Clark-Wilson Integrity Model

•      Integrity defined by a set of constraints

–    Data in a consistent or valid state when it satisfies these

•      Example: Bank

–    D today’s deposits, W withdrawals, YB yesterday’s balance, TB today’s balance

–    Integrity constraint: D + YB –W

•      Well-formed transaction move system from one consistent state to another

•      Issue: who examines, certifies transactions done correctly?

Entities

•      CDIs: constrained data items

–    Data subject to integrity controls

•      UDIs: unconstrained data items

–    Data not subject to integrity controls

•      IVPs: integrity verification procedures

–    Procedures that test the CDIs conform to the integrity constraints

•      TPs: transaction procedures

–    Procedures that take the system from one valid state to another