Dynamic IFC Theorems for Free

We show that noninterference and transparency, the key soundness theorems for dynamic IFC libraries, can be obtained "for free", as direct consequences of the more general parametricity theorem of type abstraction. This allows us to give very short soundness proofs for dynamic IFC libraries such as faceted values and LIO. Our proofs stay short even when fully mechanized in the Agda proof assistant. Moreover, our proofs cover the actual Agda implementations of the libraries, not just an abstract model.