by Lau Wai Kwong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 99-102). / Abstract --- p.ii / Acknowledgements --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Limitations of the Mobile Computing Environments --- p.2 / Chapter 1.2 --- Applications of Transaction Replication in Mobile Environments --- p.5 / Chapter 1.3 --- Motivation for Transaction Replication in Mobile Environments --- p.5 / Chapter 1.4 --- Major Simulation Results --- p.6 / Chapter 1.5 --- Roadmap to the Thesis --- p.7 / Chapter 2 --- Previous and Related Research --- p.8 / Chapter 2.1 --- File Systems --- p.8 / Chapter 2.1.1 --- Management of Replicated Files --- p.8 / Chapter 2.1.2 --- Disconnected Operations --- p.10 / Chapter 2.2 --- Database Management --- p.12 / Chapter 2.2.1 --- Data Replication Schemes --- p.12 / Chapter 2.2.2 --- Cache Invalidation and Query Processing --- p.15 / Chapter 2.2.3 --- Transaction Management in Mobile Environments --- p.17 / Chapter 3 --- System Model and Assumptions --- p.21 / Chapter 3.1 --- System Architecture --- p.21 / Chapter 3.2 --- Transaction and Data Model --- p.23 / Chapter 3.3 --- One-copy Serializability --- p.25 / Chapter 3.4 --- Assumptions --- p.27 / Chapter 4 --- Transaction Replication in a Mobile Environment --- p.29 / Chapter 4.1 --- Read-only Public Transactions --- p.30 / Chapter 4.1.1 --- Data Broadcasting --- p.31 / Chapter 4.1.2 --- Cache Update --- p.33 / Chapter 4.1.3 --- Cache Miss --- p.36 / Chapter 4.1.4 --- Execution of Read-only Public Transactions --- p.37 / Chapter 4.2 --- R/W Public Transactions --- p.39 / Chapter 4.3 --- Correctness Argument --- p.41 / Chapter 4.3.1 --- Correctness Proof --- p.43 / Chapter 4.4 --- Extension to Support Partition Failures --- p.47 / Chapter 5 --- Design and Implementation of the Simulation --- p.49 / Chapter 5.1 --- CSIM Language --- p.49 / Chapter 5.2 --- Simulation Components --- p.50 / Chapter 5.2.1 --- Fixed Network --- p.50 / Chapter 5.2.2 --- Mobile Host --- p.50 / Chapter 5.2.3 --- Wireless Channel --- p.51 / Chapter 5.2.4 --- Database and Transactions --- p.52 / Chapter 5.3 --- A Lock-based Scheme --- p.53 / Chapter 5.4 --- Graphing ...........、 --- p.54 / Chapter 6 --- Results and Analysis --- p.55 / Chapter 6.1 --- Results Dissection --- p.55 / Chapter 6.2 --- Performance of the Scheme --- p.56 / Chapter 6.2.1 --- Parameters Setting --- p.56 / Chapter 6.2.2 --- Experiments and Results --- p.59 / Chapter 6.3 --- Comparison with the Lock-based Scheme --- p.78 / Chapter 6.3.1 --- Parameters Setting --- p.79 / Chapter 6.3.2 --- Experiments and Results --- p.80 / Chapter 7 --- Conclusions and Future Work --- p.93 / Chapter 7.1 --- Conclusions --- p.93 / Chapter 7.2 --- Future Work --- p.94 / Chapter A --- Implementation Details --- p.96 / Bibliography --- p.99

The need for information anywhere and at any time has been the driving force for the increasing growth in mobile networks and devices. The field of mobile computing is the merger of advances in computing and communications with the aim of providing seamless and ubiquitous computing environment for mobile users. Whereas notebook computers and personal digital assistants (PDAs) are self-contained, networked computing constitutes a new paradigm of computing that is revolutionizing the way computers are used. Mobile networking greatly enhances the utility of carrying a computing device. It provides mobile users with versatile communication to other people and expedient notification of important events, yet with much more flexibility than cellular telephones and pagers. It also permits continuous access to services and resources of the traditional land-based wired networks. This combination of networking and mobility will engender new applications and services, such as collaborative software to support impromptu meetings, electronic bulletin boards that adapt to the contents according to the participants present, self adjusting lighting and heating, and navigation software to guide users in unfamiliar places and tours. To support mobility in the Internet, the Internet Protocol (IP) has been extended to support mobility. Also at the same time, there is also a growing trend for these IP based networks to operate in an infrastructureless environment called mobile ad-hoc networks. However, the proliferation of such mobile networks depends on a multitude of factors, with trustworthiness being one of the primary challenges to be met. The objective of this dissertation is to address the issues involved in the design of security services for Mobile IP and ad-hoc networks. Extensions to IP based networks (both wired and infrastructureless networks) to facilitate mobility have not been designed keeping security in mind. However adequate security features are basic requirements for the continued functioning of mobile networks. Clearly the problem is so broad that there is no way to devise a general solution We aim to address most of these wide- ranging problems and in the process initiate a practical approach to the development of an integrated security infrastructure for mobile networks. The intention is to seamlessly integrate these security services and mechanisms at the IP level within the mobile IP and ad-hoc networks. The provision of security services at the higher and lower layers and their interoperability with our proposed framework is outside the scope of this thesis / Doctor of Philosophy (PhD)

Thesis (M.S.)--University of Nevada, Reno, 2005. / "December 2005." Includes bibliographical references (leaves 49-55). Online version available on the World Wide Web.

Thesis (Doctoral)--Universität des Saarlandes, 2006. / Includes bibliographical references (p. 175-193) and index.

