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Authentication Protocols and Privacy Protection
Hajný, Jan ; Vozňák, Miroslav (referee) ; Vaněk,, Tomáš (referee) ; Burda, Karel (advisor)
Tato dizertační práce se zabývá kryptografickými prostředky pro autentizaci. Hlavním tématem však nejsou klasické autentizační protokoly, které nabízejí pouze ověření identity, ale tzv. atributové autentizační systémy, pomocí kterých mohou uživatelé prokazovat svoje osobní atributy. Tyto atributy pak mohou představovat jakékoliv osobní informace, např. věk, národnost či místo narození. Atributy mohou být prokazovány anonymně a s podporou mnoha funkcí na ochranu digitální identity. Mezi takové funkce patří např. nespojitelnost autentizačních relací, nesledovatelnost, možnost výběru prokazovaných atributů či efektivní revokace. Atributové autentizační systémy jsou již nyní považovány za nástupce současných systémů v oficiálních strategických plánech USA (NSTIC) či EU (ENISA). Část požadovaných funkcí je již podporována existujícími kryptografickými koncepty jako jsou U-Prove či idemix. V současné době však není známý systém, který by poskytoval všechny potřebné funkce na ochranu digitální identity a zároveň byl prakticky implementovatelný na zařízeních, jako jsou čipové karty. Mezi klíčové slabiny současných systémů patří především chybějící nespojitelnost relací a absence revokace. Není tak možné efektivně zneplatnit zaniklé uživatele, ztracené či ukradené autentizační karty či karty škodlivých uživatelů. Z těchto důvodů je v této práci navrženo kryptografické schéma, které řeší slabiny nalezené při analýze existujících řešení. Výsledné schéma, jehož návrh je založen na ověřených primitivech, jako jsou $\Sigma$-protokoly pro důkazy znalostí, kryptografické závazky či ověřitelné šifrování, pak podporuje všechny požadované vlastnosti pro ochranu soukromí a digitální identity. Zároveň je však návrh snadno implementovatelný v prostředí smart-karet. Tato práce obsahuje plný kryptografický návrh systému, formální ověření klíčových vlastností, matematický model schématu v programu Mathematica pro ověření funkčnosti a výsledky experimentální implementace v prostředí .NET smart-karet. I přesto, že navrhovaný systém obsahuje podporu všech funkcí na ochranu soukromí, včetně těch, které chybí u existujících systémů, jeho výpočetní složitost zůstává stejná či nižší, doba ověření uživatele je tedy kratší než u existujících systémů. Výsledkem je schéma, které může velmi znatelně zvýšit ochranu soukromí uživatelů při jejich ověřování, především při využití v elektronických dokladech, přístupových systémech či Internetových službách.
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A Web Presentation of JShelter Project
Krčma, Jan ; Polčák, Libor (referee) ; Bednář, Martin (advisor)
This thesis deals with creating user-friendly web presentation of the project JShelter, in which its advantages in terms of the safety of its users when navigating the World Wide Web are highlighted, so that their anonymity and at the same time the functionality of the visited sites are sufficiently preserved. Above all, the result provided by the JShelter browser extension against tracking the user based on the deviation of his internal clock and also the confirmation of the same-origin policy protection will be shown.
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Anonymous communication in Internet environment
Pajtinová, Mária ; Malina, Lukáš (referee) ; Hajný, Jan (advisor)
Master´s thesis focuses on certain possibilities of how user can anonymously commununicate through the Internet. There are described following anonymous programs: TOR, JAP, I2P and CyberGhost, which allow user to hide his own identity to other IP address. Subsequently, measurements from different technologies are made by anonymous program TOR for calculate transmission speed.
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Authentication using a mobile phone
Križan, Viliam ; Hajný, Jan (referee) ; Malina, Lukáš (advisor)
Bachelor’s thesis describes the basics of authentication methods by knowledge, used authentication tokens and biometric ways of authentication. It discusses the capabilities of the individual methods designed for mobile phones. It covers the basic security in the GSM network (using SIM cards) and usage of authentication based on passwords, PIN codes, gestures, facial recognition and speech recognition. Thesis evaluates individual methods in terms of success and performance. It discusses the usage possibilities of authentication methods on the Android platform, where it provides the options of modular arithmetic operations of cryptographic primitives. The work evaluates the time consumption of modular arithmetic operations on the mobile phones with created application. It also lists available algorithms of symmetric and asymmetric ciphers, one-way hashes on the Android platform. The section of authentication protocol conception writes about protocol based on zero-knowledge proof, which authenticates users anonymously. It also proposes the transfer of calculated authentication variables using NFC technology. The protocol also supports the revocation of malicious users. The goal of the thesis was to create two applications that have implemented the selected authentication protocol. The first application designed for users, runs on mobile phones with Android operating system. Application calculates the authentication variables using authentication parameter which it loads from secure element of the phone. After calculations it sends the authentication variables via NFC reader (connection phone – reader). NFC reader is connected to the second application, which verifies the user’s authentication variables and decides the conclusion of authentication. The last part of thesis is devoted to testing the developed applications and running them on the devices. It evaluates the security of the authentication protocol, usage of the phone’s secure element and a security of the transmission over NFC.
