Improving the Secrecy of Distributed Storage Systems using Interference Alignment

Regenerating codes based on the approach of interference alignment for wireless interference channel achieve the cut-set bound for distributed storage systems. These codes provide data reliability, and perform efficient exact node repair when some node fails. Interference alignment as a concept is especially important to improve the repair efficiency of a failed node in a minimum storage regenerating (MSR) code. In addition it can improve the stored data security in presence of passive intruders. In this paper we construct a new code resilient against a threat model where a passive eavesdropper can access the data stored on a subset of nodes and the downloaded data during the repair process of a subset of failed nodes. We achieve an optimal secrecy capacity for the new explicit construction of MSR interference alignment code. Hence, we show that the eavesdropper obtains zero information from the original message stored across the distributed storage, and that we achieve a perfect secrecy.Comment: 20 pages, 3 figure

Modelling and simulation framework for reactive transport of organic contaminants in bed-sediments using a pure java object - oriented paradigm

Numerical modelling and simulation of organic contaminant reactive transport in the environment is being increasingly relied upon for a wide range of tasks associated with risk-based decision-making, such as prediction of contaminant profiles, optimisation of remediation methods, and monitoring of changes resulting from an implemented remediation scheme. The lack of integration of multiple mechanistic models to a single modelling framework, however, has prevented the field of reactive transport modelling in bed-sediments from developing a cohesive understanding of contaminant fate and behaviour in the aquatic sediment environment. This paper will investigate the problems involved in the model integration process, discuss modelling and software development approaches, and present preliminary results from use of CORETRANS, a predictive modelling framework that simulates 1-dimensional organic contaminant reaction and transport in bed-sediments

Policy enforcement in cloud computing

Cloud Computing is an emerging technology, providing attractive way of hosting and delivering services over the Internet. Many organizations and individuals are utilizing Cloud services to share information and collaborate with partners. However, Cloud provides abstraction over the underlying physical infrastructure to the customers, that raises information security concerns, while storing data in a virtualized environment without having physical access to it. Additionally, certain standards have been issued to provide interoperability between users and various distributed systems(including Cloud infrastructures), in a standardized way. However, implementation and interoperability issues still exist and introduce new challenges. This thesis explores the feasibility of securing data in a cloud context, using existing standards and specifications, while retaining the benefits of the Cloud. The thesis provides a view on increasing security concerns of moving to the cloud and sharing data over it. First, we define security and privacy requirements for the data stored in the Cloud. Based on these requirements, we propose the requirements for an access control system in the Cloud. Furthermore, we evaluate the existing work in the area of currently available access control systems and mechanisms for secure data sharing over the Cloud, mostly focusing on policy enforcement and access control characteristics. Moreover, we determine existing mechanisms and standards to implement secure data sharing and collaborative systems over the Cloud. We propose an architecture supporting secure data sharing over the untrusted Cloud environment, based on our findings. The architecture ensures policy based access control inside and outside Cloud, while allowing the benefits of Cloud Computing to be utilized. We discuss the components involved in the architecture and their design considerations. To validate the proposed architecture, we construct the proof of concept prototype. We present a novel approach for implementing policy based access control, by achieving interoperability between existing standards and addressing certain issues, while constructing the system prototype. Furthermore, we deploy our solution in the Cloud and perform the performance tests to evaluate the performance of the system. Finally, we perform a case study by utilizing our system in a real-life scenario. To do this we slightly tailor our solution to meet specific needs. Overall, this thesis provides a solid foundation for the policy enforcement and access control mechanisms in the Cloud-based systems and motivates further work within this field. Cloud Computing is an emerging technology, providing attractive way of hosting and delivering services over the Internet. Many organizations and individuals are utilizing Cloud services to share information and collaborate with partners. However, Cloud provides abstraction over the underlying physical infrastructure to the customers, that raises information security concerns, while storing data in a virtualized environment without having physical access to it. Additionally, certain standards have been issued to provide interoperability between users and various distributed systems(including Cloud infrastructures), in a standardized way. However, implementation and interoperability issues still exist and introduce new challenges. This thesis explores the feasibility of securing data in a cloud context, using existing standards and specifications, while retaining the benefits of the Cloud. The thesis provides a view on increasing security concerns of moving to the cloud and sharing data over it. First, we define security and privacy requirements for the data stored in the Cloud. Based on these requirements, we propose the requirements for an access control system in the Cloud. Furthermore, we evaluate the existing work in the area of currently available access control systems and mechanisms for secure data sharing over the Cloud, mostly focusing on policy enforcement and access control characteristics. Moreover, we determine existing mechanisms and standards to implement secure data sharing and collaborative systems over the Cloud. We propose an architecture supporting secure data sharing over the untrusted Cloud environment, based on our findings. The architecture ensures policy based access control inside and outside Cloud, while allowing the benefits of Cloud Computing to be utilized. We discuss the components involved in the architecture and their design considerations. To validate the proposed architecture, we construct the proof of concept prototype. We present a novel approach for implementing policy based access control, by achieving interoperability between existing standards and addressing certain issues, while constructing the system prototype. Furthermore, we deploy our solution in the Cloud and perform the performance tests to evaluate the performance of the system. Finally, we perform a case study by utilizing our system in a real-life scenario. To do this we slightly tailor our solution to meet specific needs. Overall, this thesis provides a solid foundation for the policy enforcement and access control mechanisms in the Cloud-based systems and motivates further work within this field