[39236] in Kerberos
Re: help with OTP
daemon@ATHENA.MIT.EDU (Ken Hornstein via Kerberos)
Wed Apr 26 12:35:22 2023
Message-ID: <202304261629.33QGTlJ8015728@hedwig.cmf.nrl.navy.mil>
To: Matt Zagrabelny <mzagrabe@d.umn.edu>
cc: kerberos <kerberos@mit.edu>
In-Reply-To: <CAOLfK3X+3LSdOfA0vpDDiPi3RC7GUb73+jZTYje7sjDfQVu96g@mail.gmail.com>
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Date: Wed, 26 Apr 2023 12:29:47 -0400
From: Ken Hornstein via Kerberos <kerberos@mit.edu>
Reply-To: Ken Hornstein <kenh@cmf.nrl.navy.mil>
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>Since I am currently only interested in anonymous auth, I thought I
>could skip that directive. But alas:
Right, so, here's where my limited knowledge of FAST comes into play.
As I understand it, you need to be able to use a trusted key to
authenticate with the KDC to to create the FAST channel. Your options
are using an already-existing key (such as a host key) or anonymous
PKINIT. But the "anonymous" part of anonymous PKINIT only refers to the
CLIENT being anonymous; you still need the client to be able to verify
the KDC's certificate (otherwise anyone could pretend to be your KDC and
you could end up sending your OTP output to them, which would be bad).
That's the piece you were missing. Once you have the FAST channel set
up then you can use that to securely send the OTP response.
I see in a later message you got it working; great! Just FYI in case
anyone else asks, the key line in that trace output was this:
[1185088] 1682519355.427424: Processing preauth types: PA-PK-AS-REQ
(16), PA-FX-FAST (136), PA-ETYPE-INFO2 (19), PA-PKINIT-KX (147),
PA-ENCRYPTED-CHALLENGE (138), PA_AS_FRESHNESS (150), PA-FX-COOKIE
(133), PA-FX-ERROR (137)
You're missing PA-OTP-REQUEST, which was because (as you discovered)
that plugin wasn't installed. But that requires a lot of Kerberos
knowledge to get to that point :-/
It does occur to me a useful addition to kinit might be a flag that
means "authenticate using anonymous PKINIT and then use those
credentials as a FAST armour credential cache" so you wouldn't have
to muck around with juggling credential caches.
--Ken
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