Re: [secdir] SecDir review of draft-ietf-mpls-ldp-hello-crypto-auth-05

Stephen Farrell <stephen.farrell@cs.tcd.ie> Wed, 21 May 2014 12:58 UTC

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Date: Wed, 21 May 2014 13:57:54 +0100
From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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To: "Bhatia, Manav (Manav)" <manav.bhatia@alcatel-lucent.com>, Loa Andersson <loa@pi.nu>, Manav Bhatia <manavbhatia@gmail.com>
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Subject: Re: [secdir] SecDir review of draft-ietf-mpls-ldp-hello-crypto-auth-05
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On 21/05/14 12:14, Bhatia, Manav (Manav) wrote:
> I agree with Loa.
> 
> Our current draft is very simple and has gone through multiple
> iterations of reviews in at least two WGs. It brings LDP to the same
> level of security as other protocols running in the networks.

Fully agree with that goal.

> 
> I think we should just push it forward and if there is an interest in
> writing a new ID that updates HMAC specification, then we write one
> that includes the Apad stuff. I think the latter should anyways be
> done, regardless of what happens to this particular draft.

I need to read it. But I'd be happier if that HMAC draft existed
and was going to be processed - then we wouldn't have to do this
discussion again.

Cheers,
S.

> 
> The IETF submission site is down and hence couldn’t upload the
> revised ID (addressing Yaron's comments). Will do it tomorrow once
> its up.
> 
> After that its ready to be placed before the IESG.
> 
> Cheers, Manav
> 
>> -----Original Message----- From: Loa Andersson [mailto:loa@pi.nu] 
>> Sent: Wednesday, May 21, 2014 4:29 PM To: Manav Bhatia; Stephen
>> Farrell Cc: Bhatia, Manav (Manav); IETF Security Directorate; The
>> IESG; draft- ietf-mpls-ldp-hello-crypto-auth.all@tools.ietf.org;
>> Yaron Sheffer Subject: Re: SecDir review of
>> draft-ietf-mpls-ldp-hello-crypto-auth-05
>> 
>> Folks,
>> 
>> I'm only the document shepherd. My feeling is that we are raising 
>> the hurdle step by step for the KARP - initiated RFCs, the first 
>> was comparatively smooth, now we are trying to put an 18 months 
>> effort (individual draft to RFC) in front of approving something 
>> that is comparatively simple and seen as raising LDP to the same 
>> security as the other routing protocols.
>> 
>> So if we get to tired to push this, we are all better off not
>> doing the security work for this particular protocol?
>> 
>> Someone said - "Never let the best be the enemy of the possible"!
>> 
>> /Loa
>> 
>> 
>> 
>> On 2014-05-21 12:39, Manav Bhatia wrote:
>>> Stephen,
>>> 
>>>>> This however is a long drawn discussion because everyone
>>>>> needs to
>> be
>>>>> convinced on the merits of updating the HMAC specification --
>>>>> which
>> I
>>>>> am not sure will take how long.
>>>> 
>>>> So I need to look at this draft, HMAC and the other cases but 
>>>> it seems to me that you're copying a page or two of crypto spec
>>>> each time and changing one line. Doing that over and over is a
>>>> recipe for long term pain, isn't it?
>>> 
>>> It sure is.
>>> 
>>> I had volunteered to write a 1-2 page long ID that updated the
>>> HMAC
>> to
>>> include the Apad, but the idea was shot down. The only
>>> alternative left was to include the crypto stuff in each standard
>>> that we wrote later.
>>> 
>>>> 
>>>> (And we've had this discussion for each such draft while I've 
>>>> been on the IESG I think, which is also somewhat drawn out;-)
>>> 
>>> This draft is probably the last one thats coming from the Routing
>>> WG which will have this level of crypto mathematics spelled out.
>>> All other IGPs are already covered. In case we need to change
>>> something
>> in
>>> the ones already covered we can refer to the base RFC where we
>>> have detailed the crypto maths. For example, 
>>> draft-ietf-ospf-security-extension-manual-keying-08 amongst
>>> other things also updates the definition of Apad. It points to
>>> the exact mathematics in RFC 5709 and only updates the Apad
>>> definition in that draft. This draft btw has cleared the WG LC
>>> and would be appearing before you guys very soon.
>>> 
>>> Given this, i think we should just pass this draft with this
>>> level of details. Subsequently, when LDP wants to update
>>> something, it can normatively refer to this RFC and only give the
>>> changes.
>>> 
>>> Cheers, Manav
>>> 
>>>> 
>>>> S.
>>>> 
>>>> 
>>>>> 
>>>>> Cheers, Manav
>>>>> 
>>>>> 
>>>>>> 
>>>>>> S
>>>>>> 
>>>>>>> 
>>>>>>> Cheers, Manav
>>>>>>> 
>>>>>>>> -----Original Message----- From: Stephen Farrell 
>>>>>>>> [mailto:stephen.farrell@cs.tcd.ie] Sent: Wednesday, May
>>>>>>>> 21, 2014 2:53 AM To: Bhatia, Manav (Manav); IETF
>>>>>>>> Security Directorate; The IESG; draft- 
>>>>>>>> ietf-mpls-ldp-hello-crypto-auth.all@tools.ietf.org Cc:
>>>>>>>> Yaron Sheffer; manavbhatia@gmail.com Subject: Re:
>>>>>>>> SecDir review of 
>>>>>>>> draft-ietf-mpls-ldp-hello-crypto-auth-05
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> On 19/05/14 21:27, Yaron Sheffer wrote:
>>>>>>>>>>> 
>>>>>>>>>>> * 5.1: Redefining HMAC (RFC 2104) is an extremely
>>>>>>>>>>> bad idea. This reviewer does not have the
>>>>>>>>>>> appropriate background to critique the proposed
>>>>>>>>>>> solution, but there must be an overwhelming
>>>>>>>>>>> reason to
>>>>>>>> reopen> >>>>> cryptographic primitives.
>>>>>>>>>> 
>>>>>>>>>> This is a decision that was taken by Sec Ads when
>>>>>>>>>> we were doing the crypto protection for the IGPs
>>>>>>>>>> based on some feedback from NIST.
>>>>>>>> This
>>>>>>>>>> mathematics is not new and has been done for all
>>>>>>>>>> IGPs and has been approved and rather encouraged by
>>>>>>>>>> the Security ADs.
>>>>>>>> 
>>>>>>>> The above does not sound like something I recognise. I
>>>>>>>> have repeatedly asked that documents not re-define
>>>>>>>> HMAC. Perhaps this time, I'll make that a DISCUSS and
>>>>>>>> not budge. I probably should have done that before
>>>>>>>> TBH.
>>>>>>>> 
>>>>>>>> If you are revising that doc, *please* get rid of the 
>>>>>>>> re-definition and just properly refer to HMAC. Its
>>>>>>>> about time to stop repeating that error.
>>>>>>>> 
>>>>>>>> S.
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>> 
>>>>> 
>>>>> 
>> 
>> --
>> 
>> 
>> Loa Andersson                        email: loa@mail01.huawei.com 
>> Senior MPLS Expert                          loa@pi.nu Huawei
>> Technologies (consultant)     phone: +46 739 81 21 64