The main aim of this thesis was to study, choose and decribe techniques eligible for cryptography education. A pedagogically appropriate presentation for the selected techniques' principles was to be chosen. Another goal was to create an integrated modular web interface containing a calculator focused on cryptographic operations. The eligibility of techniques was assessed accordingly to the computing processes implied by these techniques and also accordingly to the ability of being presented in an illustrative way. A program simplifying calculations used in symetric and asymetric cryptography was designed and implemented. It disposes of a web interface and one of its parts is focused on steganographic techniques. On the other hand, any pedagogically appropriate presentation interconnecting this program with theoretical findings from this field was not found.

La cryptographie à base de codes correcteurs, introduite par Robert McEliece en 1978, est un candidat potentiel au remplacement des primitives asymétriques vulnérables à l'émergence d'un ordinateur quantique. Elle possède de plus une sécurité classique éprouvée depuis plus de trente ans, et permet des fonctions de chiffrement très rapides. Son défaut majeur réside dans la taille des clefs publiques. Pour cette raison, plusieurs variantes du schéma de McEliece pour lesquelles les clefs sont plus aisées à stocker ont été proposées ces dernières années. Dans cette thèse, nous nous intéressons aux variantes utilisant soit des codes alternants avec symétrie, soit des codes de Goppa sauvages. Nous étudions leur résistance aux attaques algébriques et exhibons des faiblesses parfois fatales. Dans chaque cas, nous révélons l'existence de structures algébriques cachées qui nous permettent de décrire la clef secrète par un système non-linéaire d'équations en un nombre de variables très inférieur aux modélisations antérieures. Sa résolution par base de Gröbner nous permet de trouver la clef secrète pour de nombreuses instances hors de portée jusqu'à présent et proposés pour un usage à des fins cryptographiques. Dans le cas des codes alternants avec symétrie, nous montrons une vulnérabilité plus fondamentale du processus de réduction de taille de la clef.Pour un déploiement à l'échelle industrielle de la cryptographie à base de codes correcteurs, il est nécessaire d'en évaluer la résistance aux attaques physiques, qui visent le matériel exécutant les primitives. Nous décrivons dans cette optique un algorithme de déchiffrement McEliece plus résistant que l'état de l'art. / Code-based cryptography, introduced by Robert McEliece in 1978, is a potential candidate to replace the asymetric primitives which are threatened by quantum computers. More generral, it has been considered secure for more than thirty years, and allow very vast encryption primitives. Its major drawback lies in the size of the public keys. For this reason, several variants of the original McEliece scheme with keys easier to store were proposed in the last years.In this thesis, we are interested in variants using alternant codes with symmetries and wild Goppa codes. We study their resistance to algebraic attacks, and reveal sometimes fatal weaknesses. In each case, we show the existence of hidden algebraic structures allowing to describe the secret key with non-linear systems of multivariate equations containing fewer variables then in the previous modellings. Their resolutions with Gröbner bases allow to find the secret keys for numerous instances out of reach until now and proposed for cryptographic purposes. For the alternant codes with symmetries, we show a more fondamental vulnerability of the key size reduction process. Prior to an industrial deployment, it is necessary to evaluate the resistance to physical attacks, which target device executing a primitive. To this purpose, we describe a decryption algorithm of McEliece more resistant than the state-of-the-art.Code-based cryptography, introduced by Robert McEliece in 1978, is a potential candidate to replace the asymetric primitives which are threatened by quantum computers. More generral, it has been considered secure for more than thirty years, and allow very vast encryption primitives. Its major drawback lies in the size of the public keys. For this reason, several variants of the original McEliece scheme with keys easier to store were proposed in the last years.In this thesis, we are interested in variants using alternant codes with symmetries and wild Goppa codes. We study their resistance to algebraic attacks, and reveal sometimes fatal weaknesses. In each case, we show the existence of hidden algebraic structures allowing to describe the secret key with non-linear systems of multivariate equations containing fewer variables then in the previous modellings. Their resolutions with Gröbner bases allow to find the secret keys for numerous instances out of reach until now and proposed for cryptographic purposes. For the alternant codes with symmetries, we show a more fondamental vulnerability of the key size reduction process. Prior to an industrial deployment, it is necessary to evaluate the resistance to physical attacks, which target device executing a primitive. To this purpose, we describe a decryption algorithm of McEliece more resistant than the state-of-the-art.

