I wonder if this will get integrated with WebAuthn. Originally, WebAuthn was supposed to provide a nifty security property: if a client authenticates via WebAut

I wonder if this will get integrated with WebAuthn. Originally, WebAuthn was supposed to provide a nifty security property: if a client authenticates via WebAuthn to a server, that server cannot replay the authentication to another server. This property got lost in the standardization process (I think it was meant to come along with token binding, but token binding mostly flopped). So now WebAuthn has a weaker security property: it verifies that the client thinks it’s talking to the right origin. So WebAuthn protects users who visit a typo-squatting domain, but it does not protect against attackers who can pretend to be the target origin. The latter can happen by, for example, compromising a server certificate private key, obtaining a fraudulent certificate, or using a MiTM CA. A hypothetical WebAuthn using exported identifiers would authenticate the user specifically to the server with which the user is actually communicating. This would work without any guarantees from the CA system, and would even work for local network appliances for which server certificates are currently difficult to impossible to use sensibly.