Outline for April 20, 2004

  1. Example: DG/UX UNIX
    1. Labels and regions
    2. Multilevel directories
    3. File object labels
    4. MAC tuples
  2. BLP: formally
    1. Elements of system: si subjects, oi objects
    2. State space V = B×M×F×H where:
      B set of current accesses (i.e., access modes each subject has currently to each object);
      M access permission matrix;
      F consists of 3 functions: fs is security level associated with each subject, fo security level associated with each object, and fc current security level for each subject
      H hierarchy of system objects, functions h: O->P(O) with two properties:
      If oioj, then h(oi) ∩ h(oj) = Ø
      There is no set { o1, ..., ok } ⊆ O such that for each i, oi+1h(oi) and oi+1 = o1.
    3. Set of requests is R
    4. Set of decisions is D
    5. WR × D × V × V is motion from one state to another.

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