Re: [rtcweb] Security Architecture -07 review

Dan Wing <dwing@cisco.com> Fri, 26 July 2013 00:00 UTC

Return-Path: <dwing@cisco.com>
X-Original-To: rtcweb@ietfa.amsl.com
Delivered-To: rtcweb@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2842021F8F29 for <rtcweb@ietfa.amsl.com>; Thu, 25 Jul 2013 17:00:55 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -110.599
X-Spam-Level:
X-Spam-Status: No, score=-110.599 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, RCVD_IN_DNSWL_HI=-8, USER_IN_WHITELIST=-100]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 0-Bvb9yoBYqT for <rtcweb@ietfa.amsl.com>; Thu, 25 Jul 2013 17:00:49 -0700 (PDT)
Received: from mtv-iport-4.cisco.com (mtv-iport-4.cisco.com [173.36.130.15]) by ietfa.amsl.com (Postfix) with ESMTP id DC61321F84BB for <rtcweb@ietf.org>; Thu, 25 Jul 2013 17:00:49 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=923; q=dns/txt; s=iport; t=1374796850; x=1376006450; h=mime-version:subject:from:in-reply-to:date:cc: content-transfer-encoding:message-id:references:to; bh=FsmQUznaHtewGcsZFmlGlSPGbYa+qUR4Ix8toHebIKc=; b=ExsLQBxeA9IVy9UfJyBz0scHwMOqveGG+NeipURmbuo9dzedyG9LlQen NVBZ04iEIt6rlem+Dg3lQHJNlzzcl3wW5TwFqbEefHTIV9nCwP+23IF/W 0prRrRZVy2IPJha0OzY5dlwT56UAD7jG1Qsi4542y/EYh9WAzRDdBKa2M s=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AhYFAN268VGrRDoH/2dsb2JhbABagwaDSrsfgRQWdIIkAQEBAwE6PwULCxIGLiEoDgYTh34DCQWwKg2IXo0VgjUzB4MSbgOJKoxMgWmMJ4UmgzQc
X-IronPort-AV: E=Sophos;i="4.89,746,1367971200"; d="scan'208";a="87235063"
Received: from mtv-core-2.cisco.com ([171.68.58.7]) by mtv-iport-4.cisco.com with ESMTP; 26 Jul 2013 00:00:49 +0000
Received: from sjc-vpn7-2043.cisco.com (sjc-vpn7-2043.cisco.com [10.21.151.251]) by mtv-core-2.cisco.com (8.14.5/8.14.5) with ESMTP id r6Q00mF3002452; Fri, 26 Jul 2013 00:00:48 GMT
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 6.5 \(1508\))
From: Dan Wing <dwing@cisco.com>
In-Reply-To: <CABkgnnW71aGwgaX3oBYofQaHP7pFyyh9mGifXdFL=NYiJ+qfYw@mail.gmail.com>
Date: Thu, 25 Jul 2013 17:00:48 -0700
Content-Transfer-Encoding: quoted-printable
Message-Id: <3F737E1C-BBF9-4399-8B7D-B50FB4A2FFC0@cisco.com>
References: <CABkgnnWUZXBRneGnRsA9Xo-rrdw7nAsBR+5SL6SRyjbR+Egfgw@mail.gmail.com> <D96D0971-E3A7-4E96-B3F4-83C2044252B7@cisco.com> <CABkgnnW71aGwgaX3oBYofQaHP7pFyyh9mGifXdFL=NYiJ+qfYw@mail.gmail.com>
To: Martin Thomson <martin.thomson@gmail.com>
X-Mailer: Apple Mail (2.1508)
Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Security Architecture -07 review
X-BeenThere: rtcweb@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <rtcweb.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/rtcweb>
List-Post: <mailto:rtcweb@ietf.org>
List-Help: <mailto:rtcweb-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 26 Jul 2013 00:00:55 -0000

On Jul 25, 2013, at 4:12 PM, Martin Thomson <martin.thomson@gmail.com> wrote:

> On 25 July 2013 14:54, Dan Wing <dwing@cisco.com> wrote:
>>> However, the cookie issue is still a problem.  Removing the
>>> certificate and key pair when cookies are cleared is necessary.
>> 
>> Wrapping the DTLS handshake inside a DH exchange would achieve both goals (preventing a super-cookie from being passively observed, as well as giving key continuity).
> 
> For passive observers, yes, but I'm not that concerned about them.
> After all, they are seeing the flow, so can make all sorts of
> inferences based on the flow addressing.

But that doesn't mean we should purposefully leak even more information at another layer.

> The concern is the first party, who gets the certificate.  Using DH
> isn't going to fix that.

Then you're arguing for "endpoint MUST NOT change its certificate".

-d