The exchange of sensitive information in many systems over a network can be manipulated
by unauthorized access. Opacity is a property to investigate security and
privacy problems in such systems. Opacity characterizes whether a secret information
of a system can be inferred by an unauthorized user. One approach to verify security
and privacy properties using opacity problem is to model the system that may leak confidential
information as a discrete event system. The problem that has not investigated
intensively is the enforcement of opacity properties by supervisory control. In other
words, constructing a minimally restrictive supervisor to limit the system's behavior so
an unauthorized user cannot discover or infer the secret information.
We describe and analyze the complexity of opacity in systems that are modeled as
a discrete event system with partial observation mapping. We define three types of
opacity: strong opacity, weak opacity, and no opacity. Strong Opacity describes the
inability for the system's observer to know what happened in a system. On the other
hand, No-opacity refers to the condition where there is no ambiguity in the system
behavior. The definitions introduce properties of opacity and its effects on the system
behavior. Strong opacity can be used to study security related problems while no opacity
can be used to study fault, detection and diagnosis, among many other applications. In
this dissertation, we investigate the largest opaque sublanguages and smallest opaque
superlanguages of a language if the language is not opaque. We studied how to ensure
strong opacity, weak opacity and no opacity by supervisory control. If strong opacity,
weak opacity or no opacity is not satisfied, then we can restrict the system's behavior by a
supervisor so that strong opacity, weak opacity or no opacity is satisfied. We investigate
the strong opacity control problem (SOCP), the weak opacity control problem (WOCP),
and no opacity control problem (NOCP).
As illustrated by examples in the dissertation, the above properties of opacity can
be used to characterize the security requirements in many applications, as anonymity
requirements in protocols for web browsing. Solutions to SOCP in terms of the largest
sublanguage that is controllable, observable (or normal), and strongly opaque were characterized.
Similar characterization is available for solutions to NOCP.
","abstract_html":"<p>The exchange of sensitive information in many systems over a network can be manipulated</p> <p>by unauthorized access. Opacity is a property to investigate security and</p> <p>privacy problems in such systems. Opacity characterizes whether a secret information</p> <p>of a system can be inferred by an unauthorized user. One approach to verify security</p> <p>and privacy properties using opacity problem is to model the system that may leak confidential</p> <p>information as a discrete event system. The problem that has not investigated</p> <p>intensively is the enforcement of opacity properties by supervisory control. In other</p> <p>words, constructing a minimally restrictive supervisor to limit the system's behavior so</p> <p>an unauthorized user cannot discover or infer the secret information.</p> <p>We describe and analyze the complexity of opacity in systems that are modeled as</p> <p>a discrete event system with partial observation mapping. We define three types of</p> <p>opacity: strong opacity, weak opacity, and no opacity. Strong Opacity describes the</p> <p>inability for the system's observer to know what happened in a system. On the other</p> <p>hand, No-opacity refers to the condition where there is no ambiguity in the system</p> <p>behavior. The definitions introduce properties of opacity and its effects on the system</p> <p>behavior. Strong opacity can be used to study security related problems while no opacity</p> <p>can be used to study fault, detection and diagnosis, among many other applications. In</p> <p>this dissertation, we investigate the largest opaque sublanguages and smallest opaque</p> <p>superlanguages of a language if the language is not opaque. We studied how to ensure</p> <p>strong opacity, weak opacity and no opacity by supervisory control. If strong opacity,</p> <p>weak opacity or no opacity is not satisfied, then we can restrict the system's behavior by a</p> <p>supervisor so that strong opacity, weak opacity or no opacity is satisfied. We investigate</p> <p>the strong opacity control problem (SOCP), the weak opacity control problem (WOCP),</p> <p>and no opacity control problem (NOCP).</p> <p>As illustrated by examples in the dissertation, the above properties of opacity can</p> <p>be used to characterize the security requirements in many applications, as anonymity</p> <p>requirements in protocols for web browsing. Solutions to SOCP in terms of the largest</p> <p>sublanguage that is controllable, observable (or normal), and strongly opaque were characterized.</p> <p>Similar characterization is available for solutions to NOCP.</p>","abstract_has_math":false,"creators":["Ben Kalefa, Majed Mohamed"],"institution":null,"degree_name":"Ph.D.","degree_level":"Open Access Dissertation","degree_discipline":"Electrical and Computer Engineering","degree_department":null,"school":null,"contributors":["Feng Lin"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-01-01T08:00:00Z","date_published":"2013-01-01T08:00:00Z","updated_at":"2026-07-24T05:59:33Z","subjects":["discrete event system","opacity","security","Computer Sciences","Electrical and Computer Engineering"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.wayne.edu/oa_dissertations/830","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Feng Lin"]},{"key":"dc:creator","label":"Author","values":["Ben Kalefa, Majed Mohamed"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2013-01-01T08:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical and Computer Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Open Access Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["discrete event system","opacity","security","Computer Sciences","Electrical and Computer Engineering"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.wayne.edu/oa_dissertations/830"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The exchange of sensitive information in many systems over a network can be manipulated
by unauthorized access. Opacity is a property to investigate security and
privacy problems in such systems. Opacity characterizes whether a secret information
of a system can be inferred by an unauthorized user. One approach to verify security
and privacy properties using opacity problem is to model the system that may leak confidential
information as a discrete event system. The problem that has not investigated
intensively is the enforcement of opacity properties by supervisory control. In other
words, constructing a minimally restrictive supervisor to limit the system's behavior so
an unauthorized user cannot discover or infer the secret information.
