Preface

Abstract

Trusted and secure computing properties of computer system are usually believed to behave in a well-defined way and enable the processed information to be  properly protected. Nowadays, the need to protect information is increasing, particularly on the type of computers that we use directly for processing data with different levels of sensitivity. A computing system that supports multiple levels of security (MLS) provides the protections to guarantee that information which is assigned to different security levels is handled appropriately. The problem of processing information with different levels of sensitivity has been extensively studied since the early 70s of the twentieth century. To ensure the confidentiality and integrity of information, there are often used several models (B-LP, Biba, Clark-Wilson), which provide mandatory access control (MAC) entity (called subject) to the resource (called object). (...)