Policy Enforcement in Trusted Execution Environments

Trusted Execution Environments (TEEs) reduce the complexity and scope of modern operating systems by assuming the responsibility for component isolation. TEEs ensure that components on the system remain isolated from each other and, depending on their implementation, even from the underlying operating system. 

While isolation enhances system security, complete isolation is not the solution. In practice, components often need to interact and communicate. Therefore, it becomes necessary to break down these isolation barriers and facilitate communication channels between components.

To achieve this, a coordinating entity is required to determine which components should be loaded and define the communication channels within the system. This necessitates the creation of a system configuration that precisely outlines these requirements. Furthermore certain rules and security goals should be enforced in this system configuration.

In this thesis, we address this challenge by introducing a novel policy description language. This language allows for the straightforward and intuitive expression of rules for system configurations. Additionally, we have developed a policy enforcement and configuration engine capable of automatically evaluating these rules against a system description. Given the diversity in system types, communication channels, architectures, and system scenario representations, we also propose an abstraction concept that separates the system configuration and policy evaluation processes from the actual systems. Our solution is thereby adaptable to a variety of different systems.

(Master Thesis Defense)