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Re: [TLS] Cleaning up 0-RTT Signaling (ciphersuites, replays, PSK context)

Colm MacCárthaigh <colm@allcosts.net> Fri, 25 March 2016 19:41 UTC

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Date: Fri, 25 Mar 2016 12:41:04 -0700
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From: Colm MacCárthaigh <colm@allcosts.net>
To: Karthik Bhargavan <karthikeyan.bhargavan@inria.fr>
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Subject: Re: [TLS] Cleaning up 0-RTT Signaling (ciphersuites, replays, PSK context)
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On Fri, Mar 25, 2016 at 12:02 PM, Karthik Bhargavan <
karthikeyan.bhargavan@inria.fr> wrote:

> > +1 but I think we can go further here and specify 0RTT in such a way
> that it only works when the server maintains state, and so that any given
> 0RTT ticket may only be used once (to preserve forward secrecy as much as
> possible within the constrains of 0RTT).
>
> Do you envision clients only having one resumption handshake at a time? I
> was under the impression that TLS 1.2 clients typically open multiple
> resumption handshakes in parallel, and that TLS 1.3 clients would want to
> do the same.
>

It is common for existing clients to re-use the same ticket for many
connections. This is at-odds with forward secrecy though :/ Clients could
have many resumption tokens at a time though; e.g. they could ask for 10
and use each one once. It's just that each token is used once. So parallel
resumptions could be supported.


-- 
Colm

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