Outline for January 15, 2007
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Greetings and Felicitations!
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Stealing
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Definition: can·steal(r, x, y, G0) true iff there is no edge from x to y labeled r in G0, and there exists a sequence of protection graphs G0, ..., Gn such that G0 |-* Gn in which:
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Gn has an edge from x to y labeled r
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There is a sequence of rule applications ρ1, ..., ρn such that Gi-1 |- Gi; and
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For all vertices v, w in Gi-1, if there is an edge from v to y in G0 labeled r, then ρi is not of the form "v grants (r to y) to w"
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Example
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Theorem: can·steal(r, x, y, G0) iff all of the following hold:
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there is no edge from x to y labeled r in G0;
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there is a subject x′ which initially spans to x, or x′ = x; and
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there is a vertex s with an edge to y labeled r in G0 and for which can·share(t, x, s, G0) holds
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Conspiracy
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Access set
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Deletion set
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Conspiracy graph
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I, T sets
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Theorem: can·share(r, x, y, G0) iff there is a path from some h(p) ∈ I(x) to some h(q) ∈ T(y)
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Schematic Protection Model
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Model components
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Link function
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Filter function
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Example: Take-Grant as an instance of SPM
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Create operations and attenuation
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Flow functions, maximal state
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Safety analysis
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