It concentrates on those architectural structures--whether hardware or software--that are necessary to
support information protection. The paper develops in three main sections. Section I describes desired functions,
design principles, and examples of elementary protection and authentication mechanisms. Any reader familiar with
computers should find the first section to be reasonably accessible. Section II requires some familiarity with
descriptor-based computer architecture. It examines in depth the principles of modern protection architectures and
the relation between capability systems and access control list systems, and ends with a brief analysis of protected
subsystems and protected objects. The reader who is dismayed by either the prerequisites or the level of detail in the
second section may wish to skip to Section III, which reviews the state of the art and current research projects and
provides suggestions for further reading.