A Design for a Security-Typed Language with Certificate-Based Declassification

This paper presents a calculus that supports information-flow security policies and certificate-based declassification. The decentralized label model and its downgrading mechanisms are concisely expressed in the polymorphic lambda calculus with subtyping (System F≽). We prove a conditioned version of the noninterference theorem such that authorization for declassification is justified by digital certificates from public-key infrastructures.