National Repository of Grey Literature 25 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
A portal to support the teaching of applied cryptography
Vojáčková, Veronika ; Sikora, Marek (referee) ; Zeman, Václav (advisor)
Cryptography has a rich history, ranging from ancient civilizations to modern times, ensuring confidentiality and security has always played a very important role. In order to understand these algorithms, however, it is necessary to understand the basics of this issue, which can be a very difficult task without comprehensive resources. The thesis first examines web portals dealing with cryptography on the Czech and foreign Internet. Next, it compiles all the necessary knowledge for the subject of applied cryptography. As part of the work, a web portal is created bringing together the necessary information to support teaching along with a practical demonstration of algorithms and their use in the Python programming language.
Webpage as digital evidence
Rezek, Jan ; Míšek, Jakub (referee) ; Harašta, Jakub (advisor)
This bachelor’s thesis deals with the issue of securing websites as electronic evidence. It focuses on the analysis of legal regulations and decision-making practice concerning electronic evidence, and on this basis identifies the requirements for its preservation and securing. The thesis also examines the role of hashing functions in maintaining the integrity and authenticity of such evidence. As a result, a tool is designed and implemented for the retrieval and preservation of evidence-quality web content that is consistent with the identified requirements.
Security and usability of standard has hfunctions, in particular MD-5, SHA-1 and SHA-2
Galaczová, Barbora ; Tůma, Jiří (advisor) ; Joščák, Daniel (referee)
Title: Security and usability of standard hash functions, in particular MD-5, SHA-1 and SHA-2 Author: Galaczová Barbora Department: Department of Algebra Supervisor: Doc. RNDr. Tůma Jiří, DrSc., Department of Algebra Consultant: Ing. Budiš Petr, Ph.D. Abstract: In the present work we try to digestedly describe standard hash functions, in particular MD-5, SHA-1 and SHA-2. We describe resume of existing attacks on these hash functions. We closely focused on MD-5 collision attacks, because the other hash function collision attacks result from these. Next we describe posibilities of practical usage of hash function collisions, in particular into the qualified certificates area and possible threats. At the end to the present work we describe new hash functions, which could replace current hash functions. This work also contains software to calculate MD-5 hash and search it`s collisions. The software is based on method invented by Czech cryptoanalytist Vlastimil Klíma. Keywords: hash function, collision, qualified certificate, security.
Binární znaménkové reprezentace celých čísel v kryptoanalýze hashovacích funkcí
Vábek, Jiří ; Tůma, Jiří (advisor) ; Kůrka, Petr (referee) ; Holub, Štěpán (referee)
Title: Binary Signed Digit Representations of Integers in Cryptanalysis of Hash Functions Author: Jiří Vábek Department: Department of Algebra Supervisor: doc. RNDr. Jiří Tůma, DrSc., Department of Algebra Abstract: The work summarizes two main papers, A New Type of 2-block Colli- sions in MD5 and On the Number of Binary Signed Digit Representations of a Given Weight, while containing also the wider introduction to the topic of crypt- analysis of MD5 and binary signed digit representations (BSDR's). In the first paper we have implemented and applied Stevens algorithm to the newly proposed initial message differences and constructed a new type of collisions in MD5. In the second paper we have introduced and proved a new improved bound for the number of optimal BSDR's and also a new recursive bound for the number of BSDR's of a given integer with a given overweight. In addition to the results in mentioned papers, the generalized result is stated with the new bound for the number of optimal D-representations of natural numbers with D = {0, 1, 3}. Keywords: hash function, MD5, binary signed digit representation (BSDR), non- adjacent form (NAF) 1
Evolutionary Design of Hash Functions Using Grammatical Evolution
Freiberg, Adam ; Bidlo, Michal (referee) ; Sekanina, Lukáš (advisor)
Grammatical evolution allows us to automate creating solutions to various problems in arbitrary programming languages. This thesis takes advantage of this method to experimentally generate new hash functions focused specifically on network flow hashing. Subsequently, these newly generated functions are compared with existing state-of-the-art hash functions, created by experts in the field.
