Information flow properties for cyber-physical systems

In cyber-physical systems, which are the integrations of computational and physical processes, security properties are difficult to enforce. Fundamentally, physically observable behavior leads to violations of confidentiality. This work analyzes certain noninterference based security properties to ensure that interactions between the cyber and physical processes preserve confidentiality. A considerable barrier to this analysis is the representation of physical system interactions at the cyber-level. This thesis presents encoding of these physical system properties into a discrete event system and represents the cyber-physical system using Security Process Algebra (SPA). The model checker, Checker of Persistent Security (CoPS) shows Bisimulation based NonDeducibility on Compositions (BNDC) properties, which are a variant of noninterference properties, to check the system\u27s security against all potential high-level interactions. This work considers a model problem of invariant pipeline flow to examine the BNDC properties and their applicability for cyber-physical systems--Abstract, page iii

Security analysis of a cyber-physical system

Cyber-Physical Systems (CPSs) are an integration of computing and physical processes. Information flow is an inherent property of CPSs and is of particular interest at their cyber-physical boundaries. This thesis focuses on discovering information flow properties and proposes a process to model the information flow in CPSs. A Cooperating FACTS Power System serves as a tangible example to illustrate modeling information flow using the proposed process. The proposed process can be used to model the information flow security, help analyze current information flow security requirements, and aid in the design of further security policies in CPS --Abstract, page iii

Checking Integrity via CoPS and Banana: the E-Commerce Case Study

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Verification of information flow security in cyber-physical systems

With a growing number of real-world applications that are dependent on computation, securing the information space has become a challenge. The security of information in such applications is often jeopardized by software and hardware failures, intervention of human subjects such as attackers, incorrect design specification and implementation, other social and natural causes. Since these applications are very diverse, often cutting across disciplines a generic approach to detect and mitigate these issues is missing. This dissertation addresses the fundamental problem of verifying information security in a class of real world applications of computation, the Cyber-physical systems (CPSs). One of the motivations for this work is the lack of a unified theory to specify and verify the complex interactions among various cyber and physical processes within a CPS. Security of a system is fundamentally characterized by the way information flows within the system. Information flow within a CPS is dependent on the physical response of the system and associated cyber control. While formal techniques of verifying cyber security exist, they are not directly applicable to CPSs due to their inherent complexity and diversity. This Ph.D. research primarily focuses on developing a uniform framework using formal tools of process algebras to verify security properties in CPSs. The merits in adopting such an approach for CPS analyses are three fold- i) the physical and continuous aspects and the complex CPS interactions can be modeled in a unified way, and ii) the problem of verifying security properties can be reduced to the problem of establishing suitable equivalences among the processes, and iii) adversarial behavior and security properties can be developed using the features like compositionality and process equivalence offered by the process algebras --Abstract, page iii

Through the eyes of the homeless: A study on service utilization

This study examined the causes and reasons for not using services, and needs among people experiencing homelessness in the city of Riverside. In addressing the initial causes and immediate needs of the homeless, current knowledge about services offered from the homeless perspective is very limited

Through the eyes of the homeless: A study on service utilization

This study examined the causes and reasons for not using services, and needs among people experiencing homelessness in the city of Riverside. In addressing the initial causes and immediate needs of the homeless, current knowledge about services offered from the homeless perspective is very limited

The Invisible Walls of The 606: An Examination of the Relationship Between an Urban Greenway and Community Change

With much of the United State population now choosing to live, work, and recreate in urban locations, cities across the county have begun to look for ways to increase green space to meet the ever-growing demand of residents. One way this has been done is through the integration of urban greenways. Unlike other green spaces, these contemporary corridors are constructed in a manner that they directly traverse both densely populated residential communities and commercial spaces. By being built into the fabric of residential areas, these corridors connect residents who often vary in terms of race, socio-economic status, and culture. While these greenways have been shown to provide traversed communities with numerous benefits, the positive impacts resulting with greenway assimilation may not be equally distributed to communities of color and their residents. Research has shown that in urban settings communities of color and parks located within their boundaries are often avoided by White residents based on preconceived notions of neighborhood crime and disorder. This avoidance results in segregation and social isolation. Additionally, research has shown that the integration of a park or green space into a community of color may represent a threat to neighborhood culture and serve as a catalyst for neighborhood change. However, due to their contemporary nature, the effects of urban greenways on communities of color have been largely understudied and thus in need of additional research. The purpose of this study was to better understand how the integration of Chicago’s 606, an urban greenway on the city’s northwest side, into the Puerto Rican neighborhood of Humboldt Park was altering the social and structural environments in and around the community. In examining these components, the study highlights and provides insight for city leaders and park officials looking to assimilate similar corridors into their cityscape. This mixed method study included quantitative and qualitative approaches to assess use patterns and the experiences of trail users and neighborhood residents. Findings indicate that urban greenways may present a paradox for the neighborhoods in which they are integrated. The 606 had utility in lowering crime, increasing access for minority residents, and providing a safe space for both active and passive recreation. However, it also demonstrated that stigma associated with minorities and the spaces they occupy, in this case Humboldt Park, had the ability to perpetuate exclusionary practices, resource disparities, and sustain inequities between communities. The study also found that The 606 represented a threat to the Humboldt Park community, providing an entry point for White newcomers and an instrument for developers to accelerate green gentrification. This study fills an existing research gap related to urban greenways and their relationship with urban communities. While the study demonstrated that urban greenways may benefit communities of color, it also showed that these benefits may be inequitable and terse. As the popularity for parks and greenways of this sort increases, more research is needed to better understand the positive and negative impacts on proximate environments

Delimited Persistent Stochastic Non-Interference

Non-Interference is an information flow security property which aims to protect confidential data by ensuring the complete absence of any information flow from high level entities to low level ones. However, this requirement is too demanding when dealing with real applications: indeed, no real policy ever guarantees a total absence of information flow. In order to deal with real applications, it is often necessary to allow mechanisms for downgrading or declassifying information such as information filters and channel control. In this paper we generalize the notion of Persistent Stochastic Non-Interference (PSNI) in order to allow information to flow from a higher to a lower security level through a downgrader. We introduce the notion of Delimited Persistent Stochastic Non-Interference (D_PSNI) and provide two characterizations of it, one expressed in terms of bisimulation-like equivalence checks and another one formulated through unwinding conditions. Then we prove some compositionality properties. Finally, we present a decision algorithm and discuss its complexity