Biba Integrity Model

•      Set of subjects S, objects O, integrity levels I, relation ¡Â Í I ´ I holding when second dominates first

•      min: I ´ I ® I returns lesser of integrity levels 

•      i: S È O ® I gives integrity level of entity

•      r: S ´ O means s Î S can read o Î O

•      w, x defined similarly

Intuition for Integrity Levels

•      The higher the level, the more confidence

–   That a program will execute correctly

–   That data is accurate and/or reliable

•      Note relationship between integrity and trustworthiness

•      Important point: integrity levels are not security levels