Outline for March 10, 2006

Reading: text, §15.1–15.3

1. Greetings and felicitations!
   1. Puzzle of the day
2. Access Control Lists
   1. UNIX method
   2. ACLs: describe, revocation issue
3. Capabilities
   1. Capability-based addressing: show picture of accessing object
   2. Show process limiting access by not inheriting all parent's capabilities
   3. Revocation: use of a global descriptor table
4. Privilege in Languages
   1. Nesting program units
   2. Temporary upgrading of privileges
5. Lock and Key
   1. Associate with each object a lock; associate with each process that has access to object a key (it’s a cross between ACLs and C-Lists)
   2. Example: use crypto (Gifford). X object enciphered with key K. Associate an opener R with X. Then:
      OR-Access: K can be recovered with any D_i in a list of n deciphering transformations, so R = (E₁(K), E₂(K), ..., E_n(K)) and any process with access to any of the D_i’s can access the file
      AND-Access: need all n deciphering functions to get K: R = E₁(E₂(...E_n(K...))
   3. Types and locks