We had originally planned to go all-in on passkeys for ONCE/Campfire, and we built the early authentication system entirely around that. It was not a simple setup! Handling passkeys properly is surprisingly complicated on the backend, but we got it done. Unfortunately, the user experience kinda sucked, so we ended up ripping it all out...
Right, but I can’t require a second factor on a different device that operates outside of my primary device’s trust store. I’m sure there is some way to make my desktop hit my phone up directly and ask for fingerprint auth before unlocking the local keystore, but that still depends on the security of my device and my trust store. I don’t want the second factor to be totally locked to the device I’m running on. I want the server to say, “oh, cool, here’s this passkey. It looks good, but we also need a TOTP from you before you can log in,” or “loving the passkey, but I also need you to respond to the push notification we just sent to a different device and prove your identity biometrically over there.” I don’t want my second factor to be on the same device as my primary factor.
I mean you don’t have to authenticate your passkey with biometrics, you can use a password.
I guess I’m not really picking up on what the benefit is you’re going for. You already have a What You Have and a What You Know or What You Are, and you want a second What You Also Have thrown in there. I mean, I guess having that as an option couldn’t hurt. but I also don’t think it’s really necessary.