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Re: [saag] Fw:Fw:New Version Notification for draft-cui-dhc-dhcpv6-encryption-02.txt

Nico Williams <nico@cryptonector.com> Mon, 03 August 2015 16:07 UTC

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Date: Mon, 03 Aug 2015 11:07:34 -0500
From: Nico Williams <nico@cryptonector.com>
To: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Subject: Re: [saag] Fw:Fw:New Version Notification for draft-cui-dhc-dhcpv6-encryption-02.txt
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On Wed, Jul 29, 2015 at 03:19:30PM +0100, Stephen Farrell wrote:
> We do I think have proof that symmetric keying for everything
> fails, thanks to RFC3118, but for all the rest, as far as I know
> we'd just be guessing right now.

Ignoring weak passwords and applying a Kerberos-ish (but EAP-ified,
meaning using IAKERB to authenticate to the infrastructure and then
user-to-user Kebreros to authenticate the NAS to the client) I think
symmetric keying for everything ought to work just fine.  (Also ignoring
the lack of PKCROSS.)

Not that that's something I care to push.  Just sayin'.

Weak passwords obviously are a good argument for a PAKE or for at least
having DH + server authentication, so PK does seem necessary, yes, but
mostly for that reason, and for the bootstrapping of cross-domain trusts
that a purely-symmetric Needham-Schroeder protocol has trouble with.

Nico
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