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Modern Asymmetric Cryptosystems
Walek, Vladislav ; Sobotka, Jiří (referee) ; Malina, Lukáš (advisor)
Asymmetric cryptography uses two keys for encryption public key and for decryption private key. The asymmetric cryptosystems include RSA, ElGamal, Elliptic Curves and others. Generally, asymmetric cryptography is mainly used for secure short messages and transmission encryption key for symmetric cryptography. The thesis deals with these systems and implements selected systems (RSA, ElGamal, McEliece, elliptic curves and NTRU) into the application. The application can test the features of chosen cryptosystems. These systems and their performance are compared and evaluated with the measured values. These results can predict the future usage of these systems in modern informatics systems.
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Efficient Digital Signature Schemes
Varga, Ondrej ; Sobotka, Jiří (referee) ; Malina, Lukáš (advisor)
Digital signatures, which take the properties of classical signatures, are used to secure the actual content of documents, which can be modified during transmission over an insecure channel. The problems of security and protection of communicating participants are solved by cryptographic techniques. Identity verification, message integrity, credibility, the ownership of documents, and the secure transmission of information over an unsecured channel, are all dealt with in secure communications - Public Key Infrastructure, which uses digital signatures. Nowadays digital signatures are often used to secure data in communication over an unsecured channel. The aim of the following master’s thesis is to familiarize readers with the necessary technological aspects of digital signatures, as well as their advantages and disadvantages. By the time digital signatures are being used they will have to be improved and modified to be secure against more sophisticated attacks. In this paper, proposals of new efficient digital signature schemes and their comparison with current ones are described. Also are examined their implications for computationally weak devices, or deployment in low speed channel transmission systems. After an explanation of cryptography and a description of its basic subjects, digital signatures are introduced. The first chapter describes the possible formatting and architecture of the digital signature. The second part of this master’s thesis is about current digital signature schemes and their properties. Chapter 3 describes some proposals of new efficient digital signature schemes and their comparison to those currently in use. In the practical part, the implementations (in the environment .NET in C#) of two effective digital signature schemes as part of a client-server application are presented and described (Chapter 4). In the last chapter the comparison and analysis of the implemented signature schemes are provided.
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Engineering solution of photovoltaic power station
Gajdošík, Ivo ; Sobotka, Jiří (referee) ; Míča, Ivan (advisor)
This thesis deals with the usage of solar photovoltaic panel production of electic energy. First part focuses on solar radiation alighting the Earth, respectively the area of Czech republic. Next part covers a development of photovoltaic from the very beggining til nowadays, it describes its spread in the world and the area of Czech republic. Then a reader us introduced to physical principles that work inside solar cells a one single chapter desribes individual parts of photovoltaic power station. Next chapter is dedicated to a model study of photovoltaic power station devided in two alternates- with stacionary placement of panel and placement on trackers, where after a market research, there is a whole technical solution designed and economical and delivery balance is calculated. At the last part there are described main directions of development in the field of usage of solar energy for electric current production.
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Smart Card side channels
Pospíšil, Karel ; Martinásek, Zdeněk (referee) ; Sobotka, Jiří (advisor)
The thesis is dealing with smart cards and describes the known types of side channel attacks. Smart card belongs into the group of the youngest and smartest cards. In the card body, made mostly from PVC, there is a chip inserted which contains a microprocessor.Side channel attacks are trying to use the leaking information from the physical implementation of the system while processing the cryptographic algorithm. The attacker is trying to use the leaking sensitive information because under certain circumstances it can be dependent on the input data. The theoretical part is devoted to description of smart cards, their types and their safety. It describes the classification of attacks on smart cards and includes the overview of selected cryptographic algorithms used in smart cards. It also describes selected physical and logical attacks and the most frequent side channel attacks. The thesis furthermore describes possibilities of measuring the voltage-current side channel. The practical part deals with used software and hardware. This section is devoted to the measurement of power specification of smart cards and to the analysis of processed information, using the oscilloscope and workstation with AD 622 card and Simulink development environment.
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Increasing the efficiency of the handover in real network environment
Michalec, Richard ; Sobotka, Jiří (referee) ; Vajsar, Pavel (advisor)
The aim of this work is to study methods of handover used in WiMAX and WLAN networks, next suggest the posibility of simulation methods for WLAN handover in the simulation environment OPNET Modeler. This work is focused primarily on obtaining the information about neighboring AP and subsequent selection of a new AP using such information. The work describes in detail each processes solutions that are used to implement newscanning methods
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Home security system - power supply
Sobotka, Jiří ; Bradáč, Zdeněk (referee) ; Fiedler, Petr (advisor)
The main goal of this bachelor thesis was to name all the requirements connected with alarm system power supply and to suggest a concept of a source with reserve lead-acid accumulator. Furthermore there is documentation of realisation of functional specimen. In this thesis there is a concept of stabilized power supply suppliyng the EZS components. The charging circuit for the lead-acid accumulator, connectors signaling the presence of system voltage and indicating connectors for low accumulator voltage. In the concept you can also find accumulator disconnector in case of low accumulator voltage ( liquidation accumulator voltage ). There is also piezobuzzer for the alert put on by switchboard station. The power supply was designed on the printed circuit board (PCB) and together with leadacid accumulator and transformator were placed in one box to which the supply cable is drawn.
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Analysis of data transfer security issues at particular OSI model layers
Kňazovický, Pavel ; Růčka, Lukáš (referee) ; Sobotka, Jiří (advisor)
The aim of this Bachelor's thesis is the analysis of secured data transfer protocols. The very first part is dedicated to the short description of the reference model ISO/OSI. The second one is focused to the secured protocols at particular layers of ISO/OSI model, of which SSL/TLS protocol is closely analysed in the third part. The last part is about often used attacks in the area of computer networks and their services and the basic protection against them is also mentioned.
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Diffie-Hellman key exchange protocol
Člupek, Vlastimil ; Burda, Karel (referee) ; Sobotka, Jiří (advisor)
In this bachelor's thesis there is explained principle of cryptography, encryption methods and primarily cryptographic protocol key exchange Diffie-Hellman. There is described key exchange process via public channel. Problem of discrete logarithm. Attack "Man in the middle" on this protocol and protection against this attack. Subsequently there is described a newer version of this protocol, which work's with elliptic curves. Its name is Elliptic Curve Diffie-Hellman (ECDH). In this protocol there is hereinafter described a procedure of calculate a secret point on elliptic curve. Problem of Elliptic discrete logarithm. Attack "Man in the middle" on protocol ECDH and protection against this attack. Furthermore this thesis deals with analyzing mutual compatibility between protocol DH and ECDH and its possible solutions.
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