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I don't like passkeys

853 points · 819 comments · ethanhawksley

  1. drtz · · focus · HN ↗
    Passkeys do marginally improve security against MITM and phishing attacks, but they are primarily for protecting the lowest common denominator from themselves: people who re-use passwords and/or don't use a password manager.

    If you use multiple devices throughout the day, registering passkeys in all of these systems becomes a big headache with O(m*n) complexity, so putting the passkeys in a password manager is the only realistic solution. But this still breaks the login flow for a very common use case: how do I log in on a device that I don't own? With a password in a password manager I at least have the option of manually typing the password.

    The biggest problem, though, is how users are pushed into it without any warning or knowledge of what they're signing up for. I've accidentally set up passkeys just by clicking an okay button a few times in the past and had to go back and figure out how to undo it after being blocked from login on another computer (which computer was I on again?).

    1. judge2020 · · focus · HN ↗
      > how do I log in on a device that I don't own?

      This is solved by passkey-implementing software and devices (with Bluetooth) allowing you to log in with a QR code (Webauthn via CTAP hybrid transport). iOS and Android support this, and it’s generally not a locked-down thing if other devices wanted to do it too.

      The only use case left is in “how do I login if all my devices are stolen/fall into a body of water” in which there really isn’t an answer beyond “get (a|your) device back, sign back into your password manager, use that to get back into critical accounts”.

      1. 201984 · · focus · HN ↗
        What if the computer you want to log in on doesn't have Bluetooth? Probably most public computers (like ones in libraries) don't have it.
        1. limagnolia · · focus · HN ↗
          The website should display a qr code you can scan with your phone that allows you to then login, unfortunately a lot of sites don't implement this, and some don't implement backup codes. This isn't the fault of passkeys per se, but of poor implementations.
          1. wpollock · · focus · HN ↗
            > The website should display a qr code you can scan with your phone that allows you to then login...

            A malicious website can display a QR code too. I think this "feature" could cause some of the security issues that passkesys were intended to solve.

            I use Keepass and the free tier of Dropbox, to keep my passwords strong and available across multiple devices. (Dropbox not required, you can store the database on a thumb drive.) Backups are no problem.

            Keepass (or KeepassXC) stores other data as well, including the correct URLs for sites. So my workflow is simply to click the URL from within Keepass, copy the username and password, and paste them into the login screen. So easy even an adult can do it! (Humor attempt)

            For convenience, Keepass database can be unlocked with either a password or biometrics (your fingerprint).

            (Not affiliated with Keepass, just a happy longtime user.)

            1. dwaite · · focus · HN ↗
              Yes, the passkey flow QR code contains a public key, and a local key exchange is done over bluetooth to prove proximity. That is used to set up a confidential channel.

              That means attackers need more than to display a QR code, they also need a local presence (radio).

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