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Re: [TLS] Remove DH-based 0-RTT

Andrei Popov <Andrei.Popov@microsoft.com> Tue, 23 February 2016 20:02 UTC

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From: Andrei Popov <Andrei.Popov@microsoft.com>
To: Martin Thomson <martin.thomson@gmail.com>, Wan-Teh Chang <wtc@google.com>
Thread-Topic: [TLS] Remove DH-based 0-RTT
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Date: Tue, 23 Feb 2016 20:02:10 +0000
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Subject: Re: [TLS] Remove DH-based 0-RTT
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For general-purpose TLS stacks that have to support PSK anyway (and therefore already deal with PSK persistence issues), removing DH-based 0-RTT is a significant simplification.

Cheers,

Andrei

-----Original Message-----
From: TLS [mailto:tls-bounces@ietf.org] On Behalf Of Martin Thomson
Sent: Tuesday, February 23, 2016 11:39 AM
To: Wan-Teh Chang <wtc@google.com>
Cc: tls@ietf.org
Subject: Re: [TLS] Remove DH-based 0-RTT

On 23 February 2016 at 11:24, Wan-Teh Chang <wtc@google.com> wrote:
> It seems sufficient to just ban client authentication in replayable 
> DH-based 0-RTT. Why remove DH-based 0-RTT altogether?

On the grounds that it is more complex to analyze, build, and test.
And given that deferring the feature does no significant harm to those who want it.

I acknowledge that persistence of secrets on clients is a material difference between that an PSK-based 0-RTT.  I just don't think that it's a good enough reason to pay for what is a relatively expensive feature.

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