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Digital archive of theses discussed at the University of Pisa


Thesis etd-06142011-232420

Thesis type
Tesi di dottorato di ricerca
Thesis title
Access and Usage Control in Grid
Academic discipline
Course of study
tutor Dott. Martinelli, Fabio
  • Access Control
  • Globus
  • Grid
  • UCON
  • Usage Control
Graduation session start date
Grid is a computational environment where heterogeneous resources are virtualized and outsourced to multiple users across the Internet. The increasing popularity of the resources visualization is explained by the emerging suitability of such technology for automated execution of heavy parts of business and research processes. Efficient and flexible framework for the access and usage control over Grid resources is a prominent challenge.
The primary objective of this thesis is to design the novel access and usage control model providing the fine-grained and continuous control over computational Grid resources. The approach takes into account peculiarities of Grid: service-oriented architecture, long-lived interactions, heterogeneity and distribution of resources, openness and high dynamics.
We tackle the access and usage control problem in Grid by Usage CONtrol (UCON) model, which presents the continuity of control and mutability of authorization information used to make access decisions. Authorization information is formed by attributes of the resource requestor, the resource provider and the environment where the system operates. Our access and usage control model is considered on three levels of abstraction: policy, enforcement and implementation.
The policy level introduces security policies designed to specify the desired granularity of control: coarse-grained policies that manages access and usage of Grid services, and fine-grained policies that monitor the usage of underlying resources allocated for a particular Grid service instance. We introduce U-XACML and exploit POLPA policy languages to specify and formalize security policies. Next, the policy level presents attribute management models. Trust negotiations are applied to collect a set of attributes needed to produce access decisions. In case of mutable attributes, a risk-aware access and usage control model is given to approximate the continuous control and timely acquisition of fresh attribute values.
The enforcement level presents the architecture of the state-full reference monitor designed to enforce security policies on coarse- and fine-grained levels of control.
The implementation level presents a proof-of-concept realization of our access and usage control model in Globus Toolkit, the most widely used middleware to setup computational Grids.