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© 2004 Ravi Sandhuwww.list.gmu.edu
The Typed Access Matrix Model (TAM) and Augmented TAM (ATAM)
Ravi SandhuLaboratory for Information Security Technology
George Mason Universitywww.list.gmu.edusandhu@gmu.edu
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© 2004 Ravi Sandhuwww.list.gmu.edu
Outline
• TAM: Typed Access Matrix Model• TAM adds types to HRU and preserves strong safety
results of SPM/ESPM• SO-TAM: Single Object TAM
• SO-TAM manipulates one column of the access matrix at a time and is equivalent to TAM
• ATAM: Augmented TAM• ATAM adds testing for absence of rights to TAM• ATAM is equivalent to TAM in one sense but more
expressive in another
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© 2004 Ravi Sandhuwww.list.gmu.edu
TAM adds types to HRU
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© 2004 Ravi Sandhuwww.list.gmu.edu
TAM adds types to HRU
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TAM commands
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TAM primitive operations
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TAM operations: enter and delete
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TAM operations: create and destroy
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TAM operations: create and destroy
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ORCON in TAM
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ORCON in TAM
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ORCON in TAM
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ORCON in TAM
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MTAM: Monotonic TAM
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MTAM Canonical Schemes
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MTAM Canonical Schemes
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ORCON as a MTAM Canonical Scheme
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Acyclic TAM schemes
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Acyclic TAM unfolded state
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Acyclic MTAM unfolded state
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Acyclic MTAM safety
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Ternary MTAM
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Ternary MTAM
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Binary and Unary MTAM
• Unary MTAM• Useless
• Binary MTAM• Single-parent creation or spontaneous double-
child creation• Less expressive than multi-parent creation
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SOTAM: single object TAM
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SOTAM
• SOTAM is equivalent in expressive power to TAM
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© 2004 Ravi Sandhuwww.list.gmu.edu
ATAM: Augmented TAM
• Allow testing for absence of rights in the conditions of commands
• ATAM is equivalent in expressive power to TAM in unbounded simulation but most likely not in bounded simulation• “Most likely not” has recently been shown to be
“provably cannot”
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