Description
In today’s technological world, there is no question that access to sensitive data must be
limited to authorized individuals to prevent data leaks and unauthorized tampering.
Traditional access control assumes that at the time of request, a final decision can be
made whether access to an object is allowed or not. In practice, this assumption is often
not applicable, as usage conditions can change over time. To meet this requirement,
usage control was introduced, which not only makes a usage decision at the time of
request, but continuously checks whether a usage can still be permitted. Unfortunately,
existing frameworks for enforcing usage control policies do not yet meet all the desired
requirements for real-world use cases. Some provide only a theoretical basis, others
lack the expressiveness to support important requirements or show weaknesses in
the complexity of policies. Furthermore, the frameworks often lack an administrative
model that specifies authority procedures.
The thesis investigates the extent to which use-case driven usage control requirements
can be modeled and enforced using temporal and first-order logic. The reason for this
is firstly that logic is a natural way to express policies, and secondly that it is assumed
to reduce the complexity of policies. In addition, an administrative model is presented
that implements administrative processes themselves as usage decision processes. For
this, usage control requirements, derived from selected use cases, are modeled in a
policy model that defines what should be enforced. This policy model is based on
the UCON ABC framework and its temporal logic rules, and is extended to support
dependencies between usages. The enforcement model and the implementation model
then deal with the question of how the policy model can be implemented. As it turns
out, all temporal properties of the policies can be implicitly represented by the control
flow, such that only first-order logic remains for decision-making. To demonstrate
the expressiveness and the usability of the framework, a Proof of Concept (PoC) is
implemented in Kotlin.
We observe that LUCE supports all the analyzed requirements, solves the problems of
existing usage control frameworks and reduces the complexity of policies.
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Thesis topic in co-operation with the Fraunhofer Institute for Applied and Integrated Security AISEC, Garching