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

Nico Williams <nico@cryptonector.com> Mon, 23 March 2015 17:20 UTC

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Date: Mon, 23 Mar 2015 12:19:55 -0500
From: Nico Williams <nico@cryptonector.com>
To: Eric Rescorla <ekr@rtfm.com>
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Subject: Re: [TLS] 0-RTT and Anti-Replay
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On Mon, Mar 23, 2015 at 08:11:59AM -0500, Eric Rescorla wrote:
> On Mon, Mar 23, 2015 at 3:47 AM, Nico Williams <nico@cryptonector.com>
> wrote:
> > This is an optimization.
> >
> > If the server loses its replay state then it must cause every 0-RTT
> > connection to become a 1-RTT connection.  There's no question of "want".
> 
> Maybe I wasn't clear. When I said "reject" I meant "hard-fail" rather than
> make it 1-RTT.

Sorry it wasn't clear to me.  Is there any reason that fallback to 1-RTT
is not feasible?

For context, I'm proposing similar fallbacks (but for other reasons) for
Kerberos (which never had such a fallback).  This has proven desirable
in the context of Kerberos, and so I suspect it will be for TLS.

Obviously I'm missing some of the TLS 0-RTT context.

Nico
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