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Comment by prennert | Hacker News Reader

I posted this, because I find this very cool. But before using this in production anywhere, I wanted to find out how secure people think this is and what should be done regarding audits etc before it can be used in a serious system.

Does anyone have insight into the auditing process at openssh?

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> I wanted to find out how secure people think this is

It depends on what do you compare this with. PKCS/OpenPGP smartcard is protected by a PIN (6 digits min, 3 tries and it locks itself out) and then touch on each use (with Yubikey).

U2F on the other hand it just protected by touch so anyone having the token can authorize themselves. (Sites usually use it in conjunction with username/password that is "something you know").

On the yet another hand I didn't review the implementation and would welcome corrections here.

Good point.

When I used a Yubikey as a Smartcard it did in fact prompt for a passphrase. But that was via PKCS/SmartCard method, not U2F.

U2F/FIDO2 supports user verification (UV) in addition to user presence (UP). So you should be able to do the same, but I haven't tested if the current implementation supports it.

Their own documentation suggests these are the same thing and both refer to the need to press a button or close a contact or whatever:

Generically, the term “User Verification” may also refer to this “Test for User Presence”

from e.g.

https://fidoalliance.org/specs/fido-security-requirements-v1...

Weird, this spec has a little bit of a different terminology. I think it's better to refer to CTAP2 or WebAuthn directly. UV refers to PIN or biometric, it's in addition to UP.

https://fidoalliance.org/specs/fido-v2.0-ps-20190130/fido-cl...

Note that CTAP and WebAuthn are newer and although they contain U2F for backwards compatibility reasons U2F doesn't contain CTAP2 and WebAuthn. U2F is also surprisingly simple protocol (two specs on FIDO site).

Yes, and exactly because FIDO2 is backward compatible with U2F the definition of UV can't be ambiguous, otherwise you could have older U2F keys that pretend to do FIDO2-UV when in fact they aren't.

Yubikey just announced a key with a fingerprint reader today.

Besides the point that it wouldn't be a secure replacement for a password/PIN, I wonder if it would have support for multiple valid fingerprints. Some time ago, I got cut on my finger and was having some trouble getting my fingerprint recognized. It would suck to get locked out of stuff because of a cut.