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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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Side channels in cryptography
Budík, Lukáš ; Sobotka, Jiří (referee) ; Martinásek, Zdeněk (advisor)
This work deals with a problem called sidelong cannals in cryptografy. First part describes basic segmentation of cryptografy branch. In addition to this the document mentions some requirements for cryptology system from security angle. In another section basic algorithms and protocols are described which are used in cryptology. Main part of this work is aimed at sidelong cannals problem. Conclusion of this task demonstrates an attack by time-side canal to algorithm RSA.
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Distributed systems for cryptoanalysis
Vašek, Jiří ; Trzos, Michal (referee) ; Sobotka, Jiří (advisor)
This thesis should introduce a reader with basic objectives of parallel computing followed by distributed systems. The thesis is also aimed at description of cryptographic attacks. The main point should be to obtain theoretic information for design of distributed system for cryptoanalysis.
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Side channels
Kolařík, Jan ; Sobotka, Jiří (referee) ; Martinásek, Zdeněk (advisor)
This Master Thesis deals with the side channels, AES encryption algorithm and the use of neural networks to obtain the encryption key. The first part of this work is focused on the basics of cryptography and attacks on cryptographic module. The second part is focused on electromagnetic side channel attack on PIC16F84A microcontroller with embedded AES algorithm. In this section, the Master Thesis tries to analyze electromagnetic emissions of operation S-Box in AES algorithm and try to find sensitive information to use neural network identify encryption key of the AES algorithm. In conclusion is described the software source code to determine the encryption key, summarized results and discussed ways to defend against electromagnetic side channel attack.
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Multiaplication smart cards
Meluzín, Ivo ; Malina, Lukáš (referee) ; Sobotka, Jiří (advisor)
The goal of the first part of the thesis is to describe the options of wide usage of chip cards in different segments of our life. Consequently it is necessary to mention hardware and software equipment of smart card, its communication with terminal and data security. In this thesis we focus on Java Card environment in which we will try to create two applications, one for electronic purse and the second for user identification. Basically, we need to mention multiapplicational rules of sharing data and objects. At the end of the thesis we are focusing on the possibility of mutual interference between the applications and on protection against attacks. Also future applications of this technology are described.
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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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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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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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Distributed systems for cryptoanalysys
Zelinka, Miloslav ; Martinásek, Zdeněk (referee) ; Sobotka, Jiří (advisor)
This work deals with crytpoanalysis, calculation performance and its distribution. It describes the methods of distributing the calculation performance for the needs of crypto analysis. Further it focuses on other methods allowing the speed increasing in breaking the cryptographic algorithms especially by means of the hash functions. The work explains the relatively new term of cloud computing and its consecutive use in cryptography. The examples of its practical utilisation follow. Also this work deals with possibility how to use grid computing for needs of cryptoanalysis. At last part of this work is system design using „cloud computing“ for breaking access password.
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