Re: [AVTCORE] Kathleen Moriarty's No Objection on draft-ietf-avtcore-aria-srtp-10: (with COMMENT)

Ben Campbell <ben@nostrum.com> Thu, 03 August 2017 13:55 UTC

Return-Path: <ben@nostrum.com>
X-Original-To: avt@ietfa.amsl.com
Delivered-To: avt@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 45C44132027; Thu, 3 Aug 2017 06:55:54 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.881
X-Spam-Level:
X-Spam-Status: No, score=-1.881 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RP_MATCHES_RCVD=-0.001, T_SPF_HELO_PERMERROR=0.01, T_SPF_PERMERROR=0.01] 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 kGJK_vVFpC86; Thu, 3 Aug 2017 06:55:52 -0700 (PDT)
Received: from nostrum.com (raven-v6.nostrum.com [IPv6:2001:470:d:1130::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id ABD50132043; Thu, 3 Aug 2017 06:55:52 -0700 (PDT)
Received: from [10.0.1.63] (cpe-66-25-7-22.tx.res.rr.com [66.25.7.22]) (authenticated bits=0) by nostrum.com (8.15.2/8.15.2) with ESMTPSA id v73DtfMj072515 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Thu, 3 Aug 2017 08:55:42 -0500 (CDT) (envelope-from ben@nostrum.com)
X-Authentication-Warning: raven.nostrum.com: Host cpe-66-25-7-22.tx.res.rr.com [66.25.7.22] claimed to be [10.0.1.63]
Content-Type: text/plain; charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\))
From: Ben Campbell <ben@nostrum.com>
In-Reply-To: <CAHbuEH6JJNq9QmAi9Dbg15-SctUS+c6FArW94KqfRzVP_g4gGw@mail.gmail.com>
Date: Thu, 3 Aug 2017 08:55:42 -0500
Cc: The IESG <iesg@ietf.org>, avtcore-chairs@ietf.org, Roni Even <roni.even@huawei.com>, draft-ietf-avtcore-aria-srtp@ietf.org, avt@ietf.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <D2164284-D756-4193-AF5E-258FF8EFC09B@nostrum.com>
References: <150172505031.5791.14553211399724965332.idtracker@ietfa.amsl.com> <084BEE4A-1241-42C6-BD39-36F11792ABB4@nostrum.com> <CAHbuEH4+R8KguTtLdoGnGdom1YB6Cp0XD5nLTm-YUMHaLsXxuw@mail.gmail.com> <D666082B-4DBF-406E-AC6C-03493A376A53@nostrum.com> <CAHbuEH6JJNq9QmAi9Dbg15-SctUS+c6FArW94KqfRzVP_g4gGw@mail.gmail.com>
To: Kathleen Moriarty <kathleen.moriarty.ietf@gmail.com>
X-Mailer: Apple Mail (2.3273)
Archived-At: <https://mailarchive.ietf.org/arch/msg/avt/mgUNq3oLeNETuHzFGLz4zc-XBEY>
Subject: Re: [AVTCORE] Kathleen Moriarty's No Objection on draft-ietf-avtcore-aria-srtp-10: (with COMMENT)
X-BeenThere: avt@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Audio/Video Transport Core Maintenance <avt.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/avt>, <mailto:avt-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/avt/>
List-Post: <mailto:avt@ietf.org>
List-Help: <mailto:avt-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/avt>, <mailto:avt-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 03 Aug 2017 13:55:54 -0000

> On Aug 3, 2017, at 8:26 AM, Kathleen Moriarty <kathleen.moriarty.ietf@gmail.com> wrote:
> 
> Hi Ben,
> 
> On Wed, Aug 2, 2017 at 11:15 PM, Ben Campbell <ben@nostrum.com> wrote:
>> 
>>> On Aug 2, 2017, at 9:50 PM, Kathleen Moriarty <kathleen.moriarty.ietf@gmail.com> wrote:
>>> 
>>> Hi Ben,
>>> 
>>> Thanks for the quick response, inline.
>>> 
>>> On Wed, Aug 2, 2017 at 10:36 PM, Ben Campbell <ben@nostrum.com> wrote:
>>>> 
>>>> 
>>>> 
>>>>> On Aug 2, 2017, at 8:50 PM, Kathleen Moriarty <kathleen.moriarty.ietf@gmail.com> wrote:
>>>>> ----------------------------------------------------------------------
>>>>> COMMENT:
>>>>> ----------------------------------------------------------------------
>>>>> 
>>>>> Although this is not a discuss, I think updated text would be very helpful on
>>>>> the following two issues.
>>>>> 
>>>>> I agree with the SecDir reviewer that there should be more text around the
>>>>> short tag length in the security considerations section.  I don't see a
>>>>> response to that post though.
>>>>> 
>>>> 
>>>> Hi Kathleen,
>>>> 
>>>> I think you are referring to Ben Laurie’s SecDir review of 06, rather than his later review of 09. Is that correct? Version 9 removed the GCM_8 modes. Or were you referring to something else?
>>> 
>>> I am referring to Ben's review of -06, where he had the following text:
>>> 
>>> Thirdly, I am not familiar enough with SRTP to understand why short
>>> authentication tags are needed, but in general its a bad idea, so I
>>> feel the Security Considerations should explain more fully than
>>> "Ciphersuites with short tag length may be
>>>  considered for specific application environments stated in 7.5 of
>>>  [RFC3711], but the risk of weak authentication described in
>>>  Section 9.5.1 of [RFC3711] should be taken into account."
>>> 
>>> I don't see an update to this text to address his question - providing
>>> additional information as to what should be "taken into account”.
>> 
>> I had assumed his concern was about short tags in GCM mode, namely the following:
>> 
>>       AEAD_ARIA_128_GCM_8
>>       AEAD_ARIA_256_GCM_8
>>       AEAD_ARIA_128_GCM_12
>>       AEAD_ARIA_256_GCM_12
>> 
>> These have all been removed as of version 09. Ben’s review of 09 made no further mention of short tags.
> 
> Thanks, but the text warning about them remains in the security
> considerations section.  Is it needed for some reason?
> 

Ah, I get it—I thought you were asking for _more_ text :-). I think they put that in as a result of the 06 review, but didn’t take it out when they removed those modes. I will verify that the authors don’t think the warning applies to any of the remaining.

Ben.

> Kathleen
> 
>> 
>> Are there suites still in version 09 that you think need further discussion in the security considerations?  I think the authors would happily add something if we can tell them what is needed, but I’m certainly not the expert here.
>> 
>> Ben.
>> 
> 
> 
> 
> -- 
> 
> Best regards,
> Kathleen