Tongue in cheek: is public key cryptography the solution to verifying content authorship on the internet? Should all major OSes establish and bundle proof of authenticity for every phrase and image created in them using an input device attached to them?
Gram and Gramp are going to get their keys phished. An LLM screed signed by Gramps stolen key isn't authentic even though it 100% mathematically is. Authenticity is about the mindset and intentions of the creator.