Security types for dynamic web data

Abstract

We describe a type system for the Xdπ calculus, introduced in [8]. An Xdπ-network is a network of locations, where each location consists of both a data tree (which contains scripts and pointers to nodes in trees at different locations) and a process, for modelling process interaction, process migration and interaction between processes and data. Our type system is based on types for locations, trees and processes, expressing security levels. The type system enjoys type preservation under reduction (subject reduction). In consequence of subject reduction we prove the following security properties. In a well-typed Xdπ-network, data in a location are accessible only to processes in locations of equal or higher security level. Moreover, processes originating in a location can only go to locations of equal or less security level, with the exception of movements which are returns to the "source" location.