# Outline for April 15, 2004

1. Policy
1. Policy languages: high level, low level
2. Bell-LaPadula Model (security classifications only)
1. Go through security clearance, classification
2. Describe simple security condition (no reads up), *-property (no writes down), discretionary security property
3. State Basic Security Theorem: if it's secure and transformations follow these rules, it's still secure
1. Go through security clearance, categories, levels
4. Lattice models
1. Poset, ≤ the relation
2. Reflexive, antisymmetric, transitive
3. Greatest lower bound, least upper bound
4. Example with complex numbers
1. Apply lattice work
1. Set of classes SC is a partially ordered set under relation ≤ with GLB (greatest lower bound), LUB (least upper bound) operators
2. Note: is reflexive, transitive, antisymmetric
3. Examples: (A, C) ≤ (A´, C´) iff A ≤ A´ and C ⊆ C´;
LUB((A, C), (A´, C´)) = (max(A, A´), C ∪ C´), GLB((A, C), (A´, C´)) = (min(A, A´), C ∩ C´)
2. Describe simple security condition (no reads up), *-property (no writes down), discretionary security property
3. State Basic Security Theorem: if it's secure and transformations follow these rules, it's still secure
4. Maximum, current security level
6. Example: DG/UX UNIX
1. Labels and regions
2. Multilevel directories