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

Colm MacCárthaigh <colm@allcosts.net> Tue, 02 May 2017 17:51 UTC

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From: Colm MacCárthaigh <colm@allcosts.net>
Date: Tue, 02 May 2017 10:48:29 -0700
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To: Nico Williams <nico@cryptonector.com>
Cc: 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 2, 2017 at 10:39 AM, Nico Williams <nico@cryptonector.com>
wrote:

> With existing APIs, dealing with "pools of meaningfully distinct
> tickets" seems meaningfully non-trivial.
>

I would actually prefer if the client could request N tickets, but was
advised that this was too large a change to the protocol.

> > There's also an observation there that it should really be that
> > > clients "MUST" use tickets only once. Any re-use likely discloses
> > > the obfuscated ticket age, which is intended to be secret. Right now
> > > it's a "SHOULD".
>
> Why should ticket age disclosure be a problem?  How does ticket one-time
> use not do the same?
>

The draft writes that it is to prevent connection correlation attacks.

-- 
Colm

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