Suchergebnisse

A routing protocol known as Epidemic Routing has been proposed as a means to transmit information between nodes in partially connected mobile ad hoc networks (MANET's). Many different aspects of the Epidemic Routing protocol such as energy efficiency and message delivery latency have been examined in terms of military and scientific applica- tions. This research examines the adaptation of the Epidemic Routing protocol and its variants as a possible means of communicating in urban protest type environments where traditional means of technological communication are easily disrupted by malicious par- ties. With this application in mind, the Epidemic Routing protocol was evaluated in a series of simulations to show that it is surprisingly capable of efficiently disseminating in- formation in this type of situation and of withstanding tampering from malicious parties. Lastly the feasibility of adapting the Epidemic Routing protocol to a real world applica- tion both for the purpose of disseminating information in an urban protest environment and in general is examined given current technological limitations. The lack of a suitable wireless networking technology is identified as the primary deterrent in creating a real world adaptation of an Epidemic Routing protocol and the general requirements needed for a successful adaptation are outlined.

The purpose of this research is to determine the feasibility of using the header fields and header extensions of IPv6 packets to encode mission metadata into computer network streams. Specifically, this thesis seeks to answer several research questions addressing the performance of different packet header encoding methods, specifically which method provides the least end-to-end delay of a file transfer over a hypothetical network as well as which method produces the least amount of additional network overhead during its operation in the hypothetical network. The research questions are answered through a comprehensive literature review and with the use of several network performance calculations. Results are analyzed and a final recommendation is given for which method would best meet the stated need. Ultimately, this research highlights a new way of tracking and reporting to military leaders the status of operational missions and tasks should a network outage or degradation occur.

The Internet has emerged as one of the most important tools of communication. With around 4.5 billion active users as of July 2020, it provides people the opportunity to access a vast treasure trove of information and express their opinions online. How- ever, some countries consider the Internet as a critical communication medium and attempt to deploy network interference strategies. National governments, in particular, are notorious for their attempts to impose restrictions on online communication. Further, certain Internet service providers (ISPs) have been known to throttle specific applications and violate net neutrality principles. Alongside the proliferation of network interference and an increasing awareness of the security and privacy of users over the Internet, we have seen a rise in the usage of network traffic encryption technologies. However, even with encryption enabled, network interference is still possible due to the information leakage of the DNS and TLS protocols. To this end, a rich ecosystem of DNS/TLS improvements has come to light with the purpose of improving user privacy by obfuscating the domains a user visits. These protocols have the potential to render certain forms of censorship ineffective. In this dissertation, I will describe my contributions towards understanding net-work interference, including Internet censorship, as well as the throttling of specific network applications (traffic differentiation). I develop a network measurement platform that enables monitoring of network interference globally on an ongoing basis. I then focus on understanding the DNS censorship behavior of the Great Firewall of China (GFW) by leveraging remote network measurement techniques. Additionally, I investigate the prevalence of traffic differentiation practices and how they impact popular video streaming applications. I demonstrate that network interference is prevalent even with encryption enabled. This has led to the development of DNS and TLS improvements that aim to enhance user privacy and ...

Wireless Sensor Networks are becoming popular as a means of collecting data by military organisations, public utilities, motor vehicle manufacturers and security firms. Unfortunately, the devices on such networks are often insecure by default, which creates problems in terms of the confidentiality and integrity of data transmitted across such networks. This paper discusses attacks that were successful on a simple network consisting of nodes using the ZigBee protocol stack and proposes defences to thwart these attacks, thus leading to increased user confidence in the ability of organisations to provide secure and effective services. The outcomes were that it was possible to add false nodes to a test network and have these nodes accepted by the network. This was because the packet encryption available for the devices was disabled by default.

