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Re: [TLS] 0-RTT, server Application Data, and client Finished

David Benjamin <davidben@chromium.org> Wed, 27 January 2016 19:28 UTC

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From: David Benjamin <davidben@chromium.org>
Date: Wed, 27 Jan 2016 19:28:47 +0000
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To: Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: [TLS] 0-RTT, server Application Data, and client Finished
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On Tue, Jan 26, 2016 at 10:32 PM Martin Thomson <martin.thomson@gmail.com>
wrote:

> On 27 January 2016 at 14:11, David Benjamin <davidben@chromium.org> wrote:
> > Why do you say it's an optimization? They're exactly the same except the
> > simplified one reduces to normal 0-RTT + mid-stream CertificateRequest (a
> > combination that's possible with or without my restriction) and the
> other is
> > a brand new handshake flow to worry about.
>
> I get your point, but I don't see that as a simplification.  In my
> mind, post-handshake client authentication doesn't happen.  Or, I
> don't see it being commonplace.
>

I certainly hope it doesn't become commonplace either! :-)

But the only cases where this flow is useful (server sends non-zero
unauthenticated bytes at t=0.5 before the authenticated bytes at t=1.5) has
all the same pitfalls of mid-stream auth (specifically that the stream's
authentication switches partway through), so I don't see what avoiding
mid-stream auth is supposed to gain.

David

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