Re: [IPsec] New PAKE Criteria draft posted (def. of gateway)

"Dan Harkins" <dharkins@lounge.org> Sun, 28 March 2010 00:39 UTC

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Date: Sat, 27 Mar 2010 17:39:30 -0700 (PDT)
From: "Dan Harkins" <dharkins@lounge.org>
To: "Yaron Sheffer" <yaronf.ietf@gmail.com>
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Cc: ipsec@ietf.org, Dan Harkins <dharkins@lounge.org>, Kaz Kobara <kobara_conf@m.aist.go.jp>
Subject: Re: [IPsec] New PAKE Criteria draft posted (def. of gateway)
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  Hi Yaron,

  Since you did not respond to my question, I guess I can infer then that
there is no protocol issue _right now_ that would prevent some password
authentication scheme from being used with a "client" and a "gateway".
That being the case, the criteria document should not constrain any
possible solution.

  The charter mentions these use cases because you have to justify _why_
you want to change the charter, what problem are you solving. Those
use cases were used to illustrate a problem to solve and justify why the
charter had to be changed. Just because you happen to solve problem A
with some protocol does not mean that the protocol must be prevented from
also solving problem B.

  If you want to use EAP then knock yourself out. If you're happy with
pointless encapsulation and more state machines and code you have to
implement then please have at it. But don't make a different protocol
hamstrung just because it might be used instead of EAP.

  There is no TECHNICAL reason to prevent a password authentication scheme
in IKE(v2) from being used between a "client" and a "gateway". Since we're
a working group that deals with technical issues we can therefore safely
dispense with any artificial constraints on our protocols.

  Dan.