A growing number of secure group applications in both civilian and military domains is being deployed in WAHNs. A Wireless Ad-hoc Network (WARN) is a collection of autonomous nodes or terminals that communicate with each other by forming a multi-hop radio network and maintaining connectivity in a decentralized manner. A Mobile Ad-hoc Network (MANET) is a special type of WARN with mobile users. MANET nodes have limited communication, computational capabilities, and power. Wireless Sensor Networks (WSNs) are sensor networks with massive numbers of small, inexpensive devices pervasive throughout electrical and mechanical systems and ubiquitous throughout the environment that monitor and control most aspects of our physical world. In a WAHNs and WSNs with un-trusted nodes, nodes may falsify information, collude to disclose system keys, or even passively refuse to collaborate. Moreover, mobile adversaries might invade more than one node and try to reveal all system secret keys. Due to these special characteristics, key management is essential in securing such networks. Current protocols for secure group communications used in fixed networks tend to be inappropriate. The main objective of this research is to propose, design and evaluate a suitable key management approach for secure group communications to support WAHNs and WSNs applications. Key management is usually divided into key analysis, key assignment, key generation and key distribution. In this thesis, we tried to introduce key management schemes to provide secure group communications in both WAHNs and WSNs. Starting with WAHNs, we developed a key management scheme. A novel architecture for secure group communications was proposed. Our proposed scheme handles key distribution through Combinatorial Key Distribution Scheme (CKDS). We followed with key generation using Threshold-based Key Generation in WAHNs (TKGS). For key assignment, we proposed Combinatorial Key Assignment Scheme (CKAS), which assigns closer key strings to co-located nodes. We claim that our architecture can readily be populated with components to support objectives such as fault tolerance, full-distribution and scalability to mitigate WAHNs constraints. In our architecture, group management is integrated with multicast at the application layer. For key management in WSNs, we started with DCK, a modified scheme suitable for WSNs. In summary, the DCK achieves the following: (1) cluster leader nodes carry the major part of the key management overhead; (2) DCK consumes less than 50% of the energy consumed by SHELL in key management; (3) localizing key refreshment and handling node capture enhances the security by minimizing the amount of information known by each node about other portions of the network; and (4) since DCK does not involve the use of other clusters to maintain local cluster data, it scales better from a storage point of view with the network size represented by the number of clusters. We went further and proposed the use of key polynomials with DCK to enhance the resilience of multiple node capturing. Comparing our schemes to static and dynamic key management, our scheme was found to enhance network resilience at a smaller polynomial degree t and accordingly with less storage per node.

This research develops Code White, a hardware-implemented trusted execution mechanism for the Symbian mobile operating system. Code White combines a signed whitelist approach with the execution prevention technology offered by the ARM architecture. Testing shows that it prevents all untrusted user applications from executing while allowing all trusted applications to load and run. Performance testing in contrast with an unmodified Symbian system shows that the difference in load time increases linearly as the application file size increases. The predicted load time for an application with a one megabyte code section remains well below one second, ensuring uninterrupted experience for the user. Smartphones have proven to be invaluable to military, civic, and business users due in a large part to their ability to execute code just like any desktop computer can. While many useful applications have been developed for these users, numerous malicious programs have also surfaced. And while smartphones have desktop-like capabilities to execute software, they do not have the same resources to scan for malware. More efficient means, like Code White, which minimize resource usage are needed to protect the data and capabilities found in smartphones.

Tax evasion is a serious economic problem for many countries, as it can undermine the government's tax system and lead to an unfair business competition environment. Recent research has applied data analytics techniques to analyze and detect tax evasion behaviors of individual taxpayers. However, they have failed to support the analysis and exploration of the related party transaction tax evasion (RPTTE) behaviors (e.g., transfer pricing), where a group of taxpayers is involved. In this paper, we present TaxThemis, an interactive visual analytics system to help tax officers mine and explore suspicious tax evasion groups through analyzing heterogeneous tax-related data. A taxpayer network is constructed and fused with the respective trade network to detect suspicious RPTTE groups. Rich visualizations are designed to facilitate the exploration and investigation of suspicious transactions between related taxpayers with profit and topological data analysis. Specifically, we propose a calendar heatmap with a carefullydesigned encoding scheme to intuitively show the evidence of transferring revenue through related party transactions. We demonstrate the usefulness and effectiveness of TaxThemis through two case studies on real-world tax-related data and interviews with domain experts.

