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Re: [TLS] Security review of TLS1.3 0-RTT

Nico Williams <nico@cryptonector.com> Wed, 03 May 2017 18:18 UTC

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Date: Wed, 03 May 2017 13:16:45 -0500
From: Nico Williams <nico@cryptonector.com>
To: Eric Rescorla <ekr@rtfm.com>
Cc: Daniel Kahn Gillmor <dkg@fifthhorseman.net>, TLS WG <tls@ietf.org>
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Subject: Re: [TLS] Security review of TLS1.3 0-RTT
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On Tue, May 02, 2017 at 09:41:00PM -0700, Eric Rescorla wrote:
> On Tue, May 2, 2017 at 9:22 PM, Nico Williams <nico@cryptonector.com> wrote:
> 
> > On Tue, May 02, 2017 at 04:41:52PM -0700, Eric Rescorla wrote:
> > > On Tue, May 2, 2017 at 4:02 PM, Nico Williams <nico@cryptonector.com>
> > wrote:
> > > > On Tue, May 02, 2017 at 03:53:48PM -0700, Eric Rescorla wrote:
> > > > > It's not XOR. It's addition mod 2^32. That's important because the
> > > > > *difference*
> > > > > between the ticket replay times is directly observable anyway.
> > > >
> > > > Computationally there's no real difference between that and XOR.
> > >
> > > What information do you believe you are gathering here?
> >
> > I believe the attack described is finding the time of the session's
> > establishment.
> 
> Hmm.... Can you walk me through how you think that works?

Well, I hadn't done it myself.  I see now though that the attack doesn't
work.

I would still prefer proper encryption.  But this works.

Nico
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