The authors concern is primarily about attested and user-verified passkeys.

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[–] 17 points 3 days ago* (3 children)

I'm taking a wait-and-see approach to passkeys, myself, but the author omits what seems to be the greatest advantage of passkeys over a password + TOTP combo from a user perspective: they offer resistance against phishing attacks.

TOTP protects you against attacks where an attacker manages to get hold of your password and attempts to log in remotely, since the TOTP presents an additional barrier, and you're probably not going to respond to a random text or email that says, "Uhhhh can you send me a code from your authentication app real quick?". But if you get phished and unknowingly attempt to log into a malicious server, you'll happily give them your password and TOTP.

With passkeys, the challenge presented by a website is cryptographically signed and tied to the domain for which you originally generated the passkey. Even if you end up on a phishing website, if the site sends you a challenge that is either not originating from the domain associated with your passkey (e.g. from the phishing domain itself) or not originating from the domain you're currently on (as would be the case if the phishing server were passing on a challenge from the legitimate domain), it can be trivially detected and refused by the client.


Whether security against that particular kind of attack is worth the privacy/control trade-offs to you is a personal decision^[I recognize that this may stop being a decision that I'm even allowed to make, which is kinda the whole point of the article, but I'm just talking in the near term.]—thus far, I've decided it's not worth it. My policy has long been to never click links in email/texts/etc. that will require authentication—I go directly to the website, sign in, and then navigate to the indicated page. That wouldn't protect against an attack where a malicious actor gains control of the legitimate website, but neither would a passkey, to my knowledge.

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  • [–] 5 points 2 days ago (2 children)

    Not omitted, article mentions that passkey validation is domain-bound, and thus resistant to MITM.

    Maybe was updated?

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  • [–] 2 points 2 days ago (1 child)

    Oh huh, I missed that—thanks for pointing that out! In my defense, it is literally in a footnote on the last sentence of the article (I was reading the footnotes, for the record, but I think I missed that one because I got distracted by looking into the Game Boy TOTP when it was mentioned again). In that footnote, the author says that they "feel [they] have made a compelling case for passkeys in this article" even without mentioning the resistance to MITM, but tbh, if I were someone reading this article I'd be like, "Okay, so it's basically a password but it comes with possible privacy drawbacks? Why would I want to use that?"

    All the stuff about how passkeys can be configured to require PINs or biometrics at the time of use is equally true of password managers, so I don't really see how those are selling points, and the fact that they can be configured to allowing logging in without any interaction doesn't seem like much of a benefit when password managers can also autofill. The only distinctive bit is the invasive attestation option, which the author has misgivings about (as do I).

    Again, I personally am not going to be using passkeys for the foreseeable future, but it seems odd to bury the single most obvious benefit of passkeys as far down as physically possible. Hell, even the explanation is probably impenetrable for a non-technical reader, which seems to be the intended audience. It says "they are (in most use cases) domain-bound, meaning they are resistant to what are called Man-In-The-Middle attacks", but it doesn't give context about what MITM attacks are or whether they're a serious concern. Even for someone who knows what a MITM attack is, you still have to infer what specific kind of MITM attack it protects against and how that protection is accomplished.


    Scanning this comment over it seems a little hostile, which is not my intention, so please don't take it that way! I genuine appreciate you pointing that out, and it's a reminder to be more careful before shooting my mouth off about articles with footnotes bleh

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