[cap-talk] Communicating Conspirators impossibility statements

[Jed at Webstart]

Mark,

I noticed in your page:

http://www.erights.org/elib/capability/conspire.html

a section: "Other Statements of the Same Impossibility".

I'd like to draw your attention to this statement:

http://www.webstart.com/jed/papers/Managing-Domains/#s6 (1981)

substantively:

"To see the difficulty of restricting capability passing 
<delegation>, we need only consider processes A, B, and S pictured in 
fig. 3. Suppose that A has a capability to a resource serviced by S. 
Also suppose that A can communicate with B (if not, then A cannot 
pass anything to B, so no special capability-passing restriction is 
necessary). If a monitoring OS kernel has denied the mechanism for 
passing direct access to a resource from A to B, A can still give B 
the right to indirect access. A can simply have B send all its 
service requests to A for forwarding to S. A will also have to return 
the results of such requests to B."

<here's figure 3: 
http://www.webstart.com/jed/papers/Managing-Domains/Figure-3-50.gif >

which I believe is the same statement with the same 'proof' as that 
from your "conspire" page.

If you believe there are substantive differences I'd be interested to 
hear what they are.

I believe you'd find that Managing Domains paper of general interest, 
particularly from section 4:

http://www.webstart.com/jed/papers/Managing-Domains/#s4

on for a bit (e.g. through section 13 or 14) if you haven't taken 
time to read it.

--Jed http://www.nersc.gov/~jed/