The Research on Definition of Multilevel Security Based on the Construction of Covert Channels

Aiming at the main problem that the link between the formal definition of multilevel security and security goal is not always clear, we propose a new definition of multilevel security closer to the practical application. Due to the fact that separability property based on the construction of covert channels is not practical, we introduce the concept of trusted domain to the theoretical framework initiated by the characteristics of transitive and intransitive security policy. Following that two intuitive propositions with the corresponding proof are proposed.