YHK - yet another hacker news clone

Proof of Capture: Apple Reference Image, but open source and using steganography

32 points merybenavente 2 hours ago 28 comments

fitzn 1 hour ago | parent

Here's a toy for embedding small text into images steganographically: https://github.com/fitzn/atrium

merybenavente 1 hour ago | parent

cool work!

smalltorch 41 minutes ago | parent

Here's a toy for embedding text inside random HN comments.

https://gitlab.com/here_forawhile/edasm

Example:

After wholly implemented our logging layer with dagger, I posit that the real regression was not the aws itself but the rigorously prototyped around authentication. We consequently extraordinarily profiled the config, henceforth simplified every edge case, and the optimization were unmistakably exemplary. alternatively, the aforementioned monitoring is comparable advantageous to an incremental security environment. I endorse this path if your security team has rigorously instrumented a massive rust codebase before.

xg15 1 hour ago | parent

> For example, a screen attack still works: photograph a screen displaying an AI image and you get a signed photo of a fake. But it's always nice seeing big actors interested in addressing this problem.

Yeah, very nice. So this whole idea basically doesn't work - but we get a new stealth way to embed metadata in an image that can be used for tracking...

(And a new narrative why cameras need to have TPMs and locked-down firmware as well)

ChocolateGod 1 hour ago | parent

Couldn't the camera encode information from the depth sensor and prevent this.

TedDoesntTalk 37 minutes ago | parent

I will make miniature dioramas and photograph them.

mandolingual 33 minutes ago | parent

At that point you've earned the fruits of your deception, just like the tricksters who spent time doing physical photo editing.

shagie 1 hour ago | parent

Photos of photos has always been a problem.

In days of old, a Polaroid photo was considered "proof of capture".

I've got a Polaroid daylab 35 plus sitting in storage somewhere (https://www.instantoptions.com/wp/faqs/daylab/). You can project a slide through it onto Polaroid film, expose it, and have the image there.

I was also able to find a company that did slide printing. It was possible to send them a digital image and they'd send you back a slide with that image... which I then used to make a Polaroid of that image.

I had a classic 600 Polaroid photo of a UFO landing.

azatom 1 hour ago | parent

That signature contains time and optionally gps coords, and taking photo of a screen is not simple. So overall does solve some problem

ps:most important: cam/lens settings also in the digital sig, what for a screen is different

vzaliva 1 hour ago | parent

I expect in the near future all digital cameras to digitally sign the images they take. Even before AI slop, it was useful to avoid manual alterations. AI makes it all too easy, so it makes sense.

However, this will certify only the original image. I think the missing part of this is additional layers of certification which allow some image editing (e.g., rotating, contrast, etc.) yet clearly document that the image was modified and link to the original image ID. Kind of like a signed git log.

xg15 1 hour ago | parent

EXIF data is stripped for a good reason - because it can be a privacy hazard. Suddenly this plays no role anymore?

doc_ick 1 hour ago | parent

Ontop of this, including a photo edit history in a photo including the original photo would increase the size of a photo to be completely unusable or unshareable.

xg15 1 hour ago | parent

I understood the GP so that only some unique ID or hash of the original image would be included, not the image itself. Basically like the commit chain of Git but without the actual content blobs.

You could use this data to prove that image B is an edit of image A if you already have both A and B.

I still think this is a bad idea, because this all requires the images to have some sort of ID - and that seems like a prime target for tracking.

lokar 26 minutes ago | parent

You can publish a fully stripped image (as people do now for exif), and retain the original

stvltvs 1 hour ago | parent

Signing the raw image data wouldn't require also signing the EXIF metadata. For privacy, you could later strip out everything except the raw image and the camera's signature and still prove that the image is unaltered.

smalltorch 37 minutes ago | parent

I think he's saying the existence of a camera signature is the privacy issue maybe.

lokar 27 minutes ago | parent

You can remove it all.

If authenticity later becomes an issue you can produce the original.

hamdingers 36 minutes ago | parent

In the contexts where you need to prove an image is a real unaltered photograph (court cases, news media, science, etc) privacy is usually not a concern.

Nobody cares if your social media photos are edited, they probably are, it's fine.

ranger_danger 1 hour ago | parent

There will always be a way around it. There are even open-source alternative/hacked firmwares for professional DSLR cameras where tampering with the signing may be possible.

And this still doesn't help any other kind of image e.g. screenshots, photo of a screen etc. that can make the camera signatures largely pointless depending on the context.

stvltvs 1 hour ago | parent

The idea is to be able to prove that a photo you took was captured by a camera, not generated. That would be helpful in the context of a disputed news story, a court case, etc.

Would that ever be relevant for a screenshot?

ranger_danger 28 minutes ago | parent

Yes in multiple ways, and there's probably more than this:

It's relevant that a screenshot doesn't have a signature, in the case that you want to remove any "proof" or tracking info from a real photo when uploading an image. Maybe I don't want people to know what brand/model of camera I use.

And it's relevant if a screenshot did have a signature if you want to "prove" that the screenshot itself hasn't been tampered with after the fact.

teravor 50 minutes ago | parent

if such a method gains traction then so will the effort to bypass it. either by stealing private keys or just projecting light onto the sensor.

mandolingual 31 minutes ago | parent

Even if it's flawed, adding any friction at all to the effort of deception is a positive step.

zvr 25 minutes ago | parent

People may be interested in the work of the Coalition for Content Provenance and Authenticity (C2PA) https://c2pa.org/

treyd 45 minutes ago | parent

I don't understand why few people are pointing out the obvious vulnerability here that you can control the wires going into the photosensor controller and pretend that the photosensor is capturing whatever image you want. I imagine it's not exactly trivial to do this, but a grad student with an FPGA could probably figure it out.

figmert 40 minutes ago | parent

Or, as the author said, you can just photograph an AI generated picture, and that will work too.

TedDoesntTalk 39 minutes ago | parent

Even easier is to just take a picture of an AI-generated picture.

Lammy 18 minutes ago | parent

In the future, people willingly surveil themselves 24/7 with cryptographic proof, because fake images and video will be so good that it will be the only way to prove what one didn't do. Total Information Awareness achieved :D