Schematic Protection Model." Journal of Computer Security, to appear. #5# Ammann, P.E., Lipton, R.J. and Sandhu, R.S. Private communication. #6# Bell, D.E. and LaPadula, L.J. #Secure Computer Systems: Uni#ed Exposition and Multics Interpretation. " MTR-2997, MITRE #1975#.  Home/Search   Document Not in Database   Summary   Related Articles

....reversible#. In this paper we de#ne the typed access matrix #TAM# model by introducing strong typing into HRU #i.e. each subject or object is created to be of a particular type which thereafter does not change#. We prove that monotonic TAM #MTAM# has strong safety properties similar to Sandhu s Schematic Protection Model. Safetyin MTAM s decidable case is, however, NP hard. We develop a model called ternary MTAM which has polynomial safety for its decidable case, and which nevertheless retains the full expressivepower of MTAM. There is compelling evidence that the decidable safety cases of ternary MTAM are quite ....

....TAM #MTAM# has decidable, but NPhard, safety for its acyclic creation cases. Further, wehave shown that ternary MTAM has polynomial time safety analysis for its acyclic cases, even though it is in general equivalenttoMTAM. Ternary MTAM thus has strong safety properties similar to those of Sandhu s Schematic Protection Model #21, 22, 23# and its recent extension by Ammann and Sandhu#2,3,4#. The expressivepower of ternary MTAM has been shown to be equivalenttoMTAM in general. Our results establish that #i# strong typing is crucial to achieving a useful demarcation between decidable and undecidable safety, and #ii# ....

Schematic Protection Model." Journal of Computer Security, to appear. #5# Ammann, P.E., Lipton, R.J. and Sandhu, R.S. Private communication. #6# Bell, D.E. and LaPadula, L.J. #Secure Computer Systems: Uni#ed Exposition and Multics Interpretation. " MTR-2997, MITRE #1975#.

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