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Re: [TLS] Call for consensus: Removing DHE-based 0-RTT

Eric Rescorla <ekr@rtfm.com> Thu, 31 March 2016 15:06 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Thu, 31 Mar 2016 08:05:20 -0700
Message-ID: <CABcZeBN5G7Mo+UGNn=K=_STweziub_zCJsrKER3GZ-XZR_rsgQ@mail.gmail.com>
To: Hannes Tschofenig <hannes.tschofenig@gmx.net>
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Subject: Re: [TLS] Call for consensus: Removing DHE-based 0-RTT
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Hannes,

No, the proposal is to remove both EC and non-EC DHE 0-RTT profiles.

The only way to do 0-RTT would be with a PSK (in both PSK and PSK-(EC)DHE
modes).
However, this would include PSKs established via a previous session, i.e.,
resumption-PSK.

-Ekr


On Thu, Mar 31, 2016 at 5:20 AM, Hannes Tschofenig <
hannes.tschofenig@gmx.net> wrote:

> Hi Sean,
>
> just to make sure that I properly understand the question: You are
> suggesting to remove the DHE support but not the ECDHE support from the
> 0-RTT exchange.
>
> Removing the DHE support is fine for us (at ARM) since we are focused on
> ECDHE for IoT devices. The DTLS/TLS profile and other IETF
> specifications very much focused on ECDHE and do not consider the use of
> DHE.
>
> Ciao
> Hannes
>
>
> On 03/29/2016 03:11 PM, Sean Turner wrote:
> > All,
> >
> > To make sure we’ve got a clear way forward coming out of our BA
> > sessions, we need to make sure there’s consensus on a couple of
> > outstanding issues.  So...
> >
> > There also seems to be (rougher) consensus not to support 0-RTT via
> > DHE  (i.e., semi-static DHE) in TLS 1.3 at this time leaving the only
> > 0-RTT mode as PSK. The security properties of PSK-based 0-RTT and
> > DHE-based 0-RTT are almost identical, but 0-RTT PSK has better
> > performance properties and is simpler to specify and implement. Note
> > that this does not permanently preclude supporting DHE-based 0-RTT in
> > a future extension, but it would not be in the initial TLS 1.3 RFC.
> >
> > If you think that we should keep DHE-based 0-RTT please indicate so
> > now and provide your rationale.
> >
> > J&S
> >
> > _______________________________________________ TLS mailing list
> > TLS@ietf.org https://www.ietf.org/mailman/listinfo/tls
> >
>
>
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