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Safety Problem Resolver. A special tool was developed for interpreting and process-
ing the SPSL-specifications, named a safety problem resolver (SPR). SPR is a logical
machine based on the Prolog kernel. It gets SPSL specification and uses the logical
rules for resolution. We can apply SPR to a safety problem solving as it is described
below (Fig. 3).
If we need to evaluate given system state
S Σ by the model criteria C , we can
put the system state
and criteria C to SPR and determine its safety according to
the security criteria C : ∀ c C : c ( s = D (
)) = true . We make the assumption that the
system security mechanism implements the access control R properly.
If we need to generate the states
S Σ reachable from
and evaluate their
S Σ , access rules R and security criteria
safety, we need to put the current state
C , and produce all the states
reachable from
and test their security in two
stages:
1. ∀
+
+
+
S Σ :
,
= T ( q ,
) ∃ s i = D (
), s i +1 = D (
)
and ∀ r R : r ( s i , s i +1 ) = true
2. ∀
S Σ :
is reachable from
, s i = D (
):∀ c C : c ( s i ) = true
￿
￿
￿
!
"
￿
init
￿
s
#$
Fig. 3. Safety Problem Resolver
Safety Evaluation Workshop
Evaluation Framework Structure
On the basis of SPR we build a number of tools, which bring the process of safety
evaluation to the routine procedure:
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