Peer-to-peer network applications has been a tremendous success among end users and has therefore received much attention in academia and industry, as have illegal public file sharing in media. However, private peer-to-peer file sharing between family, friends and co-workers have attracted little interest from the research community. Existing approaches also limit the users by not allowing for native interaction with userspace applications. In this paper we ex- -plore how private file sharing can be made safe, fast and scalable without constraining the users in this aspect. We demonstrate the concept of a private file sharing application utilizing a decentralized peer-to-peer network overlay by creating a prototype with extreme program- ming as methodology. To maximize the freedom of users the network is accessed through a virtual file-system interface. The prototype proves this to be a valid approach and we hope readers can use this paper as a platform for further developments in this area. / Fildelningsapplikationer som använder peer-to-peer teknik har varit en enorm framgång blandslutanvändare och har därmed erhållit mycket uppmärksamhet från akademi och indus- tri, liksom olaglig fildelning fått inom media. Däremot har inte privat fildelning mellan vän- ner, arbetskamrater och kollegor tilldelats samma uppmärksamhet från forskningssamfundet. Nuvarande tillämpningar begränsar användaren genom att inte tillåta naturlig interaktion med användarapplikationer. I denna uppsats utforskar vi hur privat fildelning kan göras snabb, skalbar och säker utan att begränsa användaren ur den aspekten. Vi demonstrerar ett koncept- för privat fildelning som nyttjar decentraliserad peer-to-peer arkitektur m.h.a en prototyp som tagits fram med extreme programming som metodologi. För att maximera användarnas frihet nyttjas ett virtuellt filsystem som gränssnitt. Prototypen visar att vår tillämpning fungerar i praktiken och vi hoppas att läsaren kan använda vårt arbete som en plattform för fortsatt utveckling inom detta område.

Commercial provisioning of file synchronization services (FSS) relies entirely on protocols that utilize a remote central server that is often located in the cloud to host important files. Updates at user computers are propagated to the central server and from the central server to other sources in need of such updates. Therefore, a synchronization operation between two computers located on the same network often results in file data transmission to and from this local network at least twice. This introduces an unnecessary bandwidth usage on a user’s local network and has become an issue, especially since there is an increase in the demands for internet resources. This thesis work presents a new file synchronization protocol towards FSS known as LAPSync (location-aware protocol for remote file synchronization). This paper also proposes a hierarchical synchronization mechanism by utilizing LAPSync. Our proposed solution relies on the ability of LAPSync clients to acquire knowledge about the location of clients participating in the synchronization operation to construct a hierarchical synchronization path. Finally, we implement our protocol into a prototype and conduct experiments to compare with drop-box (a popular file synchronization service). The results obtained show that LAPSync offers a reduction in bandwidth usage when the files to be synchronized exist on the same local network

This master's thesis deals with analysis and implementation of methods for BitTorrent monitoring focusing on the Mainline DHT protocol. The aim of the thesis was to create a system, that will be looking for BitTorrent peers that participe in the illegal file distribution. Another task of the system was to collect and analyze data for counting size of the BitTorrent network. That was achieved by taking over of existing method. The system was designed and implemented as a module for monitoring of cybernetic crime. It also defines an interface for storing and sharing data, that provides data evaluation, easy data manipulation and serves for possible future extensions.

[pt] Em uma série de aplicações, os pontos de dados podem ser representados como distribuições de probabilidade. Por exemplo, os documentos podem ser representados como modelos de tópicos, as imagens podem ser representadas como histogramas e também a música pode ser representada como uma distribuição de probabilidade. Neste trabalho, abordamos o problema do Vizinho Próximo Aproximado onde os pontos são distribuições de probabilidade e a função de distância é a divergência de Kullback-Leibler (KL). Mostramos como acelerar as estruturas de dados existentes, como a Bregman Ball Tree, em teoria, colocando a divergência KL como um produto interno. No lado prático, investigamos o uso de duas técnicas de indexação muito populares: Índice Invertido e Locality Sensitive Hashing. Os experimentos realizados em 6 conjuntos de dados do mundo real mostraram que o Índice Invertido é melhor do que LSH e Bregman Ball Tree, em termos de consultas por segundo e precisão. / [en] In a number of applications, data points can be represented as probability distributions. For instance, documents can be represented as topic models, images can be represented as histograms and also music can be represented as a probability distribution. In this work, we address the problem of the Approximate Nearest Neighbor where the points are probability distributions and the distance function is the Kullback-Leibler (KL) divergence. We show how to accelerate existing data structures such as the Bregman Ball Tree, by posing the KL divergence as an inner product embedding. On the practical side we investigated the use of two, very popular, indexing techniques: Inverted Index and Locality Sensitive Hashing. Experiments performed on 6 real world data-sets showed the Inverted Index performs better than LSH and Bregman Ball Tree, in terms of queries per second and precision.

This thesis brings a reader an overview about historical and modern world of cryptographic methods, as well evaluates actual state of cryptographic algorithm progressions, which are used in applications nowadays. The aim of the work describes common symmetric, asymmetric encryption methods, cryptographic hash functions and as well pseudorandom number generators, authentication protocols and protocols for building VPNs. This document also shows the basics of the successful modern cryptanalysis and reveals algorithms that shouldn't be used and which algorithms are vulnerable. The reader will be also recommended an overview of cryptographic algorithms that are expected to stay safe in the future.

