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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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Modern access control system
Vomáčka, Martin ; Hajný, Jan (referee) ; Malina, Lukáš (advisor)
The thesis describes the design of scheme for access system with user authentication via smart cards. The first chapter explains various types of identification items used for authentication of users and different types of readers and terminals, followed by chapter 2 with a deeper insight on smart cards with focus on their types, what internal structure and principle of communication with card readers are used, etc. with primary focus on Java cards. The third chapter describes Java Card cryptography - especially elliptic curve cryptography used on this platform. The fourth part focuses on PACE protocol with subsections dedicated to the individual parts of the protocol and its applicability to smart cards environment. Chapter 5 explains the proposed design of the authentication scheme elaborated in the thesis, including a detailed description of specific parts, their funcionality and exemplary usage in the created applications.
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Safe Cryptography Algorithms
Zbránek, Lukáš ; Schäfer, Jiří (referee) ; Chmelař, Petr (advisor)
In this thesis there is description of cryptographic algorithms. Their properties are being compared, weak and strong points and right usage of particular algorithms. The main topics are safeness of algorithms, their bugs and improvements and difficulty of breaching. As a complement to ciphers there are also hash functions taken in consideration. There are also showed the most common methods of cryptanalysis. As a practical application of described algorithms I analyze systems for secure data transfer SSH and SSL/TLS and demonstrate an attack on SSL connection. In conclusion there is recommendation of safe algorithms for further usage and safe parameters of SSH and SSL/TLS connections.
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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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Authentication protocols on restricted devices
Šebesta, David ; Člupek, Vlastimil (referee) ; Malina, Lukáš (advisor)
This thesis deals with authentication methods, especially about authentication based on knowledge. In the thesis, the hash functions such as MD hash function, SHA hash function, Keccak, Blake, Grostl, Jh, Skein are described and shown their compilation on low frequency microcontrollers. Into the microcontroller MSP430F2274 are Keccak, Blake, Grostl, JH, md5, SHA–1, SHA–224, SHA–256 a Skein hashing algorithms implemented and measured. Also simple authentication protocols client–server are designed and their implementation and measuring was done. Protocols are focused on low memory requirement and the smallest number of measured messages during authentication. The first solution is determined for the beginning of the communication from client and the second from server.
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Secure Transport of NetFlow Data
Ručka, Tomáš ; Halfar, Patrik (referee) ; Grégr, Matěj (advisor)
The aim of my bachalor's thesis is secure transport NetFlow data. Communication in NetFlow is not protected against unauthorized intrusion, in addition works over UDP protocol which is protocol that allows data loss. The aim of this work is to create an encrypted tunnel through which communication will take place between the exporter and collector.
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P4 cryptographic primitive support
Cíbik, Peter ; Malina, Lukáš (referee) ; Smékal, David (advisor)
This diploma thesis deals with the problem of high-speed communication security which leads to the usage of hardware accelerators, in this case high-speed FPGA NICs. Work with simplification of development of FPGA hardware accelerator applications using the P4 to VHDL compiler. Describes extension of compiler of cryptographic external objects support. Teoretical introduction of the thesis explains basics of P4 language and used technologies. Describes mapping of external objects to P4 pipeline and therefore to FPGA chip. Subsequently deals with cryptographic external object, compatible wrapper implementation and verification of design. Last part describes implementation and compiler extension, cryptographic external object support and summarizes reached goals.
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Identification and characterization of malicious behavior in behavioral graphs
Varga, Adam ; Burget, Radim (referee) ; Hajný, Jan (advisor)
Za posledné roky je zaznamenaný nárast prác zahrňujúcich komplexnú detekciu malvéru. Pre potreby zachytenia správania je často vhodné pouziť formát grafov. To je prípad antivírusového programu Avast, ktorého behaviorálny štít deteguje škodlivé správanie a ukladá ich vo forme grafov. Keďže sa jedná o proprietárne riešenie a Avast antivirus pracuje s vlastnou sadou charakterizovaného správania bolo nutné navrhnúť vlastnú metódu detekcie, ktorá bude postavená nad týmito grafmi správania. Táto práca analyzuje grafy správania škodlivého softvéru zachytené behavioralnym štítom antivírusového programu Avast pre proces hlbšej detekcie škodlivého softvéru. Detekcia škodlivého správania sa začína analýzou a abstrakciou vzorcov z grafu správania. Izolované vzory môžu efektívnejšie identifikovať dynamicky sa meniaci malware. Grafy správania sú uložené v databáze grafov Neo4j a každý deň sú zachytené tisíce z nich. Cieľom tejto práce bolo navrhnúť algoritmus na identifikáciu správania škodlivého softvéru s dôrazom na rýchlosť skenovania a jasnosť identifikovaných vzorcov správania. Identifikácia škodlivého správania spočíva v nájdení najdôležitejších vlastností natrénovaných klasifikátorov a následnej extrakcie podgrafu pozostávajúceho iba z týchto dôležitých vlastností uzlov a vzťahov medzi nimi. Následne je navrhnuté pravidlo pre hodnotenie extrahovaného podgrafu. Diplomová práca prebehla v spolupráci so spoločnosťou Avast Software s.r.o.
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Software support for cryptography system training based on discrete logarithm
Kříž, Jiří ; Zeman, Václav (referee) ; Burda, Karel (advisor)
Current needs of human communication came to status, when most of transferred messages are considered as private and transition over non-secured communication lines in open form is not possible. That originated a lot of different methods for securing of messages and transfers in ciphered form. Two mainstreams were established, symmetric cryptography and asymmetric cryptography. Second of mentioned groups is based on usage of two information – keys, when one of then is broadly known and is public and second, well protected and private. Using a public key it is possible to establish a cryptogram of message, but for deciphering it is necessary to know private key. Asymmetric methods are based on mathematical problems, for which there is not an effective computing algorithm. This thesis are focused for asymmetric cryptosystems based on discrete logarithm problem, where ciphering of message using public key is very easy and quick, but deciphering without knowledge of private key is extremely time consuming process. Work describes a mathematical base of discrete logarithm problem, its’ properties and methods developed for solving of this problem. Descriptions of particular cryptosystems are given, i.e. ElGamal cryptosystem, Diffie-Hellman protocol and DSA. Second part of thesis is focused for web application developed as study support of discrete logarithm problem and of cryptosystems using this problem. It describes functional and graphical interface, work with it and options given to user working with application. Mentions also lessons for user which should help with understanding of described problems and practicing.
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