Re: [TLS] Zero-RTT Data & PSK

Eric Rescorla <ekr@rtfm.com> Mon, 10 October 2016 22:00 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Mon, 10 Oct 2016 14:59:17 -0700
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To: Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: [TLS] Zero-RTT Data & PSK
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I agree with MT. Hannes, if you want to clean up the text to take into
account MT's comments, I will merge

On Sat, Sep 10, 2016 at 3:35 AM, Martin Thomson <martin.thomson@gmail.com>;
wrote:

> On 9 September 2016 at 23:37, Hannes Tschofenig
> <hannes.tschofenig@gmx.net>; wrote:
> > I am wondering why I cannot use Zero-RTT with just PSK-based
> authentication
> > (without a prior ticket change).
>
> I think that you would need to bind more things to the key in that
> case, but I assume that it would be OK if you did so.  You already
> need to pair a PSK with a hash, but if you paired it with a whole
> cipher suite instead and also the ALPN (which could be null), then I
> see no reason not to permit 0-RTT for pure PSK.  (I think that cipher
> suite + ALPN is sufficient, but someone can correct me if I missed
> anything.)
>
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