We describe and analyze the complexity of opacity in systems that are modeled as
a discrete event system with partial observation mapping. We define three types of
opacity: strong opacity, weak opacity, and no opacity. Strong Opacity describes the
inability for the system's observer to know what happened in a system. On the other
hand, No-opacity refers to the condition where there is no ambiguity in the system
behavior. The definitions introduce properties of opacity and its effects on the system
behavior. Strong opacity can be used to study security related problems while no opacity
can be used to study fault, detection and diagnosis, among many other applications. In
this dissertation, we investigate the largest opaque sublanguages and smallest opaque
superlanguages of a language if the language is not opaque. We studied how to ensure
strong opacity, weak opacity and no opacity by supervisory control. If strong opacity,
weak opacity or no opacity is not satisfied, then we can restrict the system's behavior by a
supervisor so that strong opacity, weak opacity or no opacity is satisfied. We investigate
the strong opacity control problem (SOCP), the weak opacity control problem (WOCP),
and no opacity control problem (NOCP).
As illustrated by examples in the dissertation, the above properties of opacity can
be used to characterize the security requirements in many applications, as anonymity
requirements in protocols for web browsing. Solutions to SOCP in terms of the largest
sublanguage that is controllable, observable (or normal), and strongly opaque were characterized.
Similar characterization is available for solutions to NOCP.
"]},{"key":"dc:title","label":"Title","values":["Opacity Of Discrete Event Systems: Analysis And Control"]}]}],"canonical_facts":{"dc:contributor":["Feng Lin"],"dc:creator":["Ben Kalefa, Majed Mohamed"],"dc:date.available":["2013-01-01T08:00:00Z"],"dc:description.abstract":["The exchange of sensitive information in many systems over a network can be manipulated
by unauthorized access. Opacity is a property to investigate security and
privacy problems in such systems. Opacity characterizes whether a secret information
of a system can be inferred by an unauthorized user. One approach to verify security
and privacy properties using opacity problem is to model the system that may leak confidential
information as a discrete event system. The problem that has not investigated
intensively is the enforcement of opacity properties by supervisory control. In other
words, constructing a minimally restrictive supervisor to limit the system's behavior so
an unauthorized user cannot discover or infer the secret information.
We describe and analyze the complexity of opacity in systems that are modeled as
a discrete event system with partial observation mapping. We define three types of
opacity: strong opacity, weak opacity, and no opacity. Strong Opacity describes the
inability for the system's observer to know what happened in a system. On the other
hand, No-opacity refers to the condition where there is no ambiguity in the system
behavior. The definitions introduce properties of opacity and its effects on the system
behavior. Strong opacity can be used to study security related problems while no opacity
can be used to study fault, detection and diagnosis, among many other applications. In
this dissertation, we investigate the largest opaque sublanguages and smallest opaque
superlanguages of a language if the language is not opaque. We studied how to ensure
strong opacity, weak opacity and no opacity by supervisory control. If strong opacity,
weak opacity or no opacity is not satisfied, then we can restrict the system's behavior by a
supervisor so that strong opacity, weak opacity or no opacity is satisfied. We investigate
the strong opacity control problem (SOCP), the weak opacity control problem (WOCP),
and no opacity control problem (NOCP).
As illustrated by examples in the dissertation, the above properties of opacity can
be used to characterize the security requirements in many applications, as anonymity
requirements in protocols for web browsing. Solutions to SOCP in terms of the largest
sublanguage that is controllable, observable (or normal), and strongly opaque were characterized.
Similar characterization is available for solutions to NOCP.
"],"dc:identifier":["https://digitalcommons.wayne.edu/oa_dissertations/830"],"dc:subject":["discrete event system","opacity","security","Computer Sciences","Electrical and Computer Engineering"],"dc:title":["Opacity Of Discrete Event Systems: Analysis And Control"],"thesis:degree_discipline":["Electrical and Computer Engineering"],"thesis:degree_level":["Open Access Dissertation"],"thesis:degree_name":["Ph.D."]},"updated_at":"2026-07-24T05:59:33Z"}