crypto frobs

Tue Mar 24 02:08:58 UTC 2020

On Mon, Mar 23, 2020 at 18:50 William Herrin <bill at herrin.us> wrote:

> On Mon, Mar 23, 2020 at 5:16 PM Warren Kumari <warren at kumari.net> wrote:
> > Well, yes and no. With a Yubiikey the attacker  has to be local to
> > physically touch the button[0] - with just an SSH key, anyone who gets
> > access to the machine can take my key and use it. This puts it in the
> > "something you have" (not something you are) camp.
>
> Hi Warren,
>
> They're both "something you have" factors. The yubi key proves
> possession better than the ssh key just like a long password proves
> what-you-know better than a 4-digit PIN. But the ssh key and the yubi
> key are still part of the same authentication factor.
>
>
> > Not really -- if an attacker steals my laptop, they don't have the
> > yubikey (unless I store it in the USB port).
>
> You make a habit of removing your yubi key from the laptop when nature
> calls? No you don't.
>
>
> > If they *do* steal both,
> > they can bruteforce the SSH passphrase, but after 5 tries of guessing
> > the Yubikey PIN it self-destructs.
>
> What yubikey are you talking about? I have a password protecting my
> ssh key but the yubikeys I've used (including the FIPS version) spit
> out a string of characters when you touch them. No pin.
>

The yubikey does many things depending on how it’s configured. None of mine
use the touch to spit out OTP mode, that is the factory mode though yes.
Other modes can be password protected (it uses the PIN nomenclature which
is confusing, it definitely accepts ASCII and nay even take binary data as
a PIN depending on mode of operation) — it can present as industry standard
smart card ( I have one with a pin/password for code signing in Visual
Studio f/ex...along with a backup kept locked elsewhere)

>
> Regards,
> Bill Herrin
>
>
> --
> William Herrin
> bill at herrin.us
> https://bill.herrin.us/
>
-- 

"Genius might be described as a supreme capacity for getting its possessors
into trouble of all kinds."
-- Samuel Butler
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