Software mediators for transparent channel control in unbounded environments

Establishing verifiably secure communications is a daunting task, especially in unbounded computing networks such as the Internet and the global information grid. The multiple independent levels of security (MILS) architecture has been developed to facilitate this task. Wrappers, filters and mediators, both hardware and software, have been proposed as MILS mechanisms to enforce communication security policies such as data isolation and sanitation. This paper describes two experimental projects showing how software mediators can be implemented using CORBA in two different environments: a standard Unix TCP/IP network with multiple workstations, and a single board computer running the integrity operating system with a separation kernel supporting multiple isolated execution environments. The first example shows how protocol mediators can enforce communication-related security policies on standard networks, while the second shows that same functionality implemented on a MILS-based architecture. The projects show how transparent communication security policies can be implemented with existing technologies and without any modifications to the operating system kernels.