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Library of Algorithms for Text Ciphering
Vozák, Petr ; Řezníček, Ivo (referee) ; Kubíček, Radek (advisor)
p, li { white-space: pre-wrap; } p, li { white-space: pre-wrap; } This thesis deals with text ciphering. The presented paper describes at first basic theoretical background of cryptology and basic distribution of cryptographic algorithms. Then it describes a brief history of encryption from beginning to present. Theoretical description of ciphering methods and its implementation details are discussed here. All basic types of conventional encryption algorithms and also some modern ciphering methods are included; these are substitution, transposition, steganographic or combinations encryption systems. The result of this thesis is the library of algorithms for text ciphering in Java with a sample application, which demonstrates its funcionality.
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Implementation of Encryption Algorithms in VHDL Language
Kožený, Petr ; Martínek, Tomáš (referee) ; Kořenek, Jan (advisor)
This thesis deals with design and implementation of AES and DES encryption architectures for embedded systems. Architectures are implemented in VHDL language and design for FPGA technology. The proposed implementations are mapped on the Xilinx Spartan 3 technology. Both architectures are applied in simple ECB (Electronic Codebook) scheme with cache memories. A maximum throughput of design DES architecture 370 Mbps is achived with clock frequency of 104 MHz. The throughput of AES architecture at the maximum clock frequency of 118 MHz is 228 Mbps. Compared to software implementations for embedded systems, we achieve significantly higher throughput for both architectures.
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Message Encryption over Text Messengers for Android
Balvín, David ; Burget, Radek (referee) ; Kolář, Dušan (advisor)
The main purpose of this thesis is to design and implement an application that would handle encrypted communication using several protocols or existing applications. The application is able to handle automatic encryption using a symetric-key algorithm for sending messages and decryption on demand for receiving/reading messages. It also supports asymetric exchange of keys for symetric encryption. A simple user interface is also created for this application, taking ideas from default SMS application for Android and popular Messenger a Whatsapp.
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System of anonymous data collection
Troják, David ; Malina, Lukáš (referee) ; Dzurenda, Petr (advisor)
This thesis deals with contemporary approaches that provide higher protection of privacy of users. It focuses mainly on a group signature. In the practical part of this thesis I designed and implemented PS that is enable to gather information with the help of signal of a mobile device. The application was designed in accordance with fundamental cryptographic requirements such as the authenticity and the integrity of transmitted data. The anonymity of users is guaranteed through an application layer (the group signature) as well as through a network layer (Tor).
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Using Near-Field Communication (NFC) to Improve Messaging Privacy on Android OS
Karmazín, Jaromír ; Trchalík, Roman (referee) ; Očenášek, Pavel (advisor)
V této práci vytváříme jednoduchý systém pro rychlou textovou komunikaci (IM), který využívá technologii Near-Field Communication (NFC) ke zlepšení bezpečnosti a soukromí. V první části zkoumáme samotnou technologii NFC. Poté se věnujeme možnostem NFC v operačním systému Android pro chytrá mobilní zařízení a také existujícím aplikacím, které tyto možnosti využívají. Rovněž zkoumáme nejmodernější přístup k bezpečnému IM, zejména Signal Protocol a jeho open-source implementaci pro Android. Dále pak navrhujeme IM systém, který používá Signal Protocol pro šifrování zpráv a NFC pro výměnu kryptografického materiálu, aniž by vyžadoval použití telefonních čísel nebo důvěryhodnou třetí stranu. Nakonec předkládáme vzorovou implementaci klientské i serverové aplikace a zhodnocení vlastností tohoto systému z hlediska soukromí a bezpečí.
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Infrastructure of public keys
Bědajánek, Ondřej ; Malý, Jan (referee) ; Pust, Radim (advisor)
The subject of my thesis dscribes function and principles of the public key infrastructure as well as certificate authority. Under the operation system Linux was created self signed certificate authority. Web interface was devoloped in PHP for the purpose of the generation, distribution and rejection certificates. Configuration files for OpenVPN are included in the thesis and wireless security is achived by OpenVPN.
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Library of Algorithms for Text Ciphering
Mikulka, Jiří ; Havel, Jiří (referee) ; Kubíček, Radek (advisor)
This thesis brings an overview of historical and modern methods and approaches used in cryptography. It also describes and assesses ciphers, which have been used since the very beginning of encryption till modern ciphers. Based on information resulting from this overview the reader should be able to distinguish between ciphers, know their advantages and disadvantages, and be able to choose the best cipher for any purpose. Ciphers mentioned in this thesis are implemented in a library called CipherLib , which shows usage of every described cipher.
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Web applications for user authentication
Vybíral, Petr ; Dzurenda, Petr (referee) ; Hajný, Jan (advisor)
The thesis deals with the problems of user authentication. The first chapter analyzes the problem of authentication, its methods and its utilization. The second chapter presents the different security options for communication. The chapter describes security, communication and authentication protocols. There is the 2D barcode QR Code described at the end of the chapter. The third chapter is devoted to ASP.NET technology, its development and possibilities of utilization. Attention is focused on web form and server controls. There is an analysis of elements of cookies and possibilities of their use. The last chapter consists of a practical part, which describes the development of a web application. There is a description of the parts of application, such as the database, the Web navigation, master pages and etc. in the following chapter. The cardinal part of the chapter consists of an analysis and implementation of forms authentication, the attribute authentication and authentication with QR code. Finally, there is a description of way how to secure the communication by using a certificate.
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Digital Image Steganography
Mazánek, Antonín ; Šimek, Václav (referee) ; Strnadel, Josef (advisor)
This bachelor's thesis introduces the steganography scientific discipline. It presents its ancient and relative recent history, mentions its current use and outlines the possible directions for steganography future. It introduces steganography into context of hiding information superior domain and highlights differences between other methods in this domain. It describes steganography subdivisions and closer deals with digital image steganography. It presents some known methods and types of digital image data. The thesis also contains more detailed description of image data in PNG format. It describes the implementation of LSB and PVD steganography methods with images in PNG format as cover object and evaluates their key properties, namely: imperceptibility, capacity and robustness. At the end of the thesis, the author's reflection on the results and possibilities of further modifications of the mentioned methods is given.
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