[cap-talk] Confinement Confusion (was: Communicating conspirators)

[Toby Murray]

David Wagner wrote:

>Toby Murray writes:
>  
>
>>Thus, it looks to me that *-property and confinement are inherently 
>>tangled in the minds of many in the community. If anyone out there could 
>>give some history on this I'd certainly be interested to hear it.
>>    
>>
>
>Confinement is the goal.  The *-property is one approach to try to
>meet that goal.  To put it another way, the *-property is a means to
>an end; that end is confinement.
>
>  
>
Ah, that puts things in perspective a bit more. Thanks.

>>Of course that most recent Halevi. Karger. et. al paper also models 
>>confinement using "probabilistic non-interference". Given the huge 
>>number of different variations on non-interference, I feel this only 
>>further confuses things.
>>    
>>
>
>Hmm.  I'm not sure I understand this criticism.  Probabilistic
>non-interference seems to be a reasonable formalism for analyzing covert
>channels and bit-confinement.  Are you saying that use of that formalism
>is likely to spread confusion, among readers who aren't familiar with
>probabilistic non-interference?  That seems plausible, but that's an
>inherent problem with any formalism that isn't universally known.
>
Indeed.
No, I probably ought to retract the above. It doesn't seem to make sense 
now that I read it -- I'm not quite sure what I was trying to say 
anymore. Sorry :)

I guess I was thinking of some of the arguments made in this panel 
abstract from a few years back.
http://csdl2.computer.org/comp/proceedings/csfw/2001/1146/00/11460237.pdf
in which they seem to argue that the notion of non-interference is 
itself hard to pin down. So, my point might have been that not only does 
there seem to be multiple ideas and interpretations about confinement 
itself, but there also seem to be as many different ideas about the 
models used to reason about it.

-- 
Toby Murray
Advanced Computer Capabilities Group
Information Networks Division
DSTO, Australia

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