A Theoretical Model of Lock-Keeper Data Exchange and its Practical Verification

Performance is a critical aspect for all kinds of security solutions. The Lock-Keeper is a high-level security solution which implements the concept of physical separation. To evaluate and predict the performance of Lock-Keeper, the internal data transfer process has to be analyzed and simulated. As the Lock-Keeper consists of three independent systems, connected through a hardware-based switch, with file-based communication, the internal data transfer process is relatively complex. In this paper, we propose a mathematical model which can be used to formally represent most of the Lock-Keeper data transfer scenarios. The model is verified by practical experiments for three different application scenarios. We conclude that the performance of the Lock-Keeper system highly depends on the application scenarios.