Ancestors

Written by Chris Needham on 2024-10-17 at 09:44

An interesting couple of days talking content authenticity and C2PA with news industry folks

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Written by Jeffrey Yasskin on 2024-10-17 at 14:10

@chrisneedham What's your impression of its usability and generality? I heard a rumor that it was being accidentally designed for only large entities to use, which would be a shame.

I imagined that it would have two modes: 1 where the hardware has a secure element that signs pictures (and we collectively distrust hardware that gets hacked), and a second where anyone can create a private key and assert modifications with it (and we aggregate and distrust folks who lie)?

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Written by Jeffrey Yasskin on 2024-10-17 at 14:20

@chrisneedham In (at least) the second mode, we'd need at least one governance body (kinda like a certificate authority, maybe) to help everyone decide whether to trust the signing keys.

[#]KnowledgeCommons...

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Written by Chris Needham on 2024-10-17 at 14:48

@jyasskin There are two main strands to it. One is C2PA itself which is about signed metadata that's bound to content (images, video, audio, anything with a container format), where the signing is done by the hardware or software used to capture and edit. This creates a chain of metadata for how that content got created, what edits were made, etc. It's not about saying what's "true" or not, just verifiably how it came to be

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Written by Jeffrey Yasskin on 2024-10-17 at 14:59

@chrisneedham I stumbled over "signing is done by the... software". Software can't sign anything in a trustworthy way; only the entity running the software can sign things. Is there an assumption here that only cloud services can be trusted in this ecosystem, and where does that leave people who edit photos on their own hardware?

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Written by Chris Needham on 2024-10-17 at 15:12

@jyasskin AIUI, with C2PA images can be signed by a camera, or maybe a phone camera app if running on a "trusted" hardware / platform. I don't think it relies on limiting to cloud services. Similarly, a native editor app could include its signing cert. But ... reverse engineering, how it works with OSS tools??

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Toot

Written by Jeffrey Yasskin on 2024-10-17 at 17:21

@chrisneedham A native editor app cannot include its signing cert when distributed to customer machines, even if it's closed source. :) If that signing cert is trusted, and the software has restrictions that a malicious user might want to get around, the signing cert will quickly be extracted and used to sign content generated without those restrictions.

If the WG thinks they're going to safely distribute signing keys in software, we need to get them some security review ASAP.

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Descendants

Written by Chris Needham on 2024-10-17 at 17:26

@jyasskin Right... So I don't know the details, but I fully agree with the need for review

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