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Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00

Florian Weimer <fw@deneb.enyo.de> Wed, 29 October 2014 11:27 UTC

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From: Florian Weimer <fw@deneb.enyo.de>
To: "tls@ietf.org" <tls@ietf.org>
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Date: Wed, 29 Oct 2014 12:27:00 +0100
In-Reply-To: <CADMpkcLLOrUQMxbeCW7RB+Gf12Ux_wK_eotKdbH0RMpeuaptfQ@mail.gmail.com> (Bodo Moeller's message of "Wed, 29 Oct 2014 10:55:58 +0100")
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Subject: Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00
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* Bodo Moeller:

> I think you have mentioned that issue before, but I must admit that I am
> not sure I understand what your concern is. If you are referring to
> https://bugzilla.mozilla.org/show_bug.cgi?id=1072382, that's a bug that was
> found and fixed *because* TLS_FALLBACK_SCSV was rolled out. How, then, is
> this an argument *against* TLS_FALLBACK_SCSV semantics?

This bug in the fallback logic was actually reported in 2008:

  <https://bugzilla.mozilla.org/show_bug.cgi?id=450280>

My concern is that this bug has tainted the telemetry data collected
by Mozilla, and may have grossly exaggerated the need for fallback.
And as far as I can tell, the patch for bug 1072382 only makes the
fallback less sticky, it still does not result in better reporting of
fallbacks in telemetry data.

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