[julvo]

I don't see how a blockchain helps with problems arising from deepfakes. What's key for the solution is signing the content on the physical device, aka public key cryptography. To my understanding, a blockchain solves the problem of agreeing on a temporal order of events (eg. transactions), which I don't think is critical in the case of deepfakes.

[jsutton]

Temporal order is absolutely critical in determining the truth of an event, as deepfakes could be used after the fact to distort the facts and mislead a viewer. Blockchain allows for the use of public key cryptography with a guarantee of the time in which the video/document/etc was created.

[julvo]

If we trust the device manufacturer to only sign genuinely recorded videos, couldn't we also trust them to sign the videos with a correct timestamp?

[jsutton]

Where would manufacturers store and display these timestamps? Would each manufacturer host their own proofs, or share a database together? Who would pay for that, indefinitely? The economic reality is that no one would ever pay the costs for such a ledger of all video timestamps. This is where blockchain is necessary.