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Comment by WJW | Hacker News Reader

Perhaps I am being too cynical, but how do you protect this scheme against hostile actors?

Bits don't have color after all (see https://ansuz.sooke.bc.ca/entry/23 if you don't get this reference) and it would be fairly trivial to manually alter such media types to anything you want. For example if someone posts a `ai_edited(human_created(photo))` online, it would be straightforward to take the pixels of the photo and re-publish them as a "new" image with only the `human_created(photo)` tags. You could also randomly start adding `ai_edited` tags to things you want discredited, etc.

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Ah no problem. Just a sketch..

Looking at C2PA, I'd now use "claim" to describe those tags. They're short and human readable but not self-contained. They'd have to be authenticated with tool signing to be very useful. As it also emphasizes, it's about establishing trust for a domain, eg can Samsung photo signing be trusted?

Eg for a normal photo, your device could sign it with.. and OTP coordinated with the manufacturer? Then include the signing metadata in the EXIF tags of the image. To validate, you send the image+signed_claims to manufacturer and they know the OTPs (?) and can verify the signing

Doesn't make it unforgeable, bc you could intercept the hardware otp/signing protocol.. but would raise the cost quite a bit. Maybe with frequent key resets you can raise this further

Something like that sounding more useful?

The analogue hole makes this all pointless. Ultimately at some point down the chain there's regular camera sensors that can be replaced with anything you want.

Exactly. This won't stop any determined bad actor, if anything, it's just going to boost their credibility when they inevitably come up with a bypass that allows them to sign any piece of media as "authentic" (in a few days or weeks after a device implementing such a scheme is released).

What then? 99.9% of honest actors are paying with their privacy[1] and usability again, while remaining 0.1% of dishonest actors are using a bypass - which sounds a lot like piracy and various DRM schemes. We've been here before, and it never works.

[1] While this might not be an immediate goal, I think it's pretty obvious any such scheme would eventually be corrupted to encode a traceable device ID into every photo and video taken with the device - to protect the children and stop CSAM, of course!

Hmm, how about watermarking the photo with some function of the OTP? (like bit steganography; invisible to normal human use)

Seems to preserve easy checking by device manufacturer, but not immediately clear to me how to replace the sensor in a way that gets a signed image.

And if it seems like a bit of trouble, I think it's still worth consideration by the manufacturer, as a feature for their images and support of a community of users who want to produce images that can be so validated

A business of Internet-connected cameras which automatically hash and commit the hashes of photos they take, unaltered, would give that claim much more credence. I suppose this idea doesn't come up all that often because of the hardware changes involved, but I could see this being very handy for anyone who needs to verify that photos are real in a professional capacity.

>Doesn't make it unforgeable, bc you could intercept the hardware otp/signing protocol

If hardware driven attestation like that used by Xbox One is used, intercepting the protocol becomes impossible.

Preventing computing hardware from running unauthorized processes is already a largely solved problem.

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