Re: [TLS] Working Group Last Call for draft-ietf-tls-tls13-18

mrex@sap.com (Martin Rex) Wed, 09 November 2016 17:42 UTC

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In-Reply-To: <87inrweg88.fsf@alice.fifthhorseman.net>
To: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
Date: Wed, 9 Nov 2016 18:42:19 +0100 (CET)
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From: mrex@sap.com (Martin Rex)
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Subject: Re: [TLS] Working Group Last Call for draft-ietf-tls-tls13-18
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Daniel Kahn Gillmor wrote:
>
> Martin Rex wrote:
>>
>> The problem here is that this breaks (network) flow control, existing
>> (network socket) event management, and direction-independent connection
>> closure, and does so completely without value.
> 
> Martin, you keep saying things like "without value", while other people
> on this thread (Rich, Ilari, Yoav) have given you examples of the value
> it provides.  You don't seem to be trying to understand those positions.

Nobody so far has provide a single example of *REAL* value.
For the hiding of ContentType to provide real value, the prerequisites are:

  (1) this value will be _unconditionally_ provided in TLSv1.3

  (2) this value can be demonstrated to be a real security issue in TLSv1.2,
      for existing usage scenarios, where hiding of ContentType is not
      available

Anyhing less is no value, just an illusion of value.


> 
> This WG isn't chartered to defend the engineering optimizations made by
> any particular middlebox vendor.  It's chartered to improve the privacy
> and security guarantees offered to users of TLS.

You are confusing _middlebox_ with _middleware_at_the_endpoint_,
which is a huge difference, because the middleboxes are performing
man-in-the-middle attacks, whereas the _middleware_at_the_endpoint_
has regular access to the entire plaintext of the communication.

The problem with hiding of TLS record ContentTypes is that it severely
interferes with efficient streaming network I/O--which is preferably
performed outside/above the TLS implementation and async non-blocking
whenever you get into thousands of parallel connections.


-Martin