eap Mailing List: RE: Strawman -10/EMSK deletion requirement?

[Avi Lior (avi]

Joe,

See inline.... 

> -----Original Message-----
> From: Salowey, Joe [mailto:jsalowey [at] cisco.com] 
> Sent: Thursday, March 09, 2006 11:51 PM
> To: Avi Lior; Narayanan, Vidya; Jari Arkko
> Cc: eap [at] frascone.com
> Subject: RE: [eap] Strawman -10/EMSK deletion requirement?
> 
>  
> 
> > > The
> > > EMSK MUST NOT be transported out of the EAP (AAA?) Layer 
> and MUST be 
> > > deleted when the corresponding EAP session expires.
> > 
> > Replace EAP (AAA?) with EAP Authentication Server; and 
> "corresponding 
> > EAP session expires" with 'corresponding session has ended'.
> > 
> > Motivation for above: Not sure if EAP session is defined; and you 
> > delete the EMSK when the session is terminated either because it 
> > expired or because it was explicitly terminated.
> > 
> 
> [Joe] I think we will probably need mopre definition around this. 

[Avi] Okay.

> > > Further, an EMSK MUST NOT be used to generate more than one 
> > > AMSK for a given application. 
> > 
> > I am not sure that the above does not pose a threat.  
> > Normally we would
> > think that one Application would require one AMSK.  But since 
> > we are not
> > defining what an application is -- and we shouldn't IMO 
> enter that rat
> > hole.  Then what if there was some application that requires an two
> > AMSKs.?  Is there harm?
> > 
> 
> [Joe] If they are generated at the same time I don't think there is a
> problem.  If there is a delay in generation where the application
> requires the EMSK to be cached it is less than optimal.  
> 
[Avi] In another email thread we explored this further and the way I
understand it is that an Application can have one AMSK key because:

FOO-AMSK = KGF(EMSK,"FOO" | ... | ...)

"FOO" is a the Key Lable and it must be unique.

FOO-A-AMSK = KGF(EMSK,"FOO-A" |  ... | ...)
FOO-B-AMSK = KGF(EMSK,"FOO-B" |  ... | ...)

Are really two differnet AMSKs and this is legal because these are
viewed as two separate applications.

And 
FOO-A-AMSK = KGF(EMSK,"FOO" | "A" | ...)
FOO-B-AMSK = KGF(EMSK,"FOO" | "B" | ...)

Generates two distinct keys but SHOULD not be legal. 

I am not sure if this is defined correctly.

Finally,  I am not sure how this has to do with EMSK caching or not.