Advances in wireless networking technology have engendered a new paradigm of computing, called mobile computing; in which users carrying portable devices have access to a shared infrastructure independent of their physical location. Mobile computing has matured rapidly as a field of computer science. In environments of mobile computing, the mobility and disconnection of portable computing devices introduce many new challenging problems that have never been encountered in conventional computer networks. New research issues combine different areas of computer science: networking, operating systems, data and knowledge management, and databases. This thesis studies data and knowledge transaction in mobile environments. To study transaction processing at the fundamental and theoretical level in mobile environments, a range of classical notions and protocols of transaction processing are rechecked and redefined in this thesis, and form the foundation for studying transaction processing in mobile environments. A criterion for mobile serial history is given and two new concurrency theorems are proved in mobile environments. In addition to data transaction, this thesis explores knowledge transaction in mobile environments. To study knowledge transaction in mobile environments this thesis presents and formalizes a knowledge transaction language and model for use in mobile computing environments. The thesis further formalizes a framework/model for a mobile logic programming multi-agent system which can be used to study knowledge transaction in multi-agent systems in mobile environments and is a very early effort towards a formal study of knowledge base and intelligent agents in mobile environments. This work provides a foundation for the formal specification and development of real-world mobile software systems, in the same way as traditional software systems have developed. / Doctor of Philosophy (PhD) (Science)

This thesis examines the use of adaptive user interface elements on a mobile phone and presents two adaptive user interface approaches. The approaches attempt to increase the efficiency with which a user interacts with a mobile phone, while ensuring the interface remains predictable to a user. ¶ An adaptive user interface approach is presented that predicts the menu item a user will select. When a menu is opened, the predicted menu item is highlighted instead of the top-most menu item. The aim is to maintain the layout of the menu and to save the user from performing scrolling key presses. A machine learning approach is used to accomplish the prediction task. However, learning in the mobile phone environment produces several difficulties. These are limited availability of training examples, concept drift and limited computational resources. A novel learning approach is presented that addresses these difficulties. This learning approach addresses limited training examples and limited computational resources by employing a highly restricted hypothesis space. Furthermore, the approach addresses concept drift by determining the hypothesis that has been consistent for the longest run of training examples into the past. Under certain concept drift restrictions, an analysis of this approach shows it to be superior to approaches that use a fixed window of training examples. An experimental evaluation on data collected from several users interacting with a mobile phone was used to assess this learning approach in practice. The results of this evaluation are reported in terms of the average number of key presses saved. The benefit of menu-item prediction can clearly be seen, with savings of up to three key presses on every menu interaction. ¶ An extension of the menu-item prediction approach is presented that removes the need to manually specify a restricted hypothesis space. The approach uses a decision-tree learner to generate hypotheses online and uses the minimum description length principle to identify the occurrence of concept shifts. The identification of concept shifts is used to guide the hypothesis generation process. The approach is compared with the original menu-item prediction approach in which hypotheses are manually specified. Experimental results using the same datasets are reported. ¶ Another adaptive user interface approach is presented that induces shortcuts on a mobile phone interface. The approach is based on identifying shortcuts in the form of macros, which can automate a sequence of actions. A means of specifying relevant action sequences is presented, together with several learning approaches for predicting which shortcut to present to a user. A small subset of the possible shortcuts on a mobile phone was considered. This subset consisted of shortcuts that automated the actions of making a phone call or sending a text message. The results of an experimental evaluation of the shortcut prediction approaches are presented. The shortcut prediction process was evaluated in terms of predictive accuracy and stability, where stability was defined as the rate at which predicted shortcuts changed over time. The importance of stability is discussed, and is used to question the advantages of using sophisticated learning approaches for achieving adaptive user interfaces on mobile phones. Finally, several methods for combining accuracy and stability measures are presented, and the learning approaches are compared with these methods.

