You read my mind. I'd love if it could be rooted in a Yubikey.
Decoupling the "signing" and "verifying" parts seem like a good idea. As random Person signs something, how someone else figures out how to go trust that signature is a separate problem.
FIDO2 and Yubico helped develop the new W3C WebAuthn standard: https://en.wikipedia.org/wiki/WebAuthn
But WebAuthn does not solve for WoT or PKI or certificate pinning.
> Decoupling the "signing" and "verifying" parts seem like a good idea. As random Person signs something, how someone else figures out how to go trust that signature is a separate problem.
Someone can probably help with terminology here. There's identification (proving that a person has the key AND that it's their key (biometrics, challenge-response)), signing (using a key to create a cryptographic signature – for the actual data or a reasonably secure cryptographic hash of said data – that could only could have been created with the given key), signature verification (checking that the signature was created by the claimed key for the given data), and then there's trusting that the given key is authorized for a specific purpose (Web of Trust (key-signing parties), PKI, ACME, exchange of symmetric keys over a different channel such as QKD) by e.g. signing a structured document that links cryptographic keys with keys for specific authorized functions and trusting the key(s) used to sign said authorizing document.
Private (e.g. Zero Knowledge) blockchains can be used for key exchange and key rotation. Public blockchains can be used for sharing (high-entropy) key components; also with an optional exchange of money to increase the cost of key compromise attempts.
There's also WKD: "Web Key Directory"; which hosts GPG keys over HTTPS from a .well-known URL for a given user@domain identifier: https://wiki.gnupg.org/WKD
Compared to existing PGP/GPG keyservers, WKD does rely upon HTTPS.
TUF is based on Thandy. TUF: "The Update Framework" does not presume channel security (is designed to withstand channel compromise) https://en.wikipedia.org/wiki/The_Update_Framework_(TUF)
The TUF spec doesn't mention PGP/GPG: https://github.com/theupdateframework/specification/blob/mas...
There's a derivative of TUF for automotive applications called Uptane: https://uptane.github.io
The Bitcoin article on multisignature; 1-of-2, 2-of-2, 2-of-3, 3-of-5, etc.: https://en.bitcoin.it/wiki/Multisignature