Subject: [Dime] Quick look at draft-ietf-dime-ikev2-psk-diameter-00.txt

From: "Tschofenig, Hannes (NSN - FI/Espoo)" <[email-masked]>
Date: Fri, 15 Jan 2010 00:15:09 +0200

Hi Avi, 

I have three comments at this point in time:

1) Editorial 

There is some room for improvement on the editorial side. An example: 

FROM:

Abstract

   Internet Key Exchange is a component of IPsec used for performing
   mutual authentication as well as establishing and maintaining
   security associations (SAs) between two parties such as a user and a
   network entity.  Internet Key Exchange v2 (IKEv2) protocol allows
   several different mechanisms for authenticating a user, namely the
   Extensible Authentication Protocol, certificates, and pre-shared
   secrets.  To authenticate and/or authorize the user, the network
   element such as the Access Gateway may need to dynamically bootstrap
   a security association based on interaction with the Diameter server.
   This document specifies the interaction between the Access Gateway
   and Diameter server for the IKEv2 based on pre-shared secrets.

TO:

"
Abstract

   The Internet Key Exchange protocol version 2 (IKEv2) is a component
of 
   the IPsec architecture and used to perform mutual authentication as
well 
   as to establish and to maintain IPsec security associations (SAs)
between 
   the respective parties. IKEv2 supports several different
authentication 
   mechanisms, such as the Extensible Authentication Protocol (EAP), 
   certificates, and pre-shared secrets. 

   With TBD-RFC the Diameter interworking for Mobile IPv6 between the
Home 
   Agent, as a Diameter client, and the Diameter server has been
specified. 
   However, that specification focused on the usage of EAP and did not 
   include support for pre-shared secret based authentication available 
   with IKEv2. This document therefore extends the functionality offered

   by TBD-RFC with pre-shared key based authentication offered by IKEv2 
   when no EAP is used.
"

2) Reuse of draft-ietf-dime-local-keytran-00.txt

Instead of defining your own key related AVP wouldn't it make sense to
reuse what has been defined in
http://www.ietf.org/id/draft-ietf-dime-local-keytran-00.txt ? 

3) Security

The security in the document is a bit fuzzy to me. I believe what you
are saying is essentially that the pre-shared key isn't really the
user's long-term shared key but rather something that has been
dynamically established (and thus short lived) based on a previous
network access authentication run (or something like that). Is my
understanding correct?

In any case, I believe it would be helpful to go through the Housley
criteria as a guide for the text that one might want to find in the
security consideration sections of such a document. This helps to point
out some security threats in a more structured fashion. Does this make
sense to you? 

Ciao
Hannes