IETF Logo Mail Archive

Re: [IPsec] AES key lengths: draft-ietf-ipsecme-esp-ah-reqts

Stephen Kent <kent@bbn.com> Mon, 10 March 2014 16:05 UTC

Return-Path: <kent@bbn.com>
X-Original-To: ipsec@ietfa.amsl.com
Delivered-To: ipsec@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 272491A04C5 for <ipsec@ietfa.amsl.com>; Mon, 10 Mar 2014 09:05:40 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.748
X-Spam-Level:
X-Spam-Status: No, score=-4.748 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RP_MATCHES_RCVD=-0.547, SPF_PASS=-0.001] autolearn=ham
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 Z4mUnQ5gGSHq for <ipsec@ietfa.amsl.com>; Mon, 10 Mar 2014 09:05:31 -0700 (PDT)
Received: from smtp.bbn.com (smtp.bbn.com [128.33.0.80]) by ietfa.amsl.com (Postfix) with ESMTP id 994821A04E8 for <ipsec@ietf.org>; Mon, 10 Mar 2014 09:05:28 -0700 (PDT)
Received: from dommiel.bbn.com ([192.1.122.15]:41210 helo=comsec.home) by smtp.bbn.com with esmtp (Exim 4.77 (FreeBSD)) (envelope-from <kent@bbn.com>) id 1WN2he-0000xY-Mp for ipsec@ietf.org; Mon, 10 Mar 2014 12:05:22 -0400
Message-ID: <531DE2C2.7050109@bbn.com>
Date: Mon, 10 Mar 2014 12:05:22 -0400
From: Stephen Kent <kent@bbn.com>
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:24.0) Gecko/20100101 Thunderbird/24.3.0
MIME-Version: 1.0
To: ipsec@ietf.org
References: <8D3D17ACE214DC429325B2B98F3AE71206CF439362@MX15A.corp.emc.com> <C75A84166056C94F84D238A44AF9F6AD06F1684B@AUSX10MPC102.AMER.DELL.COM>
In-Reply-To: <C75A84166056C94F84D238A44AF9F6AD06F1684B@AUSX10MPC102.AMER.DELL.COM>
Content-Type: text/plain; charset="windows-1252"; format="flowed"
Content-Transfer-Encoding: 8bit
Archived-At: http://mailarchive.ietf.org/arch/msg/ipsec/q65zE_wXMXv5BbnNbFo17lzM1MU
Subject: Re: [IPsec] AES key lengths: draft-ietf-ipsecme-esp-ah-reqts
X-BeenThere: ipsec@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Discussion of IPsec protocols <ipsec.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ipsec>, <mailto:ipsec-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/ipsec/>
List-Post: <mailto:ipsec@ietf.org>
List-Help: <mailto:ipsec-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ipsec>, <mailto:ipsec-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 10 Mar 2014 16:05:41 -0000

Paul
> On Mar 8, 2014, at 8:08 AM, Black, David <david.black@emc.com> wrote:
>
>>> The next draft changes AES-128-CBC to AES-CBC, and says:
>>>
>>> In the following sections, all AES modes are for 128-bit AES. 192-bit AES
>>> MAY be supported for those modes, but the requirements here are for 128-bit
>>> AES.
>> What about 256-bit AES keys?  They should also be a "MAY".
> Why not “SHOULD” for 192 and 256 bit keys?
>
> 	paul
It's good to remember the reason that 256-bits keys for AES were specified,
i.e., as a hedge against someone building a quantum computer. So, unless the
data being encrypted is expected to have a lifetime far enough into the 
future
as to merit protection against that concern, the extra time needed to 
perform
AES-256 vs. AES-128 does not seem justified.

Steve

v2.23.0 | Report a Bug | By Email