On Sat, March 27, 2010 2:21 pm, Yaron Sheffer wrote:
> Hi Dan,
>
> Again, the criteria document is just following the charter in mentioning
> this constraint.
>
> The protocol we end up with might have all sorts of nice-to-have
> features and behaviors. But for the criteria, we have to focus on what's
> important. Use cases that were excluded in the charter (and for good
> reason, because we have a perfectly good solution for them today) do not
> fall into this category.
>
> Thanks,
> 	Yaron
>
> On 27.3.2010 22:15, Dan Harkins wrote:
>>
>>    Hi Yaron,
>>
>>    You say below, "If a protocol can be specified for the general use
>> case,
>> that's very well. But there will be protocols that are only applicable
>> to some specific use cases, and that's fine, too." But then the criteria
>> document says, "This document is limited to the use of password-based
>> authentication to achieve trust between gateways."
>>
>>    So basically the criteria document is specifying it for a particular
>> use only when there is no protocol issue that would prevent it from
>> being
>> used in the general case. It should be "very well" if it worked "for the
>> general use case" but the criteria draft is preventing it from doing so.
>>
>>    In RFC 2409 it was not possible to do the "remote access" thing with
>> a
>> PSK because protocol limitations forced the PSK to be bound to one IP
>> address. That's an example of a protocol limiting usage. But I don't see
>> that now. What could possibly limit what we're talking about _right now_
>> to some narrow uses? Maybe when we get around to designing the protocol
>> we'll run into something, and as you say "that's fine". But now, there
>> is
>> nothing to limit us and no reason to, a priori, say something is for
>> "gateways" only.
>>
>>    Of course, I could be wrong. So maybe you could explain why there is
>> some protocol issue that prevents using password-based authentication in
>> the general case.
>>
>>    Dan.
>>
>> On Sat, March 27, 2010 7:31 am, Yaron Sheffer wrote:
>>> Hi Dan,
>>>
>>> I'm afraid I disagree with you on several counts. See below.
>>>
>>> Thanks,
>>> 	Yaron
>>>
>>> On 26.3.2010 20:11, Dan Harkins wrote:
>>>>
>>>>     Telling administrators what they can and cannot do is really not
>>>> the function of our standards body. If someone wants to use a
>>>> "long secret" or a password to authenticate gateways, hosts, clients,
>>>> peers, or implementations (or whatever you want to call the box) it's
>>>> none of our business. We shouldn't say, "nope, sorry you can't do
>>>> that,
>>>> this is a client and you should use a stand-alone AAA server because
>>>> of
>>>> the obvious benefits that have eluded you."
>>>
>>> We cannot tell administrators anything for the simple reason that
>>> they're not looking to us for guidance. However we do have some
>>> influence over vendors, and we should tell vendors what we think makes
>>> sense, i.e. what is the architecturally correct way to use the
>>> protocol.
>>>
>>> More importantly, we should optimize the protocol (only) for the cases
>>> that we think are reasonable. So we should care very much about usage
>>> scenarios. As a concrete example, password management arguably matters
>>> much more to remote access than to gateway-to-gateway scenarios. Should
>>> we support it? Depends on the scenario(s) we want to work on.
>>>>
>>>>     We have RFCs on "host requirements" and "router requirements".
>>>> There
>>>> isn't an RFC on "peer requirements" or "client requirements". Those
>>>> are
>>>> terms that started in marketecture powerpoint slides and should not be
>>>> used to constrain or neuter our protocols.
>>> No. For years we've had specific IPsec work items on remote access,
>>> it's
>>> nothing new. If a protocol can be specified for the general use case,
>>> that's very well. But there will be protocols that are only applicable
>>> to some specific use cases, and that's fine, too.
>>>>
>>>>     Dan.
>>>>
>>>> On Fri, March 26, 2010 9:53 am, Kaz Kobara wrote:
>>>>> Hi Yaron
>>>>>
>>>>> Thank you for your clarification.
>>>>>
>>>>>> "between gateways" as opposed to
>>>>>> "between clients and gateways". So your assertion is correct.
>>>>>
>>>>> (Between gateways, administrators can set long secrets, so the
>>>>> necessity
>>>>> of
>>>>> PAKE seems smaller than between clients and gateways where passwords
>>>>> are
>>>>> recorded in the gateways and users have to type the passwords.)
