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Re: [apps-discuss] HTTP MAC Authentication Scheme

From: Mark Nottingham <mnot@mnot.net>
Date: Thu, 2 Jun 2011 10:15:37 +1000
Cc: "apps-discuss@ietf.org" <apps-discuss@ietf.org>, Ben Adida <ben@adida.net>, "http-state@ietf.org" <http-state@ietf.org>, OAuth WG <oauth@ietf.org>, "'Adam Barth (adam@adambarth.com)'" <adam@adambarth.com>, HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <BB837BE0-060E-4201-821A-4A7F5FFED3A4@mnot.net>
To: Eran Hammer-Lahav <eran@hueniverse.com>

On 02/06/2011, at 1:00 AM, Eran Hammer-Lahav wrote:

> This was suggested before, but are there really attack vectors for this?

If not having a current, working attack to demonstrate is a valid way to shrug off a security concern, that's great; it'll be a useful approach to many of the discussions I have. :)


> The problem is that content-type is a pretty flexible header, which means normalization of the header will be required (case, parameter order, white space, etc.).

The media type is the important part, and it's much more constrained.


> I would argue that if you are using MAC with body hash and an attacker changing the media type can cause harm, you should use additional methods to secure the content-type (such as making the body self-describing).


That seems like a step backwards, considering all of the work that Adam has put into limiting the use of sniffing.

Cheers,

--
Mark Nottingham   http://www.mnot.net/
Received on Thursday, 2 June 2011 00:16:09 GMT

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