logoalt Hacker News

cortesoft • today at 4:25 PM • 3 replies • view on HN

This may or may not help depending on how technical you are, but at the core a passkey works through public key cryptography, like SSH keys work. Setting up a passkey with a site involves sending a public key to the site, which they store as being owned by your account. Then, to sign in, they use your public key to generate a challenge, you use your private key to solve the challenge, and you respond proving you have the corresponding private key.

This means you never send your private key to the site, so if their database is compromised they only get a public key, which can’t do anything (it is public, after all)

No amount of phishing can get you or your client to hand over your private key, because there is no use case where that is required. There is no possibility of MITM, since your private key is never sent anywhere in any situation.

As for getting locked out of your account, losing your passkey would be the same as losing a password. You would need to follow the site’s password reset flow, and if you can recover from a lost password, you can recover from a lost passkey.


Replies

the__alchemist • today at 4:36 PM

This is a fantastic explanation and analogy. Thank you!

I will poke at this a bit:

> As for getting locked out of your account, losing your passkey would be the same as losing a password. You would need to follow the site’s password reset flow, and if you can recover from a lost password, you can recover from a lost passkey.

Do you think this is one of those scenarios that sounds reasonable at first, but can get torn apart by unknowns, edge cases etc? To use an analogy from a recent HN thread that is stretched a bit, is this like saying "If you use a crypto hardware wallet, you're safe", then reading about compromised hardware wallets due to something outside the assumption set.

➕ show 1 reply
EugenioPerea • today at 5:23 PM

If you own only one device—a mobile phone, like the majority of people in the world—and you lose it, how do you get back into your passkey-protected email account?

➕ show 2 replies
what • today at 5:53 PM

What’s PQ story with passkeys? Considering all the hype that everything needs to be pq safe by 2029 (or whatever), wouldn’t it make sense to delay adoption? Otherwise a db leak would compromise every single account in a pq world.

➕ show 1 reply