> When it is present, WebAuthn attestation tells the site the make and model of the authenticator, identified by its AAGUID, with a certificate chain from the vendor to back it up. It says nothing about your OS, your browser, your extensions, whether your phone is rooted or jailbroken, your firmware version, or even what colour it is.
"Model of the authenticator" could say almost everything about these if the model was let's say "Google Pixel 10". TEE would refuse to sign the attestation if the bootloader was unlocked / AVB didn't verify.
YubiKey attestation is not a problem because the device doesn't work against me in such a way it would require installing custom software on it. And even if YubiKey went crazy, they're not a monopoly.
Situation with smartphones is very much different..
"Model of the authenticator" could say almost everything about these if the model was let's say "Google Pixel 10". TEE would refuse to sign the attestation if the bootloader was unlocked / AVB didn't verify.
YubiKey attestation is not a problem because the device doesn't work against me in such a way it would require installing custom software on it. And even if YubiKey went crazy, they're not a monopoly.
Situation with smartphones is very much different..