>>>>>
>>>>> Anyway, if the scope is limited only on "between gateways" but not
>>>>> "between
>>>>> clients and gateways," the title
>>>>> "Password-Based Authentication in IKEv2: Selection Criteria and
>>>>> Comparison"
>>>>> seems misleading (since this itself misinforms that this criteria may
>>>>> be
>>>>> applied to IKEv2 in any cases), and the above should be clearly
>>>>> mentioned
>>>>> in
>>>>> the document.
>>>>>
>>>>> Kaz
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Yaron Sheffer [mailto:yaronf.ietf@gmail.com]
>>>>>> Sent: Friday, March 26, 2010 2:14 PM
>>>>>> To: Kaz Kobara
>>>>>> Cc: ipsec@ietf.org
>>>>>> Subject: Re: [IPsec] New PAKE Criteria draft posted (def. of
>>>>>> gateway)
>>>>>>
>>>>>> Hi Kaz,
>>>>>>
>>>>>> I *thought* my intention was clear: "between gateways" as opposed to
>>>>>> "between clients and gateways". So your assertion is correct.
>>>>>>
>>>>>> Thanks,
>>>>>> 	Yaron
>>>>>>
>>>>>> On 26.3.2010 1:40, Kaz Kobara wrote:
>>>>>>> Hi Yaron
>>>>>>>
>>>>>>>> draft-sheffer-ipsecme-pake-criteria-02.txt says in Page 4
>>>>>>>> "This document is limited to the use of password-based
>>>>>>>> authentication
>>>>>> to
>>>>>>>> achieve trust between gateways"
>>>>>>>
>>>>>>> I would like to make sure that
>>>>>>> "gateway" in this document does not encompass VPN clients and
>>>>>>> hosts,
>>>>> right?
>>>>>>>
>>>>>>> Kaz
>>>>>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: ipsec-bounces@ietf.org [mailto:ipsec-bounces@ietf.org] On
>>>>>> Behalf
>>>>>> Of
>>>>>>>> Yaron Sheffer
>>>>>>>> Sent: Friday, March 26, 2010 3:31 AM
>>>>>>>> To: SeongHan Shin
>>>>>>>> Cc: IPsecme WG; Kazukuni Kobara
>>>>>>>> Subject: Re: [IPsec] New PAKE Criteria draft posted
>>>>>>>>
>>>>>>>> Hi Shin,
>>>>>>>>
>>>>>>>> Yes. For the typical remote access VPN, EAP is typically more
>>>>>>>> useful.
>>>>>>>> Note that there is still need for strong password-based mutual
>>>>>>>> authentication EAP methods - but their home is the EMU working
>>>>>>>> group.
>>>>>>>>
>>>>>>>> In addition, the IPsecME has another charter item designed to fit
>>>>>> such
>>>>>>>> EAP methods (such as the future EAP-AugPAKE :-) into IKEv2.
>>>>>>>>
>>>>>>>> Please see again the group's charter,
>>>>>>>> http://tools.ietf.org/wg/ipsecme/charters.
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> 	Yaron
>>>>>>>>
>>>>>>>> On 25.3.2010 20:07, SeongHan Shin wrote:
>>>>>>>>> Dear Yaron Sheffer,
>>>>>>>>>
>>>>>>>>> I have one question about the draft.
>>>>>>>>>
>>>>>>>>> draft-sheffer-ipsecme-pake-criteria-02.txt says in Page 4
>>>>>>>>> "This document is limited to the use of password-based
>>>>>> authentication
>>>>>>>> to
>>>>>>>>> achieve trust between gateways"
>>>>>>>>>
>>>>>>>>> Is this a consensus of this WG?
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>> Shin
>>>>>>>>>
>>>>>>>>> On Thu, Mar 25, 2010 at 3:46 PM, Yaron
>>>>>>>>> Sheffer<yaronf.ietf@gmail.com
>>>>>>>>> <mailto:yaronf.ietf@gmail.com>>    wrote:
>>>>>>>>>
>>>>>>>>>        Hi,
>>>>>>>>>
>>>>>>>>>        after the good discussion in Anaheim, and with the help of
>>>>> comments
>>>>>>>>>        received on and off the list, I have updated the PAKE
>>>>>>>>> Criteria
>>>>>> draft
>>>>>>>>>        and posted it as
>>>>>>>>>
>>>>>>>> http://www.ietf.org/id/draft-sheffer-ipsecme-pake-criteria-02.txt.
>>>>>>>>>
>>>>>>>>>        I have added a number of criteria, clarified others, and
>>>>>>>>> added
>>>>>>>>>        numbering (SEC1-SEC6, IPR1-IPR3 etc.).
>>>>>>>>>
>>>>>>>>>        Thanks,
>>>>>>>>>            Yaron
>>>>>>>>>        _______________________________________________
>>>>>>>>>        IPsec mailing list
>>>>>>>>>        IPsec@ietf.org<mailto:IPsec@ietf.org>
>>>>>>>>>        https://www.ietf.org/mailman/listinfo/ipsec
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> ------------------------------------------------------------------
>>>>>>>>> SeongHan Shin
>>>>>>>>> Research Center for Information Security (RCIS),
>>>>>>>>> National Institute of Advanced Industrial Science and Technology
>>>>>> (AIST),
>>>>>>>>> Room no. 1003, Akihabara Daibiru 10F,
>>>>>>>>> 1-18-13, Sotokannda, Chiyoda-ku, Tokyo 101-0021 Japan
>>>>>>>>> Tel : +81-3-5298-2722
>>>>>>>>> Fax : +81-3-5298-4522
>>>>>>>>> E-mail :
>>>>>>>>> seonghan.shin@aist.go.jp<mailto:seonghan.shin@aist.go.jp>
>>>>>>>>> ------------------------------------------------------------------
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