Security engineering is one of the important concerns during system development. It should be addressed throughout the whole system development process; however in many cases it is often dealt only during system development and maintenance. There are several security modeling languages (e.g, Misuse case, Secure Tropos) that help dealing with security risk management at the requirements stage. In this thesis, we are focusing on the modeling languages (e.g. Mal activity diagrams and SecureUML) that are used to design the system. More specifically we investigate how these languages support information systems security risks management (ISSRM). The outcome of this work is an alignment table between the Mal activity diagrams and SecureUML language constructs to the ISSRM domain model concepts. We ground our analysis and validate the received results on the number of illustrative examples. We hope that our results will help developers to understand how they can consider security risks at the system design stage. In addition we open the way for the interoperability between different modeling languages that are analysed using the same conceptual background, thus, potentially leading to the transformation between these modeling approaches.

GSM network capable of connecting to any operator providing SIP trunk has beenconstructed to serve as a target for controlled experiment on DoS attacks againstGSM. The usage of this network as a tool to perform DoS attack against mobilephones was also investigated and documented.Open source implementation of testing tool to check DoS resilience of any GSMbase station against RACH flood attack was developed as part of this thesis.Additionally, the analysis of the GSM flaws which opened the possibility for DoSattacks, and the analysis of potential countermeasures is presented.

Typical authentication systems provide a method to allow registered users access to protected resources after the user successfully authenticates. A user successfully authenticates by proving his or her valid identity if he or she is a registered user. During a typical authentication process, the authentication server can directly or indirectly learn the actual identity of the user who authenticates. However, the user might not want any one to know the actual identity of the user, while still able to authenticate. This problem of user's anonymous authentication is the focus of this thesis project. This thesis project provides a solution for user's anonymous authentication using Secure Multi-party Computation (SMPC). In SMPC, the user information is distributed among the authentication servers, using a secret sharing scheme, in such a way that none of the authentication server individually possesses all the information of a user. However, these authentication servers can validate the user using some SMPC arithmetic operations. This thesis project provides a model for anonymous authentication and couples this anonymous authentication system with the Open Authentication Protocol (OAuth) to allow the user access to protected resources on the server. The model is explained using UML collaborations and SDL state transition diagrams. A analysis of the model is provided to ensure the security of the proposed system. A skeleton of the proposed model is provided which needs to be completed with appropriate code to realize the functionalities. This thesis project also provides an implementation of a simplified prototype which represents the core of the proposed model for anonymous authentication.

Cloud Computing is a new computing model, and its security aspects require special considerations. New characteristics of the cloud model have introduced new security challenges, and made some of the existing security techniques incompatible. Moreover, existing cloud environments are closed, operated by commercial providers, and their security mechanisms are proprietary as well as confidential. In other words, there is not much chance of observing how a real cloud environment is working, and how their providers adapt security measures to the new model.Therefore, we have chosen an open source cloud platform to build our own cloud environment. The OpenStack cloud software met our requirements, but it was not mature enough. We have done a deep analysis of this platform, identified potential attack targets in it, and discuss impacts of a successful attack.In order to secure our environment, the National Institute of Standards and Technology (NIST) incident handling guideline has been applied to the cloud model, and corresponding actions for each phase has been performed. To complete our study, we have proposed a set of cloud specific approaches that fulfill the incident handling requirements. These approaches address challenges identified in the guideline adaptation process. Additionally, we have studied the feasibility and compatibility of each approach against our deployed environment.Additionally, we also have submitted a paper to IEEE CloudCom 2011 conference, based on my thesis. A draft version of the paper is included in Appendix A.

In recent years, technologies in the area of ubiquitous computing have experienced a great advancement. This has resulted in a wide-spread use of services in order to improve the quality of our daily life. For example, a person with a mobile device can use the services available in the ubiquitous computing environment to plan and execute his or her travel, to connect to family and friends, to perform his or her researches, even to manage his or her business. However, most of the services are dynamic in nature in terms of their availability, robustness and the mobility of the user. These services also appear impermeable to the end users i.e. the end users do not get to control and configure the services in a way so as to feel like programmers developing services to accomplish certain goals. We envisage that in such a context end users, with no programming knowledge, will have a hard time to find services of their choice and that it will be hard for these end users to derive substantial benefits from these services. Unguided automation is not the answer to this problem as a particular service suggested automatically by a dynamic composition mechanism may not be suitable for a specific user at a certain point of time and in a given context. On the other hand explicit specification of service instances will mean that the user will be bogged down with the problem of runtime optimization in a dynamic environment where several factors as indicated earlier determine the availability of the services having required functionality. In order to address this issue we introduce the notion of intelligent service composition where the end user will have a great degree of flexibility to define his or her own rules or conditions based on which an optimal composition will be made automatically from a set of collaborative services by runtime adaptation in a specific context and point in time. This is a step forward compared to the present dynamic composition mechanisms which do not facilitate end users defining their own conditions dictating the selection of specific service instance at runtime. We have developed this conceptual solution to bring end users towards adaptive use of services. We validated our conceptual solution through a scenario-based evaluation approach with an implementation of a proof-of-concept prototype.

Information-flow control is an important element in computer system security, and there has been significant work done in the field by Denning, Volpano, and others. However, most of the work deals with information-flow control inside a single monolithic application. Wide adoption of the Web service architecture and related technologies effectively solved the problem of universal standard of interconnection of independent systems into larger scale system, but largely ignored the problem of information-flow control. This thesis suggests an approach, which allows for information-flow control techniques of the decentralised label model to be applied to distributed loosely-coupled systems based on Web services. The resulting system design is compatible with existing Web service-based systems, and allows for integration of components that do not natively support information-flow control.