Though there are many brands built on trust, whose domain name is very difficult to spoof, that are an exception to this.
Hate on nytimes.com, but you have reasonable confidence the content on that site is written, fact-checked and edited by staff at the New York Times Company.
Like Sports Illustrated? Oh, wait...
They will probably still have human review and higher publishing standards than generic blog spam. But in just a few months or sooner you can no longer safely assume a NYT article was not written by AI.
I tear off the Scooby-Doo mask, and the person is now exposed as being a different person.
You hunt me down (somehow? magically? nothing in PK infrastructure allows this, but let's say you do it) and I say "yes, that's my PK, and yes, I signed that" but how can you then verify I didn't take it from chatGPT and sign it?
That's the entire point of cryptocurrencies. They do that as well as is possible right now in a distributed network, conceding the point about key theft.
I would argue it's not all-or-nothing. Signing would verify the the majority of content from creators that have not had their keys stolen. Adding currency/value to this equation boosts the quality further and discourages spamming "content based marketing" garbage. The obstacles are usability and behavior changes, and also that any given user can now copy/paste LLM prompt responses, of course.
Blockchain may be largely over-hyped, but from this bubble I think important research in zero-knowledge proofs and trust-less systems will one day lead to a solution to this that is private and decentralized, rather than fully trackable and run by mega-corps.
Once you have that, unsigned content or content signed by AIs is easy to spot. Because it would either have no reputation at all, or a poor one.
Signatures are impossible to forge (or sufficiently hard that we can assume so), and easy to verify. Reputations are a bit more work but we could provide some tools for that or search engines and other content aggregators could check things for us. But it all starts with a simple signature. Once you have lots of people signing their work, checking their reputation becomes easy. And the nice thing with a reputation is that people care about guarding it is as well. Reputation is hard to fake; you build it throughout your life. And you stake it with everything you publish.
There's no need for blockchains or any fancy nonsense like that. It might help but it's a bit of a barrier to taking this into use.
This does nothing to guarantee that the content was written or edited by a human. Because of the risk of key theft, it doesn't even guarantee that it was published by the human who signed it.
It is physically, philosophically, and technically impossible to verify the authenticity of digital content. At the boundary between the analog world and the digital world, you can always defraud it.
This is the same reason that no one ever successfully used blockchains for supply-chain authentication. Yes, you can verify that item #523 has a valid hash associated with it, but you can't prove that the hash was applied to item #523 instead of something fraudulent.