Passkeys are built on the FIDO2 standard (CTAP2 + WebAuthn standards). They remove the shared secret, stop phishing at the source, and make credential-stuffing useless.
But adoption is still low, and interoperability between Apple, Google, and Microsoft isn’t seamless.
I broke down how passkeys work, their strengths, and what’s still missing
Well yes, that is a huge one. I know people who when faced with Google’s credible password suggestion say “hell no, I could never remember that”, then proceed to use a leet-speak thinking computers can’t guess those because of years of ‘use a special character to make your password secure’. People at work giving their password to someone else to take care of someething because everything else is a pain and the stakes are low to them. People being told their bank is using a new authentication provider and so they log dutifully into the cited ‘auth provider’, because this is the sort of thing that (generally not banks) do to people.
Exactly, it mitigates, but still a gap. If they phish for your bank credential, you give them your real bank password. It’s unique, great, but the only thing the attacker wanted was the bank password anyway. If they phish a TOTP, then they have to make sure they use it within a minute, but it can be used.
From the user perspective that knows they are using machine generated passwords, yes, that setup is redundant. However from the service provider perspective, that has no way of enforcing good password hygiene, then at least gives the service provider control over generating the secret. Sure a ‘we pick the password for the user’ would get to the same end, but no one accepts that.
But this proves that if you are fanatical about MFA, then TOTP doesn’t guarantee it anyway, since the secret can be stuffed into a password manager. Passkey has an ecosystem more affirmatively trying to enforce those MFA principles, even if it is, ultimately, generally in the power of the user to overcome them if they were so empowered (you can restrict to certain vendor keys, but that’s not practical for most scenarios).
My perspective is that MFA is overblown and mostly fixes some specific weaknesses: -“Thing you know” largely sucks as a factor, if I human can know it, then a machine can guess it, and on the service provider there’s so much risk that such a factor can be guessed at a faster rate than you want, despite mitigations. Especially since you generally let a human select the factor in the first place. It helps mitigate the risk of a lost/stolen badge on a door by also requiring a paired code in terms of physical security, but that’s a context where the building operator can reasonably audit attempts at the secret, which is generally not the case for online services as well. So broadly speaking, the additional factor is just trying to mitigate the crappy nature of “thing you know” -“Thing you have” used to be easier to lose track of or get cloned. A magstripe badge gets run through a skimmer, and that gets replicated. A single-purpose security card gets lost and you don’t think about it because you don’t need it for anything else. The “thing you have” nowadays is likely to lock itself and require local unlocking, essentially being the ‘second factor’ enforced client side. Generally Passkey implementations require just that, locally managed ‘second factor’.
So broadly ‘2fa is important’ is mostly ‘passwords are bad’ and to the extent it is important, Passkeys are more likely to enforce it than other approaches anyway.