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Digital certificates
Svačina, Ondřej ; Vokoun, Tomáš (advisor) ; Daniel, Daniel (referee)
This thesis is focused on the topic of digital certificates for secure communication. First of all, methods of authentication and cryptography are analyzed as a starting point. Furthermore, the thesis describes communication protocols for secure connection HTTPS and SSL/TLS, the importance of certification authorities and their characteristics. It devotes the biggest part of attention to digital certificates as such.
Practical part introduces available certification authorities, including practical creation of the new certification authority and certificate. This untrusted certificate has become the key element of the questionnaire survey, which aim is to analyze knowledge level of users about secure connection through trusted certificates. After the analysis, interpretation of obtained data and verification of selected hypothesis, recommendations for domain owners, who are planning to use HTTPS, were proposed.
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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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Secured access for web applications
Humpolík, Jan ; Pelka, Tomáš (referee) ; Doležel, Radek (advisor)
This thesis mainly concerns often neglected security part of each web application, but also secure access users themselves. Describes theoretically and practically modern security technology, on a web application being tested and shows a possible way of defense. Gives instructions for installing its own web server.
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Cryptography on an embedded platform
Korenčiak, Peter ; Hynčica, Ondřej (referee) ; Fiedler, Petr (advisor)
This bachelor thesis deals with adjusting parts of the public domain cryptographic library LibTomCrypt so that it can be used on an embedded platform Rabbit 3000. The hash functions MD5, SHA-1 and RIPEMD-128, the Blowfish cipher and CBC block cipher mode have been successfully ported to this platform. These algorithms have been analysed by measuring of the exectution time for the computational power requirements, especially with regard to the length of the input data. The abovementioned hash functions showed non-linear relationship between the execution time and the length of input, the graph of which is like that of a step function. The non-existence of the relationship to the data values was confirmed. The measurements with Blowfish cipher in CBC block cipher mode showed that inicialization of cipher is time consuming (it lasted almost one second on the hardware used) and that it does not depend on the keysize or length of input. The encryption and decryption itself showed a linear relationship to input data length. In the scope of this thesis there was also verification of correct function of SSL/TLS library from the producer of Rabbit microprocessor by creating a HTTPS server and verifying that secure connection with the web browser has been established. The library worked correctly according to manual without any significant problems.
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Secure peer-to-peer communication system
Eliáš, Luboš ; Koutný, Martin (referee) ; Cvrk, Lubomír (advisor)
The main aim of this master's thesis is to implement a common, secure and peer-to-peer communication system. The system has ability to automatically establish and run a secure end-to-end connection. It has this ability even if a network address translator is in the way to the destination system, without need of any explicit configuration of this translator. The security procedures of this system are in a transparent manner masked from individual applications, which had to solve this challenge in their own way. A responsibility for a security is delegate to an application-independent subsystem working within the core of an operating system. The security of this subsystem is based on capturing the outbound and inbound IP packets and their authentication and encryption. The system was successfully implemented in MS Windows XP operating system, in programming language C++. Transfer rate of communication tunnel in different network bandwidth speeds was measured. Result shows, that in the case of use the system on standard PC sold nowadays is practically no decrease of the transfer rate in comparison to a common channel.
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State of internetbanking and its security in the Czech republic and the rest of the world
Havlín, Petr ; Matuštík, Ondřej (advisor) ; Exnarová, Anna (referee)
Práce se zabývá analýzou stavu služeb internetového bankovnictví v ČR a ve světě. Seznamuje čtenáře s bezpečnostními prvky, které jsou v tomto odvětví využívány a s rozsahem funkcí, které aplikace jednotlivých bank nabízejí. Jsou popsány hlavní způsoby, které jsou použity pro šifrování přenosu dat po nezabezpečené síti Internet. Obsaženy jsou jak metody založené na symetrických, tak asymetrických klíčích. Pozornost je věnována i některým typům útoků, které mohou být proti šifrám vedeny. Práce se také věnuje možnostem bezpečné identifikace uživatelů. Jsou popsána statická hesla, jednorázová hesla, klientské certifikáty a systémy založené na principu challenge-response. Analyzována je jejich vhodnost a odolnost proti praktikám typu ?Phishing?, ?Pharming?, ?Vishing? nebo útok typu ?Man in the middle?. Zmíněno je i dodatečné zabezpečení prováděných transakcí. ?Bezpečnostní politika jednotlivce? doporučuje pravidla, která by měl dodržovat každý zodpovědný klient. Naznačeny jsou i technologie, které by podstatně zvýšily ochranu před neoprávněným vniknutím do systému a které by také umožnily odhalení podvodných transakcí v reálném čase.
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