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Trust Management Systems in P2P Networks
Novotný, Miroslav ; Zavoral, Filip (advisor) ; Janeček, Jan (referee) ; Fujita, Satoshi (referee)
The architecture of certain class of services, such as distributed computing, distributed storages or content delivering networks shifts from the traditional client-server model to more scalable and robust peer to peer networks. Providing proper protection to such complex, open and anonymous systems is very complicated. Malicious peers can cooperate and develop sophisticated strategies to bypass existing security mechanisms. Recently, many trust management systems for P2P networks have been proposed. However, their effectiveness is usually tested only against simple malicious strategies. Moreover, a complex comparison of resistance of a particular method is missing. In this thesis, we (1) propose a new trust management system called BubbleTrust and (2) develop a simulation framework for testing trust management systems against various malicious strategies. Our simulation framework defines several criteria which determine the success of each malicious strategy in the network with a given system. We present results of four trust management systems that represent main contemporary approaches and BubbleTrust.
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Trust Management Systems in P2P Networks
Novotný, Miroslav ; Zavoral, Filip (advisor) ; Janeček, Jan (referee) ; Fujita, Satoshi (referee)
The architecture of certain class of services, such as distributed computing, distributed storages or content delivering networks shifts from the traditional client-server model to more scalable and robust peer to peer networks. Providing proper protection to such complex, open and anonymous systems is very complicated. Malicious peers can cooperate and develop sophisticated strategies to bypass existing security mechanisms. Recently, many trust management systems for P2P networks have been proposed. However, their effectiveness is usually tested only against simple malicious strategies. Moreover, a complex comparison of resistance of a particular method is missing. In this thesis, we (1) propose a new trust management system called BubbleTrust and (2) develop a simulation framework for testing trust management systems against various malicious strategies. Our simulation framework defines several criteria which determine the success of each malicious strategy in the network with a given system. We present results of four trust management systems that represent main contemporary approaches and BubbleTrust.
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Analysis and implementation of application for digital currency Bitcoin
DRDÁK, František
The thesis is focused on the topic of virtual cryptocurrency Bitcoin. The theoretical part is divided into several chapters. First of all, there is a chapter containing basic information about the currency's history, its development to the present, as well as principles of operation of this currency. Because it is a currency based on cryptographic principles next chapter summarizing cryptographic techniques, which is necessary to know for subsequent analysis of this currency. In other parts is elaborated a detailed analysis of the principles of Bitcoin. The main point of this analysis is a system of transactions, decentralized history, then joining the transactions into blocks and in the end creating blockchain. It also explains the principle of P2P networks. The practical part of this work focuses on the analysis and design of payment applications for mobile devices. There used open-source libraries such BitcoinJ. The application is developed in Java programming language with plugin for portable devices, which work under the operating system Android. For the purposes of analysis and design of graphical user interface is used UML diagrams. The specification of the UML diagrams was utilized by freely available graphics software and the result is also included in this work.
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