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

Bill Cox <waywardgeek@google.com> Wed, 27 January 2016 16:13 UTC

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Date: Wed, 27 Jan 2016 08:13:11 -0800
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From: Bill Cox <waywardgeek@google.com>
To: Watson Ladd <watsonbladd@gmail.com>
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Subject: Re: [TLS] 0-RTT, server Application Data, and client Finished
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On Wed, Jan 27, 2016 at 7:09 AM, Watson Ladd <watsonbladd@gmail.com> wrote:

>
> All certificate based authentication over HTTP is currently done by
> renegotiation, when the client chooses to access a protected resource
> a Renegotiation Request is sent, leading to the client certificate
> being provided in the second handshake. It's true that FIDO will be a
> better solution (currently unfinished), but when changing TLS stacks
> to work with TLS 1.3 we need to support this case, without requiring
> changes to application code below this.
>

Thanks for the explanation.  That makes sense.

>
> All 0-RTT data is replayable, but I don't see what replaying a
> authenticated replayable connection gets you.
>

I do not either.  However, a 0-RTT CertificateVerify from the client is not
as secure as a regular CertificateVerify.  I doubt anyone has a use case
for it in the near-term, and with FIDO coming in the future, I would
recommend removing it from the 0-RTT first-flight diagram.

There, did I actually suggest something useful for TLS 1.3?  It will make
my day if so... :)

Bill

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