Military and industry are moving toward every device being network enabled and connected for reliable availability of communication and information. To make this type of system a reality, the devices must be capable of forming a network topology on their own in a dynamic environment to ensure that the correct information reaches a desired location and on-time. This research presents three contributions for solving highly dynamic (i.e. drastic change within the network) Multi-commodity Capacitated Network Design Problems (MCNDPs) resulting in a distributed multi-agent network design algorithm. The first contribution incorporates an Ant Colony Optimization (ACO) algorithm Ant Colony System (ACS) to solve the static MCNDP with weak constraints. Second, a new algorithm is developed and has the capability to dynamically adjust its exploration parameter of the solution space. This enhanced algorithm converges quickly and automatically adjusts to the dynamically changing network environment. Third, a distributed approach is created replacing the previous centralized solver. The distributed algorithm produces comparable results, but more importantly calculates the network topology in less than 20 percent of the computation time.

Military environments require highly dynamic mobile ad hoc networks (MANETs) to meet operational mission requirements. Decision makers rely on the timely delivery of critical battlefield information to make informed determinations quickly and as accurately as possible. However, traditional MANET routing protocols do not provide quality of service (QoS). Furthermore, they do not implement active controls to minimise the impact of network congestion. This study proposes the use of the information embedded in an air tasking order (ATO) during the planning phase of military missions to optimise the network performance. The trajectories of relevant nodes (airborne platforms) participating in the MANET can be forecasted by parsing key information contained in the ATO. Using this idea it is possible to optimise network routes to minimise edge overutilisation and increase network throughput. In onesimulated test case, there was a 25% improvement of network throughput, and 23% reduction on dropped packets. Using this technique, the authors can selectively preserve the QoS by establishing network controls that drop low-priority packets when necessary. The algorithm improves the overall MANET throughput while minimising the packets dropped due to network congestion.

The evolution of the Internet and AI technology has made it possible for the government and the businesses to keep track of their personal lives. GAFA continues to collect information unintended by the individuals. It is a threat that our privacy is violated in this way. In order to solute such problems, it is important to consider a mechanism that enables us to be peaceful lives while protecting privacy in the Internet society. This paper focuses on the consumption behavior on the Internet and addresses anonymity. We consider some network protocols that enable sustainable consensus by combining anonymity methods such as I2P and anonymity currency as anonymity protects our lives from the engineering , and its application and clarification. As a result, we could propose a new consensus protocol, Proof of Sacrifice.

The rapid advancement in technology and internet penetration have substantially increased the number of economic transactions conducted online. Platforms that connect economic agents play an important role in this digital economy. The unbridled proliferation of digital platforms calls for a closer examination of the factors that could affect the welfare of the increasing number of economic agents who participate in them. This dissertation examines the factors that could affect the welfare of agents using the setting of a crowdfunding platform where fundraisers develop campaigns to solicit funding from potential donors. These factors can be broadly categorized into three distinct groups: (1) campaign and its corresponding fundraiser characteristics, (2) other factors within the platform, and (3) other factors outside the platform. The first group of factors has been examined in a large number of studies. The second and third groups, which encompass factors external to the campaigns and fundraisers remain under-explored and therefore are the focus of this dissertation. The first essay in this dissertation explores a factor within the platform; how displaying certain campaigns more prominently on the platform affects the performance of other campaigns. Such selective prominent practice is often viewed negatively because it is perceived to place less prominent sellers at a disadvantage (Kramer & Schnurr, 2018). The findings from the first essay provide a counterpoint to this popular view by documenting a positive spill-over effect from an increase in the performance of the prominent campaigns. In particular, when the prominent campaigns perform well, market expansion occurs with more donors entering the platform, benefiting the less prominent campaigns. These findings mitigate the concern that non-neutral practices on digital platforms naturally lead to the rich getting richer and the poor getting poorer. The second essay explores a factor external to the platform; how public statements from a government official affect private donations to charitable crowdfunding campaigns. A clear pattern of ethnic homophily among fundraisers and donors, where Hispanic fundraisers receive disproportionately more donations from Hispanic donors, is observed in this setting. This pattern of homophily becomes stronger following statements from President Donald Trump. This essay documents how social media usage, particularly by a government official, can influence the dynamic within and across ethnic groups. In sum, the findings from the two essays help inform platform designers, policymakers, and government officials of the potential effects of their actions on the digital economy.