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Selected encyption methods
MILICHOVSKÁ, Eva
The aim of this thesis is introduction into issues of classical cryptology from its beginnings in the antiquity to the half of the 20th century. Further, the division of basic ciphers on substitutional and transpositional ones is stated. Only the most important ciphers were chosen from the large number and demonstrations of decipherment were stated here, too. Then, the way of decipherment of Vigen?r´s "indecipherable" cipher is showed here.
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Invisible watermarking of digital signals
Pacura, Dávid ; Horák, Karel (referee) ; Petyovský, Petr (advisor)
Cílem téhle práce je navrhnutí nových technik pro robustní neviditelné značení digitálních signálů. Nejdříve je prezentován současný stav tohoto odvětví a dostupné softwarové řešení. Poté následuje návrh několika algoritmů pro neviditelné značení, přičemž každý z nich je založen na jiném principu. Dále je připravena sada digitálních testovacích signálů společně s testovacím softwarem pro otestování navržených řešení a jejích porovnání s vybraným dostupným softwarem. Poté následuje srovnání naměřených výsledků, výkonu a jejích diskuze.
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Steganography
Podhorský, Jiří ; Kubíček, Radek (referee) ; Zemčík, Pavel (advisor)
This bachelor project focuses on steganography and presents new modifications of known metods steganography and their implementation. It also presents implementation of adaptive metod Neighbours, for comparison. Both of the metods are based on the "Least Significant Bit" exploitation. It is also demonstrated that newly proposed modification can be used in other metods of steganography. The purpose of proposed method is to encode a secret information into the digital image so that the information is not easily detectable.
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Hiding Data in Computer Networks
Hrebíček, Martin ; Halfar, Patrik (referee) ; Polčák, Libor (advisor)
This diploma thesis deals with hiding data in the Internet traffic. It contains a description of the law interception. Various possibilities of hiding data are mentioned. The practical part of this thesis consists of an application that hides the data of HTTP and HTTPS protocols in a fake VoIP call. The application consists of two parts: a client and a server. Data transmitted between the client and the server parts are masked as multimedia data of the VoIP call. When a user or Internet server does not transmit any data, random data are transmitted between client and server parts in order to simulate the VoIP call. Then, the thesis focuses on detection of the attack.
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A Hidden GNU/Linux File System
Pavlásek, Martin ; Smrčka, Aleš (referee) ; Lengál, Ondřej (advisor)
Some sensitive data need such a way of hiding that hides not only the content of the data but its preserve itself. The goal of this Bachelor's thesis is to create a file system that enables hiding of files with sensitive data to other files. This text contains an overview of principles used in current file systems and a description of the structure and use of the FUSE technology. Further, the work describes the design of a filesystem that hides files into ID3 tags of MP3 music files and it's implementation in C++. The created filesystem is experimentally assessed and evaluated.
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Software for data hiding in image files
Morkus, Filip ; Říha, Kamil (referee) ; Burda, Karel (advisor)
In my master's thesis I start fromthedescriptionofthebasics and thebeginningsofsteganography, itsmethods and purposes. Detaileddescriptionof BMP fileswithhidden data follows. A filestructureisanalysedintothesmallestdetails to avoiddamagingfilewhilehiding. At thesametime to make profit oftheinformationincluded in a fileheader in the most effectiveway. Anotheraimwas to explain a principalofsteganographicalmethoditself, usedforhiding data into BMP file. Based on these findings, a programmeconceptwasdesigned and consequentlythatprogrammewas made. Itcarriesoutthehiding and revealing data intothe image files. Directionsfor use are made to thisprogramme and thereisalso a demo ofthefeaturesdescribingeach step. At the end ofmymaster's thesis anattentionispaid to thoseinfluencesthatcanbelimitingforthismethod. Exceeding these limitswouldlead to breakingthesteganographicalmethod, whichmeansrevealingthehidden data.
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