Using a Key escrow agent in conjunction with Voice over IP (VoIP) communication ensures that law enforcements agencies (LEAs) can retrieve the session key used to encrypt data between two users in a VoIP session. However, the use of a single escrow agent has some drawbacks. A fraudulent request by an evil employee from the LEA can lead to improper disclosure of a session key. After the escrow agent reveals the key this evil person could fabricate data according to his/her needs and encrypt it again (using the correct session key). In this situation the persons involved in the communication session can be accused of crimes that he or she or they never committed. The problems with a single escrow agent becomes even more critical as a failure of the escrow agent can delay or even make it impossible to reveal the session key, thus the escrow agent might not be able to comply with a lawful court order or comply with their escrow agreement in the case of data being released according to this agreement (for example for disaster recovery).This thesis project focused on improving the accessibility and reliability of escrow agents, while providing good security. One such method is based on dividing the session key into m chunks and escrowing the chunks with m escrow agents. Using threshold cryptography the key can be regenerated by gathering any n-out-of-m chunks. The value of m and n may differ according to the role of the user. For a highly sophisticated session, the user might define a higher value for m and n for improved, availability, reliability, and security. For a less confidential or less important session (call), the value of m and n might be smaller. The thesis examines the increased availability and increased reliability made possible by using multiple escrow agents.

GSM and UMTS technologies have already gained a huge market penetrationresulting in millions of customers. Machine-to-Machine (M2M) Communicationis promising to be the next big technology that is going to hit themass market with numerous essential services. Telemetry systems, whichwere thought once as the domain of big industrial companies, are now beingavailable to larger and wider customers because of the advances in M2Mcommunication. Thanks to mobile technologies, millions of small handhelddevices are now available in the mass market which can be used to communicatereal time information to the customers. Telenor Objects (a smallbusiness unit of Telenor Group) has defined a new Connected Object Operatingsystem (COOS) which aims to provide a common platform for thedevices to communicate real time data and to provide value added servicesto the customers. COOS is a modular and flexible platform, and includes aplugin framework offered to device and service developers for easy connectingservices and devices to the platform. The current version of COOS pluginframework is based on Java Standard Edition and OSGI, with some supportfor development on J2ME. This thesis research work aims to provide a briefoverview of the Connected Object concept and the COOS platform architecture.The main goal of this thesis is to design a small footprint version ofthe COOS plugin framework for Windows-based handheld devices. It willalso provide a state-of- the art study on mobile device programming focusingon Windows-based services. This thesis research can serve as a startingdocument to provide a full functioning plugin framework for Windows-baseddevices and services.

Enterprise level software development using traditional software engineeringapproaches with third-generation programming languages is becoming morechallenging and cumbersome task with the increased complexity of products,shortened development cycles and heightened expectations of quality. MDD(Model Driven Development) has been counting as an exciting and magicaldevelopment approach in the software industry from several years. The ideabehind MDD is the separation of business logic of a system from its implementationdetails expressing problem domain using models. This separation andmodeling of problem domain simplify the process of system design as well asincrease the longevity of products as new technologies can be adopted easily.With appropriate tool support, MDD shortens the software development lifecycle drastically by automating a significant portion of development steps.MDA (Model Driven Architecture) is a framework launched by OMG (ObjectManagement Group) to support MDD. SPACE is an engineering methodfor rapid creation of services, developed at NTNU (Norwegian University ofScience and Technology) which follows MDA framework. Arctis and Ramsesare tool suits, also developed at NTNU to support SPACE method. Severalsolutions have been developed on Arctis tool suit covering several domainslike mobile services, embedded systems, home automation, trust managementand web services.This thesis presents a case study on the web application domain with Arctis,where the underlying technologies are AJAX (asynchronous JavaScriptand XML), GWT (Google Web Toolkit) framework and Java Servlet. Inorder to do that, this thesis contributes building up some reusable buildingblocks with Arctis tool suit. This thesis also describes a use case scenario touse those building blocks. This thesis work tries to implement the specifiedsystem and evaluates the resulting work.

Each day, anti-virus companies receive large quantities of potentially harmful executables. Many of the malicious samples among these executables are variations of earlier encountered malware, created by their authors to evade pattern-based detection. Consequently, robust detection approaches are required, capable of recognizing similar samples automatically.In this thesis, malware detection through call graphs is studied. In a call graph, the functions of a binary executable are represented as vertices, and the calls between those functions as edges. By representing malware samples as call graphs, it is possible to derive and detect structural similarities between multiple samples. The latter can be used to implement generic malware detection schemes, which can proactively detect existing versions of the malware, as well as future releases with similar characteristics.To compare call graphs mutually, we compute pairwise graph similarity scores via graphmatchings which minimize an objective function known as the Graph Edit Distance. Finding exact graph matchings is intractable for large call graph instances. Hence we investigate several efficient approximation algorithms. Next, to facilitate the discovery of similar malware samples, we employ several clustering algorithms, including variations on k-medoids clustering and DBSCAN clustering algorithms. Clustering experiments are conducted on a collection of real malware samples, and the results are evaluated against manual classifications provided by virus analysts from F-Secure Corporation. Experiments show that it is indeed possible to accurately detect malware families using the DBSCAN clustering algorithm. Based on our results, we anticipate that in the future it is possible to use call graphs to analyse the emergence of new malware families, and ultimately to automate implementinggeneric protection schemes for malware families.

