exactly do you keep the edit log private without completely losing the chain of authenticity here? One of those edits might be to, say, double the size of a plume of smoke or change a signal flare into a set of missiles[0]. All you have is a promise that at some point, someone opened a real image in some kind of editing software.

The inclusion of a bunch of blockchain nonsense to store the verification also smacks of amateurism. You don't need a public chain with financial costs attached to secure photos you validate yourself. You can just publish a bunch of hashes and a hash of the prior block. Certificate Transparency does this and it works.

[0] https://en.wikipedia.org/wiki/Adnan_Hajj_photographs_controv...

Provided the signature of the original raw pixels is left in the final JPEG, I think Canon/Reuters can be expected to produce those original bits to any sufficiently curious/legally authorised third party, who can verify the signature to check that they are indeed the original bits. At that point said third party has the initial and final images, which is likely enough to conclude whether the edits were legit (the chain of edits themselves isn't as interesting).

Mostly agree on the blockchain shenanigans, though I suppose using an external blockchain allows you to prove that the image was taken before a certain point in time.

I don't see how this could work, unless they're using some sort of tamper proof perceptual hash (does such an algorithm exist?). If they change any of the pixels in their edits, it's not going to match the original signature. If they compress it to jpeg it'll have a different signature. And nobody's going to request the huge RAW files for every photo.

So this scheme can work to ensure that you're seeing the Reuters published version, not that Reuters itself didn't edit it after the camera took it.

I'm not talking about some software thing that automatically checks whether some image ("the edited image") is "similar enough" to some other image ("the original"). I'm claiming that their approach gives any interested person the ability to eyeball both versions and draw their own conclusions that way -- and that this is adequate for images intended for human consumption. (I didn't say the last part explicitly until now, mind you.)

Does that help?

Maybe my earlier reply misunderstood.

>nobody's going to request the huge RAW files for every photo

I don't see this as a big issue as there are several easy ways around it -- the simplest being that the camera could compute and store a second digital signature of a smaller, JPEG-compressed version at photo time. Another possibility is third-party businesses popping up that you (or even high-quality news agencies themselves) pay to do the human verification for you.

Usually there's not just one jpeg of a photo, but several. The camera might do one at a very high quality level, but that's going to be different than a downsampled one served over the web, or the mobile resolution one, or the color corrected one, etc.

Regarding your other comment, sure, such a manual system might be possible, but that relies on either Reuters publishing all of their unedited raw photos (which they probably won't) or a third party photo escrow service with all the rights to the Reuters originals. Neither seems likely.

I don't think this is an easy a problem as you might imagine? Perceptual hashing is a thing but there's no guarantee of forensic accuracy there.

Reuters has a history of doctoring its photos: https://en.wikipedia.org/wiki/Reuters (photo controversy section)

That last comment is a tad disingenuous - a photographer cloned extra smoke from attacks in a fairly obvious way that was quickly picked up, and another was a crop, fairly standard practice. Hardly a “history” of “doctoring” pictures.

I disagree. Those were substantial edits that exaggerated and biased the reporting. And those are just the ones we caught.

It's not OK when reporters or papers do things like that.

Direct link: https://en.wikipedia.org/wiki/Reuters#Photograph_controversi...

Perceptual hashing isn't relevant here in any way that I can see. That step just doesn't need to be automated in any way.

You have the final image (your browser downloaded it to display the page). Their new tech allows you to acquire something that you can be cryptographically certain is the original image. You can then look at the two images, and judge for yourself whether they look similar enough. Where does perceptual hashing come into it?

ETA:

>Regarding your other comment, sure, such a manual system might be possible, but that relies on either Reuters publishing all of their unedited raw photos (which they probably won't) or a third party photo escrow service with all the rights to the Reuters originals. Neither seems likely.

No it doesn't -- they just need to provide those photos on demand. (If they don't, then their system is a hoax -- like giving someone a key that doesn't open any lock.) See my other comments in this thread.

>Reuters has a history of doctoring its photos: https://en.wikipedia.org/wiki/Reuters (photo controversy section)

Didn't read the link but based on another's reply comment, the added smoke is exactly the type of fraud that this new system will detect the first time anyone bothers to check that photo.

Reply on news.ycombinator.com