Protection in an information processing utility

In this paper we will define and discuss a solution to some of the problems concerned with protection and security in an information processing utility. This paper is not intended to be an exhaustive study of all aspects of protection in such a system. Insteadj we concentrate our attention on the problems of protecting both user and system information (procedures and data) during the execution of a process. We will give special attention to this problem when shared procedures and data are permitted.