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Hash functions and their usage in user authentication
Piller, Igor ; Stančík, Peter (referee) ; Hajný, Jan (advisor)
This thesis concerns with hash functions and their usage in authentication. It presents basics of hash functions theory and construction elements. In particular the thesis focuses on LMHash, MD4, MD5 and SHA family hash functions, which are compared from the security point of view. The thesis describes in general the most frequently used hash function attacks, points out the weaknesses of current construction and mentions the future perspective of hash functions. Furthermore the thesis outlines the area authentication and describes usage of hash functions in the area. Practical part of the thesis contains an implements of a general authentication framework implemented in programming language C#. The result is client and server applications, in which two selected authentication methods were successfully tested. The result implementation is flexible with respect to the possible future use of other authentication methods.
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Cryptography on Computationally Limited Devices
Hampl, Dalibor ; Hajný, Jan (referee) ; Malina, Lukáš (advisor)
The thesis focuses on cryptographic algorithms of low performance devices, and mutual authentication of authentication server and user using smart cards. In the first part of this thesis the cryptography, cryptographic primitives, cryptographic goals, security models and cryptographic algorithms of low performance devices are presented. The second part focuses on low performance devices as RFID tags, NFC technology, microcontrollers and smart cards (.NET cards, java cards, MIFARE cards). The practical part deals with the comparison of chosen low performance devices and measure the time required for encryption and decryption using different cryptographic algorithms on Gemalto .NET Smart Card V2+. This thesis describes and explains the three authentication schemes for mutual authentication of remote server and user using smart cards. The new authentication scheme, which is based on the second related scheme, attempts to eliminate possible security attacks and keeps efficiency. For all four authentication schemes the application is implemented to test required time for authentication of server and user using smart cards.
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Duplicate Text Identification
Pekař, Tomáš ; Kouřil, Jan (referee) ; Smrž, Pavel (advisor)
The aim of this work is to design and implement a system for duplicate text identification. The application should be able to index documents and also searching documents at index. In our work we deal with preprocessing documents, their fragmentation and indexing. Furthermore we analyze methods for duplicate text identification, that are also linked with strategies for selecting substrings. The thesis includes a description of the basic data structures that can be used to index n-grams.
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Portal for the support of cryptography instruction
Forman, Tomáš ; Doležel, Radek (referee) ; Zeman, Václav (advisor)
The main goal of this master's thesis is building of web portal for presentation basic cryptography algorithms. Those algorithms would be explained in the theoretical page in the first place. After that, they would be demonstrated by scripts. One part of this project is designing simplified theoretical element for basic impletion portal of information. Next part is creating web portal by one of the free available CMS´s systems. Programming language JAVA would be used as an instrument for creating demonstration scripts. For creating animations will be used the Flash animation tool. Target of formed web portal is creating community of expert public. It would make new articles, scripts and knowledge. This way, the portal would be kept current. The section which would include failure the most widely used algorithms and instructions how to eliminate it will be part of portal.
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Software library of basic symmetric and asymmetric primitives of modern cryptography on embedded platforms
Miška, Matěj ; Mlýnek, Petr (referee) ; Lieskovan, Tomáš (advisor)
This master thesis deals with a search of cryptographic primitives for embedded systems, which are tested on Raspberry Pi platforms and the results compared in the subsequent practical part. The content of the research is an explanation of the use of cryptography in information systems, an example of a protocol using cryptography in the energy sector, the selection of cryptographic primitives based on recommendations from security institutions, a description of Raspberry Pi embedded platforms and an introduction of cryptographic libraries providing tools to perform cryptographic operations. The theoretical part of the thesis results in an overview of the information needed to create a test tool. The subsequent practical part deals with the theoretical design of the required tool, the determination of the functions that the tool must have and the way of performing the testing. This is followed by a description of the choice of the programming language and development environment suitable for this work, together with a description of the internal structure of the developed application. The testing parameters are mainly the computational, memory and time requirements of the cryptographic primitives on the system. The paper concludes with methods of running and controlling the application, possible presentation of the measured results, the actual results of testing the selected embedded platforms and a discussion of these results.
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User verification based on smart-phones
Bělík, David ; Malina, Lukáš (referee) ; Hajný, Jan (advisor)
The main aim of this diploma thesis is to get acquainted with the area of secure authentication and authorization of users in smartphones on the Android platform. Individual types of encoding, authentications, authentication devices and characteristics of QR codes are decribed in the chapters. In the practical part of this thesis the applications are created with an implemented authentication scheme, which is being developed at FEKT VUT in Brno. The client part of the application, that generates QR code, as well as the server part, that verifies the authenticity of the data, are set up.
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Password deposition techniques in operating systems
Pavlík, Martin ; Růčka, Lukáš (referee) ; Hajný, Jan (advisor)
This master thesis deals with ways to store passwords in current operating systems. Specifically, this work focuses on Windows, Linux, BSD and OS X. These systems are examined for ways of hashing passwords and on resistance of resulting hashes against various attacks. First (theoretical) section describes the procedures and algorithms that are needed for user authentication. This part also describes methods of hash storing. At the end of the theoretical part are generally described some possible attacks against hash functions. In second (practical) part is described and tested tools for obtaining hashes of the investigated operating systems. Subsequently practical attacks were conducted against obtained hashes by using appropriate tools. Furthermore there are presented results of the attacks. In the conclusion of the work there is a comparison of tools and methods which were used to obtain plaintext passwords from operating systems.
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Group signature schemes
Smrž, Jan ; Dzurenda, Petr (referee) ; Malina, Lukáš (advisor)
Digital signatures are widespread in IT nowadays. In some cases there is emphasized the security of signer identity when signing an electronic message. For this type of signature group digital signatures are suitable. In this thesis basic cryptographic functions are presented which are used for group digital signatures. The principle of group signatures is explained, its advantages and nowadays use. Further are explained electronic election and it dis- and advantages. The practical part is a design and implementation of system suitable for electronic election allowing anonymity of voters using group digital signatures.
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Cryptocurrency
Šelinga, Martin ; Komosný, Dan (referee) ; Zeman, Václav (advisor)
In this bachelor thesis are analyzed elementary cryptographical techniques which are used among others also in cryptocurrencies. In second part is analysis and detail description of most used cryptocurrencies. In last part is description of simple web application which will demonstrate function of cryptocurrencies.
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