Abstract
Under the premise that there is a tradeoff between the amount of protection within a computer system and the system cost, this paper investigates some theoretical measures of protection within systems. A system simply consists of any number of active elements, called subjects, that make use of passive elements, called objects. The investigation is restricted to an analysis and comparison of access mechanisms defined by a family of boolean functions. Some definitions are stated, and some theorems are proved that are valid for all mechanisms within the family considered. Algorithms are presented for the optimal assignment of access codes to subjects are objects for unstructured systems and for several types of structured systems. It is proven that for a very general class of systems, the optimal assignment will still allow at least (n/2)(γ- 1) unauthorized accesses to objects, wheren is the number of subjects, and γ is the largest integer not greater than the quantityn divided by the number of access classes.
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This work was partially supported by NSF Grant GJ-660.
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Ellis, C.A. Analysis of some abstract measures of protection in computer systems. International Journal of Computer and Information Sciences 7, 219–251 (1978). https://doi.org/10.1007/BF00991632
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DOI: https://doi.org/10.1007/BF00991632