Passkey is some sort of specific unique key to a device allowing to use a pin on a device instead of the password. But which won’t work on another device.
Now I don’t know if that key can be stolen or not, or if it’s really more secure or not, as people have really unsecure pins.
Passkeys can be phished, it’s just much more difficult than with passwords, TOTP MFA, SMS MFA, other OTPs, or push notification-based MFA (e.g., Duo or the way Microsoft, Apple, and Google push a notification to their app and you confirm and/or enter the key).
Passkey is extremely phishing resistant in the same as Webauthn MFA and U2F MFA are, in that origin checks by the browser prevent attackers from initiating the auth process. But it can still be attacked in these ways:
From memory, passkeys, webauthn, and u2f should prevent over 99% of phishing attacks that are successful without them in place.
There’s also the risk of the passkey itself being compromised, though that level of risk is dependent on your device / how you’re storing your passkeys and isn’t a “phishing” risk.
The main point is all those attacks need to attack the local software or hardware implementation on one of the two ends (or a cert issuer), and even then it’s replay protected so for example an XSS attack lasts only for one session, so it’s more robust.
Correct, but that doesn’t change the fact that “Passkeys can’t be phished” is not true.