[OpenAFS] Open AFS, SSL and wireless security.

[Tim O'Callaghan]

> 
> 
> SEND ALL REPLIES TO THE LIST!
> 

Doh !

> "Tim O'Callaghan" <tim.ocallaghan@limestudios.com> writes:
> 
> > > Well, it depends very much on your threat model.  First,
> encryption
> > > is only used when you have a token (e.g. files with a
> system:anyuser
> > > ACL accessed from an un-authenticated context are not
> protected).
> > > Second, the encryption used is NOT perfect, but it's certainly
> > > better than sending along clear-text.
> > > 
> > 
> > Hmm... "threat model" is a new term to me. I'm just a
> paranoid hacker
> > wanting to secure my home (and personal office space)
> > communications.... Ok, after a quick google, there it is (I think).
> 
> A "threat model" is a description of what you are worried
> about, what attacks you care about (and specifically what 
> attacks you DON'T care about).  Are you worried that your 
> neighbor will read your packets by sniffing your wireless?  
> Or are you worried that the NSA will do so? The security 
> required to protect yourself against the NSA is VERY 
> DIFFERENT than the security required to protect yourself 
> against your neighbor.
> 

If the UK government wanted info from my machine, they would come and 
take my machine. Hmm... Have to think about what would happen if someone

stole my machine... But anyway the threat model here is domestic. 

<snip network diagram etc/>
> 
> Well, again, it depends...  Who do you expect is listening?  
> Kerberos uses lots of keys -- there is the long term key 
> which is used once every 10 hours, and then a bunch of random 
> session keys which last for only 10 hours.  And then 
> sub-session keys which last even shorter periods of time.  So 
> the REAL question is: do you think that someone will be able 
> to grab enough traffic to crack a sub-session key during the 
> lifetime of a session?  Or do you think that someone will 
> grab enough Kerberos traffic to crack your long term key?
> 

Depends... Approx how many transmissions do you need to have a crack at
a long 
term key?

> This depends on your actual threat model.  Could the NSA do 
> it?  Yea. But they could also do it with SSL, too ;) 
> Could your neighbor? HIGHLY unlikely.  
My neighbour represents a constant threat, as they will be there for the
long term, and hence 
have much more of an opportunity to have a crack at it. 
Would they? no idea. 
Could they? assuming i patch regularily, as you say highly unlikley. But
in general, i prefer to be on the moderate side of paranoid, more of a
hobby than a career :)

If NSA/M15/M$ were determined, they would use normal surveillance. Put
some kind of 
transmitter in my keyboard or key logger dongle or similar, simpler
method.

> And as OpenAFS moves forward 
> with more Krb5 work the strength of AFS authentication and 
> encryption will increase.
> 
> Theoretically?  Of course.. As I said, nothing is perfectly 
> secure. Is it computationally feasible?  Well, that depends 
> on your threat model.
> 
> > Whereas if I use an encrypted underlying transport (e.g. stunnel) I 
> > might avoid having D compromosed....
> 
> No, but you have your SSL key potentially compromised...  
> STunnel is not inherently more secure that Kerberos... It's 
> just painting the fence a different color (would you prefer 
> white or green paint?)
> 

By my way of thinking (again I'm only a layman) they'd have to crack my 
SSL and then have a crack at openAFS & Kerberos(?)

> > >
> > > So, I cannot answer your "would this be vulnerable" question
> > > without knowing your views of your threat model, answering 
> > > "vulnerable to what attacks?"
> > > 
> > 
> > Hope this explains it in a bit more detail. At the moment I 
> have not 
> > detected anyone in wireless range, but its only a matter of time....
> 
> Sort of... But please... KEEP THIS ON THE LIST!  Unless your 
> goal is to hire me as a security consultant, at which point 
> we can take this off list and talk about rates.
> 

many appologies..

Tim.