<p dir="ltr">This thesis presents applications of one-point quadrature domains to encryption and decryption as well as a method for estimating average temperature. In addition, it investigates methods for finding explicit formulas for certain functions and introduces results regarding quadrature domains for harmonic functions and for double quadrature domains. We use properties of quadrature domains to encrypt and decrypt locations in two dimensions. Results by Bell, Gustafsson, and Sylvan are used to encrypt a planar location as a point in a quadrature domain. A decryption method using properties of quadrature domains is then presented to uncover the location. We further demonstrate how to use data from the decryption algorithm to find an explicit formula for the Schwarz function for a one-point area quadrature domain. Given a double quadrature domain, we show that the fixed points within the area and arc length quadrature identities must be the same, but that the orders at each point may differ between these identities. In the realm of harmonic functions, we demonstrate how to uncover a one-point quadrature identity for harmonic functions from the quadrature identity for a simply-connected one-point quadrature domain for holomorphic functions. We use this result to state theorems for the density of one-point quadrature domains for harmonic functions in the realm of smooth domains with $C^{\infty}$-smooth boundary. These density theorems then lead us to discuss applications of quadrature domains for harmonic functions to estimating average temperature. We end by illustrating examples of the encryption process and discussing the building blocks for future work.</p>

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The number of Internet of Things (IoT) devices is rising and Wireless Fidelity (Wi-Fi) networks are still widely used in IoT networks. Security protocols such as Wi-Fi Protected Access 2 (WPA2) are still in use in most Wi-Fi networks, but Wi-Fi Protected Access 3 (WPA3) is making its way as the new security standard. These security protocols are crucial in Wi-Fi networks with energy and memory-constrained devices because of adversaries that could breach confidentiality, integrity, and availability of networks through various attacks. Many research papers exist on single Wi-Fi attacks, and the strengths and weaknesses of security protocols and Wi-Fi standards. This thesis aims to provide a detailed overview of Wi-Fi attacks and corresponding mitigation techniques against IoT Wi-Fi networks in a comprehensive taxonomy. In addition tools are mentioned for each Wi-Fi attack that allows, e.g., professionals or network administrators to test the chosen Wi-Fi attacks against their IoT networks. Four types of attack (categories) were defined, Man-in-the-Middle (MitM), Key-recovery, Traffic Decryption, and Denial of Service (DoS) attacks. A set of Wi-Fi attack features were defined and decribed. The features included the security protocol and security mode, the layer (physical or data-link) that an attack targets, and the network component interaction required to allow a Wi-Fi attack to execute successfully. In total, 20 Wi-Fi attacks were selected with relevance to IoT in Wi-Fi networks based on some criteria. Additonally, each Wi-Fi attack consist of a description of possible consequences/results an adversary can achieve, such as eavesdropping, data theft, key recovery, and many more. Flow charts were also added to give the reader a visual perspective on how an attack works. As a result, tables were created for each relevant security protocol and the Open Systems Interconnection (OSI) layers to create a overview of mitigations and available tools for each attack. Furthermore, WPA3 was discussed on how it solves some shortcomings of WPA2 but has vulnerabilities of it own that lie in the design of the 4-way and dragonfly handshake itself. In conclusion, development and proper vulnerability tests on the Wi-Fi standards and security protocols have to be conducted to improve and reduce the possibility of current and upcoming vulnerabilities.

