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

Nico Williams <nico@cryptonector.com> Mon, 23 March 2015 08:48 UTC

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Date: Mon, 23 Mar 2015 03:47:16 -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 Sun, Mar 22, 2015 at 02:49:28PM -0700, Eric Rescorla wrote:
> Now consider what happens when the server reboots and loses its
> state. You don't want to reject every client 0-RTT connection so
> instead what you do is you ignore the client's initial data sent in
> the first flight. Since the ServerHello provides a new Random value,
> any data the client sends in subsequent flights has the usual
> anti-replay protection.

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".

Nico
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