Deepfakes are about impersonating the person in the video, fake news is… Well, just someone lying. Signatures are meant to verify the source of information, not the contents of it.

Simple example, we can be nearly 100% confident that the person posting tweets under the Trump account is (atleast authorized by) Trump. Doesnt stop him from lying nor uploading a deepfake video.

I don’t understand how this will help deep fake and fake news.

Like, if this post was signed, you would know for sure it was indeed posted by @[email protected], and not by a malicious lemm.ee admin or hacker*. But the signature can’t really guarantee the truthfulness of the content. I could make a signed post that claiming that the Earth is flat - or a deep fake video of NASA’a administrator admitting so.

Maybe I’m missing your point?

(*) unless the hacker hacked me directly