Subject: [abfab] Issue 28 - AAA protection of the MSK

From: "Tschofenig, Hannes (NSN - FI/Espoo)" <[email-masked]>
Date: Sat, 17 Dec 2011 18:49:12 +0200

Hi Jim, 

in issue #28 http://trac.tools.ietf.org/wg/abfab/trac/ticket/28 you
wrote:

"
The document needs to discuss the protections (or lack there of) for the
MSK as it travels from the IdP to the RP. Known issues are:
1.	In RADIUS the security (encryption and authentication) is hop to
hop -so in theory any AAA proxy can decrypt the messages. 
2.	In Diameter there is no(?) current ability to encrypt either hop
to hop or end-to-end. 
" 

The standardized and deployed security protection in RADIUS and Diameter
is hop-by-hop. Hence, the AAA messages can be read by AAA
intermediaries, which is the intention for most of the payload but not
for the MSK. 

Luckily, the MSK itself does not help these intermediaries since they do
not get to see the data traffic that is protected with the MSK (or keys
derived from the MSK).

Nevertheless, it may be useful to point to
http://tools.ietf.org/html/rfc4962 for a discussion of the security of
the AAA key management. It is currently not referenced by the document. 

Ciao
Hannes