Enforcing Relaxed Declassifications with Reference Points

Language-based information flow security provides a way to enforce either the baseline noninterference property or more relaxed properties specifying intended information release. This paper presents a new approach for enforcing information release policy on programming language with I/O channels. First we present a relaxed security property complying with the security policy on the what-dimension of declassification. Second we propose an enforcement mechanism for the security property based on reach ability analysis of pushdown system. The self-composition is equipped with a store-match pattern, which reduces the cost of verification by avoiding duplication of I/O channels. The pattern also facilitates characterization of the security property. The experimental results show the preciseness of our enforcement.