Re: Comments on Explicit/Trusted Proxy

Werner Baumann <werner.baumann@onlinehome.de> Sun, 05 May 2013 08:43 UTC

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Date: Sun, 5 May 2013 10:39:33 +0200
From: Werner Baumann <werner.baumann@onlinehome.de>
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Subject: Re: Comments on Explicit/Trusted Proxy
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Am Sat, 04 May 2013 19:34:57 +0100
schrieb Stephen Farrell <stephen.farrell@cs.tcd.ie>;:

> No, I'm not insulting anyone nor trying to. I am describing
> the purported requirements here as mainly-bogus which is
> pejorative but entirely different and is IMO justified. I
> think emphasis on the bogosity of the purported requirements
> is deserved.
> ...
> - Possible government mandated MITM attacks on IETF protocols
> were a major factor in why we ended up with RFC2804. I suggest
> that's required reading for people proposing work on this
> topic.

Definition of Wiretapping from RFC2804:

   Wiretapping is what occurs when information passed across the
   Internet from one party to one or more other parties is delivered to
   a third party:

   1. Without the sending party knowing about the third party

   2. Without any of the recipient parties knowing about the delivery to
      the third party

   3. When the normal expectation of the sender is that the transmitted
      information will only be seen by the recipient parties or parties
      obliged to keep the information in confidence

   4. When the third party acts deliberately to target the transmission
      of the first party, either because he is of interest, or because
      the second party's reception is of interest.

An explicit trusted proxy does not meet this definition of wiretapping
because of condition 1. Whether information is delivered to a third
party at all depends on the administration of that proxy. End users will
have to decide whether to trust it or not (which is much more easy done
than to decide whether to trust some CA or not).

All participants in this discussion that argued in favor of explicit
trusted proxies did it to stop a situation where this is done without
the end user knowing of the interception. The whole point of these
proposals is to make the user aware of the proxy and to allow the user
to either agree or deny.

Start of not trying to insult section:
Repeating the mantra "Don't open TLS to MITM attacks" is bogus in face
of the well known fact that TLS is susceptible to MITM attacks
(mostly due to not trustworthy CAs) and that this weakness is already
widely exploited.

Werner