在數位內容下載市場蓬勃發展的同時，非法傳輸的流量亦不惶多讓，是以DRM機制成為了著作權利人進入網路世界的絕佳後盾，以DRM提高複製的門檻，並據以實施其商業模式，故於各數位內容核心產業皆可見DRM應用之蹤跡，卻同時引發了究竟DRM是Digital “Rights” Management 亦或Digital “Restriction” Management的爭議。是天使？或是惡魔？便形成了人們對於DRM的不同觀感。 本研究係從技術、法律以及管理三個面向分別切入，由技術面看DRM保護著作物之極限何在，由法律面看相關科技保護措施之立法造成何種影響，合理使用的空間是否因DRM之實施而造成限縮，接著由管理面向看DRM在數位內容產業價值鏈中所扮演之角色及其與價值鏈上各端權力角力衝突之關係，最後由標準面看目前DRM相關標準的運作以及互通性標準的發展趨勢。並從個案研究觀察DRM在不同產業情境中的應用。 本研究認為，DRM技術本身是中性的，其關鍵在於商業設計運用。而在盜版問題無法完全根絕之情況下，以DRM作為因應之道將使得受限內容之經濟價值不若自由流通之內容，因為內容產業的發展關鍵在於「人氣」，而盜版永遠無法取代創意與使用者對於內容之需求。因此，既然無法防堵非法傳輸之現象，則不妨與之直接面對面進行作戰，權利人既掌握了關鍵的內容，則可以針對盜版的弱點提供更優質的服務。就我國目前數位內容產業發展之情境來看，現階段或許有採取DRM進行保護的必要性，以便在推動合法消費市場之際，平衡兼顧保護著作權人以及著作利用人之權益。然而，在虛擬世界中欲全面防堵非法散佈有其技術上之侷限性，消費者亦多半養成了免費取得之使用模式與心態，因此長期而言，或許應設法從創新的商業模式來扭轉此態勢。 / Though the use of digital rights management (DRM) has been controversial, it is still widely used in the digital world. Advocates think of DRM as an indispensable way to prevent unauthorized duplication and dissemination of copyrighted works while opponents often suggest that the term “rights” should be replaced by “restriction” to best describe how DRM works. This thesis aims to analyze the issues of DRM from three perspectives. First starting with the technical point of view to see how DRM works and found out that DRM technology does have its limitation for copyright protection. That’s the reason why treaties and legislations such as the WCT, WPPT, and DMCA are needed to build the last ditch in the war with piracy. However, the attempt backfired as companies other than rights holders used it as a way to prevent market competition. As the rights holders can effectively control the access of their work with DRM, there comes another dispute about the “Paracopyright” effect. Most important of all, the use of DRM divests the users of the rights they had in the analog world, such as simply lending a book to a friend. From the perspective of management, a cost benefit analysis indicates that the benefit of using DRM to prevent unauthorized duplication obviously overwhelms by its cost and risk. In the context where the content providers, service providers, and device manufacturers all attempt to dominate the whole value chain, DRM also became one of the most powerful instruments for that purpose. Closed ecosystems are built one after another especially in the online music industry in order to bundle the consumers with specific players and music services and thus caused the antitrust issue. The online music industry and the e-book industry were chosen as case studies in the fourth chapter of the thesis. Based on different industry context, DRM strategy and its impact would differ and therefore results in a variety of business models. For example, the consumers in the US are relatively more aware of the use of DRM and are more willing to pay for authorized content. In contrast, the awareness of DRM of consumers in Taiwan is much lower and the price they are willing to pay is also far lower than what the music labels can accept. As a result, the streaming model prevails over pay-per-download model in the online music market of Taiwan. And the feasibility and necessity of DRM also varies in different industries. Before the digitalization of books, authors already had libraries providing free copies as piracy do today, and the prevalence of scanning machines and copy machines makes it even harder to prevent illegal file sharing. Accordingly, there is far less reason to use DRM in the e-book industry than in the online music industry. DRM technology is neutral in itself, and the key point is how it is designed based on different business models. The defect of DRM is neither a technical nor a legal issue, but rather a business issue. As piracy can never be eradicated, coping it with DRM would only make the value of restricted contents much less than freely distributed contents. Popularity is what really matters in the content industry. DRM has its technical limit and causes so many legal issues accompanied with the cost and risk of maintaining such fragile systems. What rights holders have in hand are the creativity and the market’s need for new content, which could never be replaced by piracy. So why not fight it face to face? Digital content industry is considered one of the most promising industries in Taiwan. However, local consumers have entrenched mindset of “free” contents. In present context, DRM is somehow needed while promoting the growth of legal market, in order to provide sufficient incentive to enrich the society with more and more creativity, and fairly protect both the rights of content providers and content users. But in the long run, a more creative or even subversive business model should be the solution to meet the trend of digital convergence.

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.

In this project you can find a study about different encryption algorithms, which are use to safeguard the information on messages over the network. We have developed a client-server application which will send information through the network which has to be secured. There are two kinds of encryption algorithms, the symmetric and the asymmetric key algorithms. Both were used to establish the communication, the asymmetric algorithm (RSA) is used to set up a symmetric key and then, all the communication process is done only with the symmetric algorithm (Blowfish). / En este proyecto encontraras un estudio sobre diferentes algoritmos de encriptación, que son usados para salvaguardar la información en mensajes por la red. Además hemos desarrollado una aplicación cliente-servidor que enviara información a través de la red de forma segura. Hay dos tipos de algoritmos de encriptación, los simétricos y los asimétricos. Ambos tipos de algoritmos son utilizados para establecer la comunicación, el asimétrico (RSA) es utilizado para establecer la clave del simétrico y a partir de entonces se utilizara exclusivamente el algoritmo simétrico (Blowfish).

The diploma thesis deals with 128–bit AES data encryption and its implementation in FPGA network card using VHDL programming language. The theoretical part explains AES encryption and decryption, its individual steps and operating modes. Further was described the VHDL programming language, development environment Vivado, FPGA network card Combo–80G and configurable framework NetCOPE. The practical part is the implementation of AES–128 in VHDL. A simulation was used to eliminate errors, then the synthesis was performed. These steps were made using Vivado software. Last step of practical part was testing of synthesized firmware on COMBO–80G card. Total of 4 projects were implemented in FPGA card. Two of them were AES encryption and decryption with ECB mode and another two describe the encryption and decryption with CBC mode.