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Re: [TLS] 0-RTT and Anti-Replay

Viktor Dukhovni <ietf-dane@dukhovni.org> Mon, 23 March 2015 17:14 UTC

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Date: Mon, 23 Mar 2015 17:14:39 +0000
From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: Re: [TLS] 0-RTT and Anti-Replay
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On Mon, Mar 23, 2015 at 07:07:33PM +0200, Ilari Liusvaara wrote:

> > A connection on which the initial data was lost is broken.  Signalling
> > such loss is simplest by dropping the connection.
> 
> No, it isn't. The client will need to handle 0-RTT being lost
> anyway.

Naturally before disconnecting, the server stack should send an
appropriate alert.  But since clients should only be configured
for 0-RTT with application protocols where the server is required
to support 0-RTT, there's no point in falling back.

I don't see 0-RTT as an "opportunistic" feature.  I see it as
support for latency-sensitive idempotent applications in which it
is always used.  Eliminating fallback to 1-RTT avoids much complexity.

-- 
	Viktor.

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