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Analýza návrhu nových hašovacích funkcí pro soutěž SHA-3
Marková, Lucie ; Tůma, Jiří (advisor) ; Hojsík, Michal (referee)
In the present work we study a linearization framework for assessing the security of hash functions and analyze the proposal of hash function BLAKE. The thesis demonstrates a limitation of a method presented in the linearization framework for which the method could not be applied to the full extent. Further in the thesis, it is explained how to find a message difference for second preimage attack with the help of linear codes. To that end, a matrix representing the linearized compression function of BLAKE is constructed. My thesis as a PDF file and source codes of computations that I created in Mathematica software are on an enclosed CD.
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Evolutionary Design of Hash Functions
Kidoň, Marek ; Bidlo, Michal (referee) ; Dobai, Roland (advisor)
Hash tables are fast associative array implementations which became part of modern world of information technology and thanks to its simplicity became very popular among computer programmers. The choice of proper hash function is very important. Improperly selected hash function can result in poor hash table performance and its application. Currently there are many exceptional implementations of general hash functions. Such functions are not constrained to a concrete set of inputs, they perform on any input. On the other hand if we know the input domain we can design a specific hash function for desired application thus reaching better levels of performance compare to a general hash function. However hash function design is not trivial. There are no rules, standards, guides nor automated tools that would help us with such a task. In case of manual design the hash function author has to rely on his/her knowledge, experience, inventiveness and intuition. In case of such complicated tasks there is sometimes advantageous to choose a different path and use techniques such as evolution algorithms. Natural computing is an approach of certain problem solutions that are inspired by the process of species reproduction as defined by Charles Darwin. In this thesis we will design hash functions for the domain of IP addresses, that serve as an unique network device interface identifier in internet protocol networks. The chosen subset of natural computing is the genetic programming, a very specific technique that is an adequate approach to our problem thanks to its properties. Evolutionary designed hash functions offer good properties. They outperform state-of-the-art generic, human-created hash functions in terms of speed and collision resistance.
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Trusted long-term digital archive
Mravec, Roman ; Dzurenda, Petr (referee) ; Člupek, Vlastimil (advisor)
The bachelor's thesis is focused on problematics of long-term trusted preservation. Security and trustworthiness of electronic documents is one of the main aim of this research. Provides means needed to keep and maintain data integrity, non-repudiation, long-term readibility and legally-binding of electronic documents. Solves time resistant formats for archive data files. Contains design of trusted long-term archive based on valid laws and standards in field of electronic preservation.
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Secure communication in systems using restricted devices
Michálek, Tomáš ; Martinásek, Zdeněk (referee) ; Malina, Lukáš (advisor)
This thesis presents the usability and analysis of cryptographic methods on devices with low computing power and low memory capacity. The thesis describes different methods and shows examples of their usability in practice. According to certain parameters of security methods, such as code size and memory size it is selected and compared symetric ciphers and authentication codes. There are also described some security protocols and possible attacks. The next part includes a comparison of ciphers and chosen candidates are tested on our microcontroller. In the end there are propose, implemented and analyzed security protocols.
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Neural networks in cryptography
Borkovec, Tomáš ; Rášo, Ondřej (referee) ; Martinásek, Zdeněk (advisor)
Bachelor's thesis aims to introduce neural networks and their properties, which can be used for creating cryptographic protocols based on neural networks. It proposed concrete use of neural networks in cryptography and creates a teoretical basis for the practical implementation. In practical section is discusses the creation of neural network on which we based cryptographic model. The constructed models are then subjected to testing. At the close of the thesis we discussed the advantages and disadvantages of possible use in real cryptographic modules.
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Electronic Registry for Local Authority
Stránský, Karel ; Burget, Radek (referee) ; Rychlý, Marek (advisor)
Bachelor thesis "Electronic registry for local authority" is focused on usage of electronic registries for electronic communication between citizens and public authority. The first part describes the legislative page incidental with e-registries, principles of their functionality, and important requierements which are set on e-registiries. Furthermore elementary electronic signature's informations are included, along with creation and verification, and informations about certificates and certification authorities. The usage of digital signature at communication with electronic registry is also described. The second part is used to present particular concept of implemented sample electronic registry's system, and the solution of picked problems.
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Application for Demonstration of Hash Algorithms SHA-1 and SHA-2
Siska, Josef ; Petrlík, Jiří (referee) ; Novotňák, Jiří (advisor)
In this thesis, the theory related to the hash algorithms SHA-1 and SHA-2 is presented, along with a description of possible implementation of an application that demonstrates how these algorithms work. The first part of this thesis describes the principles of construction of hash functions, their use and history of selected hash functions. The two following chapters present conventions and algorithms of the SHA-1 and SHA-2. The next chapter describes the general concepts related to the attacks on the hash functions and selected attacks are presented in more detail. The last two chapters outline the design and implementation of an application that was created as part of this work. In the end the evaluation of results of this thesis and proposals for its possible continuation are presented.
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Modular Content Management System in ASP.NET
Michalovič, Miroslav ; Karásek, Jan (referee) ; Malina, Lukáš (advisor)
This bachelor thesis contains a proposal of a content management system, created according to the standards usually required of systems working with content management, these standards are the object of the opening chapter. In this chapter, options of the realization and their advantages are also discussed. The system is realized through ASP.NET, which is a part of a bigger .NET Framework, a platform, which also comprises of some additional technologies, which were used in the project. The technologies used during the application development are discussed in the second chapter. The content management in the proposed application would not be possible without a functional database, which the third chapter describes. A relational database model based on a client-server communication using SQL inquiries was selected for the developed application. The fourth chapter is dedicated to the application creation itself, which is made of a simple interface for the synchronization of clients’ replies to the events of logged users. This chapter also contains a database proposal and a description of the individual application content. The final chapter is dedicated to the security of the project along with the potential risks description and their existing or proposed solutions. The appendices shows the visual part of application and it’s components.
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System for Loging Changes in Operating System
Pečeňa, Jan ; Smrčka, Aleš (referee) ; Peringer, Petr (advisor)
Bachelor's thesis describes the design and implementation of applications for the detection of changes in the operating system. Window´s registry, registry key, subkey and value are explained in introductory part. Hash function needed to identify the changed files is explained too. The created application is fully functional and works with 32 and 64 bit versions of Windows. Actual state is saved in the first run. Changes in operating system are detected in the second run. Operating system is installed in a VMWare virtual machine.
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Network Anomaly Detection
Bartoš, Václav ; Kořenek, Jan (referee) ; Žádník, Martin (advisor)
This work studies systems and methods for anomaly detection in computer networks. At first, basic categories of network security systems and number of methods used for anomaly detection are briefly described. The core of the work is an optimization of the method based on detection of changes in distributions of packet features originally proposed by Lakhina et al. This method is described in detail and two optimizations of it are proposed -- first is focused to speed and memory efficiency, second improves its detection capabilities. Next, a software created to test these optimizations is briefly described and results of experiments on real data with artificially generated and also real anomalies are presented.
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