During the last decades, Internet has evolved from host-centric toinformation-centric in the sense that it is information and data what matters,regardless of where it is located. Meanwhile, Internet's architecturestill remains the same as it was in its origins and still focuses on host-tohostcommunication, putting too much emphasis on the "where" ratherthan putting it on the "what".Original Internet's architecture also introduces several security aws suchas DoS and DDoS, spoong and spam, and other non-security relatedproblems such as availability or location dependence related issues. Inorder to address these issues, several new architectures and protocols havebeen proposed. Some of them aim at redesigning totally the architecture ofInternet from scratch, while others aim at improving it without redesigningit totally.The aim of this Master Thesis is to analyze these new protocols and architecturesfrom a security point of view in order to determine whether thesecurity claims made are true or not. The security analysis is made basedon RFCs, technical papers and project deliverables. The results obtainedhave uncovered some security issues in several of the new protocols andarchitectures and have provided some insight into further improving them.

Hand held mobile devices are widely used today primarily due to their rich functionality and the ease of portability. However, the battery life of these devices is very limited and deploying resource hungry applications such as streaming on these mobile devices is a challenging task. It is extremely important to maximize the efficient use of the contained resources on these devices especially when they participate in a mobile ad hoc network. The optimization can occur in any layer of the OSI stack, however, this thesis work focuses only on the routing protocols used in the network layer. In this thesis work we have been able to evaluate the Energy Efficiency of the four most widely used MANET routing protocols (AODV, OLSR, DSDV and DSR) in terms of their energy consumption and performance. The initial phase of the work was carried out using the Network Simulator 2(NS2) tool and later the observations were done on a real world MANET testbed. The influence of several external factors on the performance and energy consumption are also taken into consideration while performing the simulations and experiments. The results obtained from our observations provide both qualitative and quantitative analysis of the routing protocols. Furthermore, it also highlights how the behaviour of the protocols are sometimes highly unpredictable, yielding results that we may not expect.

Like conventional networks, security is also a big concern in wireless sensor networks. However, security in this type of networks faces not only typical but also new challenges. Constrained devices, changing topology or susceptibility to unprecedented security threats such as node capture and node compromise has refrained developers from applying conventional security solutions into wireless sensor networks. Hence, developing security solutions for wireless sensor networks not only requires well security analysis but also offers a low power and processing consuming.In this thesis, we implemented security solution targeting IRIS sensor motes. In our implementation, a public key-based key exchange is used to establish shared secret keys between sensor nodes. These secret keys are used to provide authenticity, integrity and freshness for transmission data. Our implementation ensures the flexibility in integrating our solution with available TinyOS operating system. Additionally, the thesis work also focuses on evaluating the performance in wireless sensor networks both in memory and energy consuming.

Hybrid optical packet/circuit switched networking architectures are increasingly becoming an interesting research field. They integrate and combine the high resource utilization of statistically multiplexed packet switched networks with the low processing requirements and guaranteed quality of service provided by circuit switched networks. The aim of this thesis is to integrate the OpMiGua hybrid optical network with Ethernet. Specifically, the work is focused on the compatibility of the Ethernet’s loop-free topology protocols with the redundant multiple traffic service paths of OpMiGua. We analyse the problems and limitations imposed on the network architecture and propose our topology solution called the SM chain-connectivity. The analysis and the proposed schemes are verified based on results obtained from simulations. Furthermore, we design an integrated logical OpMiGua node that relies on an Ethernet switch instead of the Optical Packet Switch for the Statistically Multiplexed traffic. To date, to our knowledge there are no studies analysing the compatibility of Ethernet and its protection mechanisms in a hybrid optical network. This is the first work addressing the use of Ethernet in OpMiGua.