Re: [TLS] Finished stuffing/PSK Binders

Benjamin Kaduk <bkaduk@akamai.com> Wed, 12 October 2016 15:14 UTC

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To: Ilari Liusvaara <ilariliusvaara@welho.com>, Martin Thomson <martin.thomson@gmail.com>
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From: Benjamin Kaduk <bkaduk@akamai.com>
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Date: Wed, 12 Oct 2016 10:13:57 -0500
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Subject: Re: [TLS] Finished stuffing/PSK Binders
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On 10/12/2016 09:27 AM, Ilari Liusvaara wrote:
> On Wed, Oct 12, 2016 at 09:43:05PM +1100, Martin Thomson wrote:
>> On 12 October 2016 at 19:50, Ilari Liusvaara <ilariliusvaara@welho.com>; wrote:
>>
>> Maybe we should require text for every extension that can appear in
>> the HRR: what to do if the extension is in the HRR, and what to do if
>> it isn't.
> Or have every extension be "no change" if not present, and do the
> specified thing to CH if prsent and known, abort if present and
> unknown.

This is an instance of the "require text for every extension" case,
though I think either would work.

> That would waste a bit of space with extensions signaling support
> for some rewrites if the server doesn't use those but retries the
> handshake.
>

I'm having trouble parsing this.  The idea is that the client would
waste some space in the new CH because the server doesn't have a way to
indicate that the client only needs to send a subset of what it sent the
first time around?

-Ben