Protection in Operating Systems

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.

CACM August, 1976

Harrison, M. A.
Ruzzo, W. L.
Ullman, J. D.

protection, protection system, operating
system, decidability, Turing machine

4.30 4.31 5.24

CA760804 JB January 4, 1978  10:12 AM

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