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Re: [TLS] Security review of TLS1.3 0-RTT

Nico Williams <nico@cryptonector.com> Fri, 05 May 2017 16:45 UTC

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Date: Fri, 05 May 2017 11:45:47 -0500
From: Nico Williams <nico@cryptonector.com>
To: Benjamin Kaduk <bkaduk@akamai.com>
Cc: "tls@ietf.org" <tls@ietf.org>
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Subject: Re: [TLS] Security review of TLS1.3 0-RTT
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On Fri, May 05, 2017 at 12:07:09AM -0500, Benjamin Kaduk wrote:
> On 05/03/2017 09:33 PM, Blumenthal, Uri - 0553 - MITLL wrote:
> > P.S. Care to name (another :) one security-related protocol that
> > doesn't provide replay protection?
> 
> Some of the earlier uses of Kerberos are subject to replay (hence
> kerberos implementations can end up providing replay caches to try and
> help, which are not perfect and slow to boot).  More modern exchanges
> that use GSS acceptor subkeys are not subject to replay, though.

We might be getting far afield now, but if you're not using "mutual
auth" then GSS/Kerberos will look a lot like TLS 1.3 0-rtt.  GSS apps
that want that need to be careful, just as TLS 1.3 0-rtt apps.

Also, even for the 1-rtt case, GSS/Kerberos supports early (0-rtt) data.

Nico
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