Re: [Secdispatch] EDHOC Summary

Benjamin Kaduk <kaduk@mit.edu> Fri, 19 April 2019 05:23 UTC

Return-Path: <kaduk@mit.edu>
X-Original-To: secdispatch@ietfa.amsl.com
Delivered-To: secdispatch@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id B51AB120072 for <secdispatch@ietfa.amsl.com>; Thu, 18 Apr 2019 22:23:30 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.6
X-Spam-Level:
X-Spam-Status: No, score=-2.6 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Er3vySPpS2we for <secdispatch@ietfa.amsl.com>; Thu, 18 Apr 2019 22:23:28 -0700 (PDT)
Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 7FD32120020 for <secdispatch@ietf.org>; Thu, 18 Apr 2019 22:23:28 -0700 (PDT)
Received: from kduck.mit.edu (24-107-191-124.dhcp.stls.mo.charter.com [24.107.191.124]) (authenticated bits=56) (User authenticated as kaduk@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x3J5NOgr012215 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 19 Apr 2019 01:23:26 -0400
Date: Fri, 19 Apr 2019 00:23:24 -0500
From: Benjamin Kaduk <kaduk@mit.edu>
To: "Blomqvist, Peter" <Peter.Blomqvist@sony.com>
Cc: Richard Barnes <rlb@ipv.sx>, "secdispatch@ietf.org" <secdispatch@ietf.org>
Message-ID: <20190419052324.GB51586@kduck.mit.edu>
References: <d741d224c8324c3f8a300c467a836913@seldmbx10.corpusers.net> <CAL02cgSabY44iWzMzSo3SYtkC_nYc4h4sL5wA==VJQkgPar75A@mail.gmail.com> <1554794627589.50834@sony.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1554794627589.50834@sony.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Archived-At: <https://mailarchive.ietf.org/arch/msg/secdispatch/Ui_6VwwzACYwafi2Y2DKpBZ8SEM>
Subject: Re: [Secdispatch] EDHOC Summary
X-BeenThere: secdispatch@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Security Dispatch <secdispatch.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/secdispatch>, <mailto:secdispatch-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/secdispatch/>
List-Post: <mailto:secdispatch@ietf.org>
List-Help: <mailto:secdispatch-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/secdispatch>, <mailto:secdispatch-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 19 Apr 2019 05:23:31 -0000

On Tue, Apr 09, 2019 at 07:23:47AM +0000, Blomqvist, Peter wrote:
> Hi Richard,
> 
> 
> Code footprint is not extremely constrained, typically Cortex M4 or similar.
> 
> Battery however is constrained. Also data transport.
> 
> 
> Optimistic marketing state that devices now can run 10 years on coin cells - adding security to such a battery budget is problematic to say the least.

At one point I looked at the numbers in
https://datatracker.ietf.org/meeting/interim-2019-secdispatch-01/materials/slides-interim-2019-secdispatch-01-sessa-edhoc.pdf
and tried to do some ballpark numbers on total power consumption for key
exchange over the lifetime of the device.  I don't have a great handle on
whether, say, 1000 mAh is plausible for the usable energy in a coin cell,
but IIRC at one rekeying event per month and some similar assumptions I
could get the lifetime energy consumption to be around 0.5% for the AKE.
Hopefully someone could replicate those numbers (I don't remember where I
put my notes) and comment on how much slack there is in the power budget
for this sort of thing.

-Ben