This dissertation thesis attends to problems of electronic registry for VUT. It deals with the principal of electronic registry functioning, electronic signature and it compares offer of the commercial registries. It goes in for the proposal and implementation of the electronic registry for VUT. Since the using of the e- registry on all public service Office was legalized the people can avoid long queues and the employees are avoided from the stress before dead lines. By the communication through the electronic registry is very important the electronical signature. It is almost a full-valued and lawful alternative to the physical signature. For its safety and utility this system employes asymmetric codes and hash algorithm. Presently in many states, where the electronical signature is legalized it is used together with standard X 509 which defines the format of certificates, organization and action of certification authorities. The certification autority ensures safe connection of the person and general key for using of the electronical signature.

Výzkum prezentovaný v této práci je zaměřen na evoluční optimalizaci vybraných komponent síťových aplikací určených pro monitorovací systémy vysokorychlostních sítí. Práce začíná studiem současných monitorovacích systémů. Jako experimentální platforma byl zvolen systém SDM (Software Defined Monitoring). Detailně bylo analyzováno zpracování síťového provozu, protože tvoří důležitou součást všech monitorovacích systémů. Jako demonstrační komponenty pro aplikaci optimálních technik navržených v této práci byly zvoleny klasifikátor aplikačních protokolů a hashovací funkce pro síťové toky. Evoluční algoritmy byly zkoumány s ohledem nejen na optimalizaci kvality zpracování dat danou síťovou komponentou, ale i na čas potřebný pro výpočet dané komponenty. Byly zkoumány jednokriteriální i vícekriteriální varianty evolučních algoritmů.     Byl navržen nový přístup ke klasifikaci aplikačních protokolů. Přesná i aproximativní verze klasifikátoru byla optimalizována pomocí CGP (Kartézské Genetické Programování). Bylo dosaženo výrazné redukce zdrojů a zpoždění v FPGA (Programovatelné Logické Pole) oproti neoptimalizované verzi. Speciální síťové hashovací funkce byly navrženy pomocí paralelní verze LGP (Lineární Genetické Programování). Tyto hashovací funkce vykazují lepší funkcionalitu oproti moderním hashovacím funkcím. S využitím vícekriteriální optimalizace byly vylepšeny výsledky původní jednokriteriální verze LGP. Paralelní zřetězené verze hashovacích funkcí byly implementovány v FPGA a vyhodnoceny za účelem hashování síťových toků. Nová rekonfigurovatelná hashovací funkce byla navržena jako kombinace vybraných hashovacích funkcí.  Velmi konkurenceschopná obecná hashovací funkce byla rovněž navržena pomocí multikriteriální verze LGP a její funkčnosti byla ověřena na reálných datových sadách v provedených studiích. Vícekriteriální přístup produkuje mírně lepší řešení než jednokriteriální LGP. Také se potvrdilo, že obecné implementace LGP a CGP jsou použitelné pro automatizovaný návrh a optimalizaci vybraných síťových komponent. Je však důležité zvládnout vícekriteriální povahu problému a urychlit časově kritické operace GP

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Tendering is a method for entering into a sales contract. Numerous electronic tendering systems have been established with the intent of improving the efficiency of the tendering process. Although providing adequate security services is a desired feature in an e-tendering system, current e-tendering systems are usually designed with little consideration of security and legal compliance. This research focuses on designing secure protocols for e-tendering systems. It involves developing methodologies for establishing security requirements, constructing security protocols and using formal methods in protocol security verification. The implication is that it may prove suitable for developing secure protocols in other electronic business domains. In depth investigations are conducted into a range of issues in relation to establishing generic security requirements for e-tendering systems. The outcomes are presented in a form of basic and advanced security requirements for e-tendering process. This analysis shows that advanced security services are required to secure e-tender negotiation integrity and the submission process. Two generic issues discovered in the course of this research, functional difference and functional limitations, are fundamental in constructing secure protocols for tender negotiation and submission processes. Functional difference identification derives advanced security requirements. Functional limitation assessment defines how the logic of generic security mechanisms should be constructed. These principles form a proactive analysis applied prior to the construction of security protocols. Security protocols have been successfully constructed using generic cryptographic security mechanisms. These protocols are secure e-tender negotiation integrity protocol suite, and secure e-tender submission protocols. Their security has been verified progressively during the design. Verification results show that protocols are secure against common threat scenarios. The primary contribution of this stage are the procedures developed for the complex e-business protocol analysis using formal methods. The research shows that proactive analysis has made this formal security verification possible and practical for complex protocols. These primary outcomes have raised awareness of security issues in e-tendering. The security solutions proposed in the protocol format are the first in e-tendering with verifiable security against common threat scenarios, and which are also practical for implementation. The procedures developed for securing the e-tendering process are generic and can be applied to other business domains. The study has made improvements in: establishing adequate security for a business process; applying proactive analysis prior to secure protocol construction; and verifying security of complex e-business protocols using tool aided formal methods.

This master's thesis deals with design of security infrastructure for electronic archive. In theoretical part is disscus about technical resources which are based on security services and protocols and methods which are used for protection. On basics of theoretical part is designed model of security infrastructure and it is built in laboratory. Model of security infrastructure is based on Open Source Software and as safety storages for private user authentication data are used cryptographic USB tokens. This master's thesis includes design and construction of real infrastructure of secured electronic archive. In each part of master's thesis is put main emphases on security and clear explanation from the beginning of desing of model of security infrastructure for electronic archive to finish of construction.