Type Based Information Flow Analysis
Francois Pottier  INRIA

Proof using syntax.
  Proof the type system is sound.
  Extend the type system
    reintroduce the marked expression, and so extend the
    type system too.
  Reduction preservers types.
  Together, the soundness of the semantics and that of the
  type system lead to noninterference.

  A symmetric form: expressions that have low-level type and
  that only differ in high-level components have the same
  behavior

Part II, Flow Caml
  demo ...
