Producing secure digital information systems

The security of a digital information system is determined by the process that produces the system. Thus, it is argued that the system production process is the central issue in achieving secure systems. A rigorous approach to digital system engineering is described which is based on a mathematical function that accurately and completely describes the physical behavior of the digital device in question. It is concluded that two critical steps needed to enable this rigorous approach to engineering secure digital systems are: to provide digital hardware whose behavior conforms to a mathematical function; and to provide a clear, precise statement of what that function is