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Specification and verification of confidentiality in software architectures

Ulu, Cemil
This dissertation addresses the confidentiality aspect of the information security problem from the viewpoint of the software architecture. It presents a new approach to secure system design in which the desired security properties, in particular, confidentiality, of the system are proven to hold at the architectural level. The architecture description language Wright is extended so that confidentiality authorizations can be specified. An architectural description in Wright/c, the extended language, assigns clearance to the ports of the components and treats security labels as a part of data type information. The security labels are declared along with clearance assignments in an access control lattice model, also expressed in Wright/c. This enables the static analysis of data flow over the architecture subject to confidentiality requirements as per Bell-LaPadula principles. An algorithm takes the Wright/c description and the lattice model as inputs, and checks if there is a potential violation of the Bell-LaPadula principles. The algorithm also detects excess privileges. A software tool, which features an XML-based front-end to the algorithm is constructed. Finally, the algorithm is analyzed for its soundness, completeness and computational complexity.