Subject: Re: Last Call: Wireless LAN Certificate Extensions and Attributes to Proposed Standard

From: Thomas Hardjono <[email-masked]>
Date: Tue, 03 Dec 2002 16:00:07 -0500

I'd like to question the wisdom of moving this draft to Proposed
Standard at this time.

It is not clear what the WLAN Industry is needing in terms of the
information to be encoded in cert-extensions or attribute-certs.  Although 
SSID is a good candidate, there is no way to prevent collision of SSIDs in 
HotSpots where multiple W-ISP are providing services.
(nb. perhaps registering them under a naming scheme could work).
In fact, even the inter-WISP roaming model has yet to be established
clearly.

There is also the problem of re-issuance of (all) subscriber certs,
when a W-ISP decides to renumber/rename their SSIDs (e.g. when they
are acquired by another W-ISP).

When a user/subscriber of a W-ISP seeks connectivity, the user really does 
not care about which Authentication Server (AS) is performing 
authentication (ie. identity verification) and which AAA Server is 
providing authorization for the requested service (which in this case
maybe connectivity).  The user is only concerned that he/she is dealing 
with the correct W-ISP (not a bogus one).

Similarly, the W-ISP should control the user's privileges not based on the 
SSID contained in the user-cert, but on the basis of the
(authenticated) identity of the user (e.g. subject name).

(A better goal would be to achieve the scenario where one
client-certificate can be accepted by multiple W-ISPs, regardless of
which SSID is being used in a given HotSpot.  For this to happen,
a common Root CA for inter-WISP roaming is needed.  However, this is
something that maybe beyond the IETF.)

If indeed this ietf-draft is desperately needed to go to Proposed
Standard, I would suggest

(a) renaming it to something more specific,  like: "SSID Extension
     for WLANs".

     Being more specific in the naming of the  draft/RFC prevents
     confusion in the future when other extensions maybe proposed,
     either in the IETF (as a separate draft/RFC) or in other
     Standards Bodies.

(b) making the SSID extension non-critical always (not "at the
     option of the certificate issuer").  This would allow for
     ease of transitioning to these certs.

thomas
------

------------------------------
Thomas Hardjono
Principal Scientist
CTO office
VeriSign
401 Edgewater Place, Suite 280
Wakefield, MA 01880
Tel: 781-245-6996x231
Fax: 781-245-6006
Email: [email-masked]
------------------------------

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From: Russ Housley <[email-masked]>
Date: Wed, 04 Dec 2002 11:23:51 -0500

Thomas:

As you suggesting that Experimental would be better?

Russ

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From: Stephen Kent <[email-masked]>
Date: Thu, 5 Dec 2002 11:44:04 -0500

Thomas,

I think you have raised some good points re the proposed extension 
for wireless LANs, but I strongly disagree with the following 

>something that maybe beyond the IETF.)

I can see why VeriSign might think this is a "better goal," since VS 
might want to serve as a Root CA here just as is does for browsers. 
However, I would not agree that it is a better goal in a broader 
community sense.  We have enough experience with the pitfalls of this 
sort of PKI model in the browser world. Let's not suggest that it be 
repeated in the wireless LAN authentication context too.

Steve

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From: Thomas Hardjono <[email-masked]>
Date: Thu, 05 Dec 2002 15:00:33 -0500

Steve,

(Good to see more discussion on this draft).

At 12/5/2002||11:44 AM, Stephen Kent wrote:
>Thomas,
>
>I think you have raised some good points re the proposed extension for 
>wireless LANs, but I strongly disagree with the following suggestion:
>
>I can see why VeriSign might think this is a "better goal," since VS might 
>want to serve as a Root CA here just as is does for browsers. However, I 
>would not agree that it is a better goal in a broader community sense.  We 
>have enough experience with the pitfalls of this sort of PKI model in the 
>browser world. Let's not suggest that it be repeated in the wireless LAN 
>authentication context too.
>
>Steve

With respect to VeriSign being the Root CA, I have said publicly at several 
presentations (including IEEE802.11 at Vancouver in July and at the recent 
Credentials Provisioning Workshop at IETF55) that the Root CA should be an 
industry organization, such as WECA (Wi-Fi Alliance), PassOne or another body.
Please see Doc 02/401 at 
http://grouper.ieee.org/groups/802/11/Documents/D2T401-450.html

This is the model that is currently adopted for CableModems in the 
broadband industry (under CableLabs as the Root CA).

If you mean (by "PKI Model") the hierarchic model (as compared to the flat 
PGP/web-of-trust model), I would say that many Enterprises -- which are the 
primary business users of 802.11 -- would prefer a hierarchic model.  I 
have not seen the web-of-trust model being adopted by industries who are 
concerned about the protection of their assets and their transactions.

thomas
------

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From: Stephen Kent <[email-masked]>
Date: Thu, 5 Dec 2002 17:36:06 -0500

At 3:00 PM -0500 12/5/02, Thomas Hardjono wrote:
>>I can see why VeriSign might think this is a "better goal," since 
>>VS might want to serve as a Root CA here just as is does for 
>>browsers. However, I would not agree that it is a better goal in a 
>>broader community sense.  We have enough experience with the 
>>pitfalls of this sort of PKI model in the browser world. Let's not 
>>suggest that it be repeated in the wireless LAN authentication 
>>context too.
>>
>>Steve
>
>
>With respect to VeriSign being the Root CA, I have said publicly at 
>several presentations (including IEEE802.11 at Vancouver in July and 
>at the recent Credentials Provisioning Workshop at IETF55) that the 
>Root CA should be an industry organization, such as WECA (Wi-Fi 
>Alliance), PassOne or another body.
>Please see Doc 02/401 at 
>If you mean (by "PKI Model") the hierarchic model (as compared to 
>the flat PGP/web-of-trust model), I would say that many Enterprises 
>-- which are the primary business users of 802.11 -- would prefer a 
>hierarchic model.  I have not seen the web-of-trust model being 
>adopted by industries who are concerned about the protection of 
>their assets and their transactions.

Thomas,

I do like PKI models with some amount of hierarchy, but with a 
hierarchy that parallels existing authorization infrastructures.  As 
most folks know, I am hardly a web of trust kinda' guy :-)  The Cable 
Labs example is an interesting one; because they hold a special 
position in the industry, supprted by the cable box vendors and the 
cable TV operators, they are a good choice for a root CA here. 
Unfottunately, there are few examples where that sort of natural root 
CA role exists, and I think the wireless LAN arena is NOT one of the 
rare exceptions. Also, as we both know, RSA Labs provided the CA 
technology for Cable Labs.  That's a reasonable model, as opposed to 
a TTP CA like VeriSign providing the service for a root CA, which 
would, in my opinion be almost as inappropriate as the more explicit 
CA role that VS plays in the browser context.

Steve