[websec] [HSTS] Contradiction between sections 8.1 and 11.3 of RFC 6797?

Stephane Bortzmeyer <bortzmeyer@nic.fr> Wed, 17 December 2014 13:57 UTC

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Date: Wed, 17 Dec 2014 14:56:59 +0100
From: Stephane Bortzmeyer <bortzmeyer@nic.fr>
To: websec@ietf.org, Jeff.Hodges@PayPal.com, collin.jackson@sv.cmu.edu, ietf@adambarth.com
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Subject: [websec] [HSTS] Contradiction between sections 8.1 and 11.3 of RFC 6797?
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[I'm not subscribed to the websec working group so please copy me when

I don't know how to read section 11.3 of RFC 6797. It says "If all
four of the following conditions are true... [self-signed
certificates...]  ...then secure connections to that site will fail,
per the HSTS design." It seems to imply that adding a
Strict-Transport-Security: header to a site which has a self-signed
certificate is an error.

But section 8.1 says that the Strict-Transport-Security: will be
ignored if the HTTPS session is not secured (for instance because the
client uses a self-signed cert, section 8.1 says the header will be
accepted only "if there are no underlying secure transport errors or
warnings"). So, it seems that adding Strict-Transport-Security: is
useless (they will be ignored, per section 8.1) but not an error.

I checked with the Chromium browser "Version 20.0.1132.47 Ubuntu 12.04
(144678)" and a HTTPS site signed by CAcert.org (unknown CA for most
browsers) and, indeed, Chromium ignores the HSTS header and accepts to
use HTTP. Once CAcert.org cert is added, Chromium accepts the HSTS
header and uses only HTTPS. So, it seems the Chromium programmers
decided to ignore section 11.3?