Visible to the public Protection in Operating Systems

TitleProtection in Operating Systems
Publication TypeJournal Article
Year of Publication1976
AuthorsHarrison, Michael A., Ruzzo, Walter L., Ullman, Jeffrey D.
JournalCommun. ACM
Keywordsdecidability, operating system, protection, protection system, Science of Security Significant Paper, Turing machine

A model of protection mechanisms in computing systems is presented and its appropriateness is argued. The "safety" problem for protection systems under this model is to determine in a given situation whether a subject can acquire a particular right to an object. In restricted cases, it can be shown that this problem is decidable, i.e. there is an algorithm to determine whether a system in a particular configuration is safe. In general, and under surprisingly weak assumptions, it cannot be decided if a situation is safe. Various implications of this fact are discussed.


This article was identified by the SoS Best Scientific Cybersecurity Paper Competition Distinguished Experts as a Science of Security Significant Paper.

The Science of Security Paper Competition was developed to recognize and honor recently published papers that advance the science of cybersecurity. During the development of the competition, members of the Distinguished Experts group suggested that listing papers that made outstanding contributions, empirical or theoretical, to the science of cybersecurity in earlier years would also benefit the research community.

Original Publication
Citation KeyHarrison:1976:POS:360303.360333