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Decentralized communication tool with anonymity guarantee
Legéň, Michal ; Burget, Radim (oponent) ; Malý, Jan (vedoucí práce)
Anonymity on the internet is becoming a actuall issue nowadays. There are several tools, that can be used to monitor user's activity and it can lead to lose privacy of users. The aim of this master's thesis is to describe different ways of working anonymous systems, especially the method called Onion Routing. The introduction of this work is devoted to the description of this method together with asymmetric cryptosystem RSA. The second part belongs to basics of socket programming and to the implementation of anonymous system in programming language C++. The final part is focussed on analysis of system in terms of security and time complexity. The conditions of anonymity and decentralization are accomplished. There is no presence of central server in the system and the management is handled by signalling messages.
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Implementation and testing of MD5 hash algorithm
Legéň, Michal ; Kacálek, Jan (oponent) ; Malý, Jan (vedoucí práce)
Hash functions are one of basic structural components of modern cryptography. Their task is to create unique bit order for entry information called message digests. This way the inevitable integrity of information is secured because data transferring via different transfer media may be altered during the transfer. They provide a possibility of fast and effective encryption of passwords because of one-way as well. The aim of this bachelor’s thesis is to analyse one of the most well-known hash functions MD5, to implement it in programming language, to analyse its security risks and to try to use practical exhibitions to the benefit of an attacker. The bachelor’s thesis is presenting theoretical and practical part on Implementation and testing of MD5 hash algorithm. The introduction of the work is devoted to the basics of cryptography, to explanation of the concept of hash function and its basic attributes. The chapter 3 is focussed on the analysis of algorithm MD5 itself. The following part describes its implementation in programming language C++. The last two parts are about problems of security and weak sides of hash algorithm MD5. On the basic of existance of first order collisions, there is in practical demonstration presented creating two different programmes with the same message digest. The final part belongs to description of implementations of attacks on one-way algorithm MD5 and comparisons of their time possibilities during getting original information on the basis of their message digests.
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Implementation and testing of MD5 hash algorithm
Legéň, Michal ; Kacálek, Jan (oponent) ; Malý, Jan (vedoucí práce)
Hash functions are one of basic structural components of modern cryptography. Their task is to create unique bit order for entry information called message digests. This way the inevitable integrity of information is secured because data transferring via different transfer media may be altered during the transfer. They provide a possibility of fast and effective encryption of passwords because of one-way as well. The aim of this bachelor’s thesis is to analyse one of the most well-known hash functions MD5, to implement it in programming language, to analyse its security risks and to try to use practical exhibitions to the benefit of an attacker. The bachelor’s thesis is presenting theoretical and practical part on Implementation and testing of MD5 hash algorithm. The introduction of the work is devoted to the basics of cryptography, to explanation of the concept of hash function and its basic attributes. The chapter 3 is focussed on the analysis of algorithm MD5 itself. The following part describes its implementation in programming language C++. The last two parts are about problems of security and weak sides of hash algorithm MD5. On the basic of existance of first order collisions, there is in practical demonstration presented creating two different programmes with the same message digest. The final part belongs to description of implementations of attacks on one-way algorithm MD5 and comparisons of their time possibilities during getting original information on the basis of their message digests.
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Decentralized communication tool with anonymity guarantee
Legéň, Michal ; Burget, Radim (oponent) ; Malý, Jan (vedoucí práce)
Anonymity on the internet is becoming a actuall issue nowadays. There are several tools, that can be used to monitor user's activity and it can lead to lose privacy of users. The aim of this master's thesis is to describe different ways of working anonymous systems, especially the method called Onion Routing. The introduction of this work is devoted to the description of this method together with asymmetric cryptosystem RSA. The second part belongs to basics of socket programming and to the implementation of anonymous system in programming language C++. The final part is focussed on analysis of system in terms of security and time complexity. The conditions of anonymity and decentralization are accomplished. There is no presence of central server in the system and the management is handled by signalling messages.
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