Evolutionary design and optimization of components used in high-speed computer networks
Grochol, David ; Sekaj, Ivan (referee) ; Jašek, Roman (referee) ; Sekanina, Lukáš (advisor)
Výzkum prezentovaný v této práci je zaměřen na evoluční optimalizaci vybraných komponent síťových aplikací určených pro monitorovací systémy vysokorychlostních sítí. Práce začíná studiem současných monitorovacích systémů. Jako experimentální platforma byl zvolen systém SDM (Software Defined Monitoring). Detailně bylo analyzováno zpracování síťového provozu, protože tvoří důležitou součást všech monitorovacích systémů. Jako demonstrační komponenty pro aplikaci optimálních technik navržených v této práci byly zvoleny klasifikátor aplikačních protokolů a hashovací funkce pro síťové toky. Evoluční algoritmy byly zkoumány s ohledem nejen na optimalizaci kvality zpracování dat danou síťovou komponentou, ale i na čas potřebný pro výpočet dané komponenty. Byly zkoumány jednokriteriální i vícekriteriální varianty evolučních algoritmů.     Byl navržen nový přístup ke klasifikaci aplikačních protokolů. Přesná i aproximativní verze klasifikátoru byla optimalizována pomocí CGP (Kartézské Genetické Programování). Bylo dosaženo výrazné redukce zdrojů a zpoždění v FPGA (Programovatelné Logické Pole) oproti neoptimalizované verzi. Speciální síťové hashovací funkce byly navrženy pomocí paralelní verze LGP (Lineární Genetické Programování). Tyto hashovací funkce vykazují lepší funkcionalitu oproti moderním hashovacím funkcím. S využitím vícekriteriální optimalizace byly vylepšeny výsledky původní jednokriteriální verze LGP. Paralelní zřetězené verze hashovacích funkcí byly implementovány v FPGA a vyhodnoceny za účelem hashování síťových toků. Nová rekonfigurovatelná hashovací funkce byla navržena jako kombinace vybraných hashovacích funkcí.  Velmi konkurenceschopná obecná hashovací funkce byla rovněž navržena pomocí multikriteriální verze LGP a její funkčnosti byla ověřena na reálných datových sadách v provedených studiích. Vícekriteriální přístup produkuje mírně lepší řešení než jednokriteriální LGP. Také se potvrdilo, že obecné implementace LGP a CGP jsou použitelné pro automatizovaný návrh a optimalizaci vybraných síťových komponent. Je však důležité zvládnout vícekriteriální povahu problému a urychlit časově kritické operace GP
Electronic Mail Room of the BUT
Beran, Martin ; Křena, Bohuslav (referee) ; Marušinec, Jaromír (advisor)
This dissertation thesis attends to problems of electronic registry for VUT. It deals with the principal of electronic registry functioning, electronic signature and it compares offer of the commercial registries. It goes in for the proposal and implementation of the electronic registry for VUT. Since the using of the e- registry on all public service Office was legalized the people can avoid long queues and the employees are avoided from the stress before dead lines. By the communication through the electronic registry is very important the electronical signature. It is almost a full-valued and lawful alternative to the physical signature. For its safety and utility this system employes asymmetric codes and hash algorithm. Presently in many states, where the electronical signature is legalized it is used together with standard X 509 which defines the format of certificates, organization and action of certification authorities. The certification autority ensures safe connection of the person and general key for using of the electronical signature.
Binární znaménkové reprezentace celých čísel v kryptoanalýze hashovacích funkcí
Vábek, Jiří ; Tůma, Jiří (advisor) ; Kůrka, Petr (referee) ; Holub, Štěpán (referee)
Title: Binary Signed Digit Representations of Integers in Cryptanalysis of Hash Functions Author: Jiří Vábek Department: Department of Algebra Supervisor: doc. RNDr. Jiří Tůma, DrSc., Department of Algebra Abstract: The work summarizes two main papers, A New Type of 2-block Colli- sions in MD5 and On the Number of Binary Signed Digit Representations of a Given Weight, while containing also the wider introduction to the topic of crypt- analysis of MD5 and binary signed digit representations (BSDR's). In the first paper we have implemented and applied Stevens algorithm to the newly proposed initial message differences and constructed a new type of collisions in MD5. In the second paper we have introduced and proved a new improved bound for the number of optimal BSDR's and also a new recursive bound for the number of BSDR's of a given integer with a given overweight. In addition to the results in mentioned papers, the generalized result is stated with the new bound for the number of optimal D-representations of natural numbers with D = {0, 1, 3}. Keywords: hash function, MD5, binary signed digit representation (BSDR), non- adjacent form (NAF) 1
Electronic money
Gescheidt, Daniel ; Komosný, Dan (referee) ; Zeman, Václav (advisor)
In this bachelor thesis are described electronic money systems, which uses cryptography techniques such as symmetric and asymmetric ciphers, digital sign and hash function. Describing those techniques is crucial for understanding how electronic money systems works. Then three electronic money systems from Czech republic are briefly described.
Security and usability of standard has hfunctions, in particular MD-5, SHA-1 and SHA-2
Galaczová, Barbora ; Tůma, Jiří (advisor) ; Joščák, Daniel (referee)
Title: Security and usability of standard hash functions, in particular MD-5, SHA-1 and SHA-2 Author: Galaczová Barbora Department: Department of Algebra Supervisor: Doc. RNDr. Tůma Jiří, DrSc., Department of Algebra Consultant: Ing. Budiš Petr, Ph.D. Abstract: In the present work we try to digestedly describe standard hash functions, in particular MD-5, SHA-1 and SHA-2. We describe resume of existing attacks on these hash functions. We closely focused on MD-5 collision attacks, because the other hash function collision attacks result from these. Next we describe posibilities of practical usage of hash function collisions, in particular into the qualified certificates area and possible threats. At the end to the present work we describe new hash functions, which could replace current hash functions. This work also contains software to calculate MD-5 hash and search it`s collisions. The software is based on method invented by Czech cryptoanalytist Vlastimil Klíma. Keywords: hash function, collision, qualified certificate, security.

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