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Secure and privacy-preserving data communication
Bernát, Michal ; Člupek, Vlastimil (referee) ; Malina, Lukáš (advisor)
This thesis discusses the possibility of ensuring the safety, integrity and authenticity of data communication with respect to user privacy. This thesis describes the fundamentals of smart grid networks with capabilities of existing forms of security to communications that have been chosen as a target for application deployment of group signatures to ensure the security, integrity and authenticity of data communications. It describes the concept of a zero-knowledge and cryptography primitives. Further, the basic principles are presented, the history of development, and various schemes are compared based on the construction and performance. The second part is given to the deployment and optimization of group signatures for computationally limited devices. Within the draft report were to be implemented in the Java language chosen scheme HLCCN, DP and BBS. They were then tested under various platforms which were measured and evaluated performance parameters of the schemes. The optimization of the work is focused on the times of signatures, which are critical to a smart grid system. Under the platforms are deployed pre-processed pairing optimization methods and other methods resulting from the deployment platform as JPBWrappera and native libraries to deliver more efficient times of sgnaiture. At the end of the thesis are evaluated achievements of optimization methods and the appropriateness of the deployment of smart grids.
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Anonymous communication on the internet
Hořejš, Jan ; Babnič, Patrik (referee) ; Rosenberg, Martin (advisor)
The objective of this master’s thesis was to describe current capabilities of anonymous browsing over the Internet. The theoretical part focuses on three main methods of anonymization with main focus on Tor network. The master‘s thesis describes advantages and disadvantages of different solutions and possible attacks on them. In the next part is demonstrated Tor network, implementation of Hidden service and secured access to the server for clients and possible attacks against this proposal. The work also includes the results of measurements of all three anonymizers and the effects on their speed.
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Anonymity in P2P Networks
Brunai, Adam ; Malinka, Kamil (referee) ; Barabas, Maroš (advisor)
Freedom of speech and the right to privacy are maybe the most important elements of a modern society, yet the rights are often violated. This fact was the main reason for writing this thesis covering P2P network models, anonymity, censorship resistance and their use in real P2P networks and publishing systems. We discuss their effectiveness and suitability for specific purposes, but also the security considerations of their use. The second part of this thesis presents the LSPP publishing protocol, which is an library implementation of an anonymous censorship resistant P2P network. Finally, we analyze the proposed protocol and compare it with existing solutions.
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Dark Web and Cryptocurrency
BOLATOV, Nugerbek
This study aims to explore the principle of the interdependence and mutual influence of the Dark web and cryptocurrency. Specifically, it explores the terms "the Dark web" and "cryptocurrency", as well as distinguishes cryptocurrency from normal currency. Furthermore, it establishes a connection between the Dark web and cryptocurrency. In order to reach the aim of this study, multiple sources of literature had been analyzed, including books and online articles. The analysis of literature shows that there is a strong correlation between the existence of the Dark web and demand on cryptocurrency. Thus, the results of this paper conclude that the Dark web and cryptocurrency exist in symbiosis - cryptocurrency allows the Dark web to exist for its anonymity and impunity, while the Dark web guarantees demand on cryptocurrency.
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A job description of a social worker at low-threshold facility for children and youth
KOLÁŘOVÁ, Sandra
This bachelor's thesis describes the content of work of a social worker in a specific facility NZDM Ostrov Naděje. The work is divided into two chapters. The first chapter deals with a theoretical view of NZDM from a general level. The second chapter compares the theoretical information from the first chapter with the practice in a particular NZDM in the form of an essay. In the end, there is a reflection on whether it is possible for general standards to be applied in practice without much difficulty.
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Reinventing the blurry oval: Practitioner perceptions of deepfakes as a tool for anonymisation in documentary film and video journalism
Weatherald, Nathalie Alice ; Lábová, Sandra (advisor) ; Silverio, Robert (referee)
In 2020, the documentary film Welcome to Chechnya disguised the sources it portrayed using deepfake-like 'digital masks', to wide acclaim: many described the use of the technology in this way to be game-changing for the industry. This qualitative study examines documentary filmmakers' and video journalists' (practitioners') perceptions of the benefits and limitations of the use of deepfakes, or AI-assisted synthetic media, to anonymise sources in their work, in the context of theoretical understandings of photographic realism and applied journalistic ethics. Through one unstructured interview with the film's visual effects supervisor, Ryan Laney, and eight semi-structured interviews with practitioners who have previously visually disguised sources, the study identifies four key themes of practitioners' views about the use of deepfakes as a tool to anonymise: the impacts on practitioner-source relations, practical considerations, aesthetic impacts of synthetic media and broader industry implications. Overall, practitioners emphasised the limitations of the potential use of deepfakes in this context, much more than the benefits.
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