Availability: theory and fundamentals for practical evaluation and use

What the currently available security criteria are still missing is a functional structure of the concept of availability. The intention of the article is to define a functional structure of the concept of availability in terms of basic functions, similar to the Generic Headings in the ITSEC (IT Security Criteria). The article gives the basic definitions and terms as well as a terminological introduction. It contains a list of possible threats, with a view to technical and human failure. These threats are compared with possible security functions. Examples are given of the technical implementation of these security functions (defined as mechanisms). A first approach for evaluation, based on ITSEC is also presented