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Discussions on News Articles on social Networks
Rozsypalová, Blanka ; Charvát, Jakub (advisor) ; Jirků, Jan (referee)
The thesis focuses on discussions under news articles shared by news servers on the social network Facebook. The aim of this work is to summarize the existing understanding of the topic. Therefore, theoretical concepts connected to the topic are summarized. The thesis focuses on communication, online communication and the presence of news servers on social networks, as well as on the topic of anonymity on social networks and how anonymity can affect discussions. A chapter of the thesis focuses on the spiral of silence and its possible occurrence in discussions. Further, the thesis focuses on the freedom of speech as well as the new ways social networks are trying to fight disinformation and hate online. The empirical part focuses on how Facebook users view the use of social networks by news servers. Another part of the thesis focuses on a group of volunteers called #jsmetu. This group tries to make sure discussions are factual and are free from personal attacks and vulgarity. Three discussions are analysed - discussions #jsmetu took part in. The thesis investigates the influence #jsmetu has on discussions. Due to the topic of the thesis being a very current one, the thesis suggests more areas for further research.
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Parental substance use in connection with the occurrence of risky behavior in children aged 11-15 in the Czech Republic participating in a randomized controlled prevention trial.
Vacek, Jaroslav ; Gabrhelík, Roman (advisor) ; Charvát, Miroslav (referee) ; Kachlík, Petr (referee)
Background: Despite a slight decline in the prevalence of substance use among adolescents in last years, there is a constant need for effective, available and well-targeted preventive interventions. Children of parents with substance use experiences are considered to be more endangered. Although the quality and availability of universal prevention programs has improved, their effectiveness is not usually systematically verified, moreover, the impact on children of parents with substance use experiences is unknown. The Unplugged preventive intervention was supplemented by nPrevention booster sessions in order to support its research-proven preventive impact. Aims: The main objective was to evaluate the effect of Unplugged and nPrevention programs combination (Un+nP) after 24 months in comparison with Unplugged program (Un) alone and control in respect of the substance use experience in parents. The secondary objective was to test the reliability of anonymous self-generated identification code (SGIC) and the process of matching children's questionnaires between waves of data collection and with parents' questionnaires. Methods: A cluster randomized, controlled, 3-arm, prospective, school-based prevention trial was conducted between years 2013 and 2017 to evaluate the Unplugged (implemented in the 6th...
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Free speech on the Internet and censorship as a way to protectusers' privacy
Brišová, Jana ; Moravec, Václav (advisor) ; Osvaldová, Barbora (referee)
The aim of this bachelor thesis is to provide a complex analysis of free speech on the internet, violation of this right and ways how to protect own privacy in cyberspace. It is based on a theoretical exploration of protection of free speech, right to privacy and collision of these rights. Based on this theoretical analysis this thesis seeks to provide a comprehensive analysis of the cyberspace as a space enabling free speech as well as violating the right to privacy. This thesis also explores the responsiveness of the Internet to the users' demands on privacy, violations of the right to freedom of expression, and censorship of the Internet, as demonstrated by the case studies of countries taking these steps. This is followed by a research of ways to circumvent Internet censorship, including the possibility of anonymity on the Internet. Anonymity is also discussed as a tool to protect privacy as well as source of dangers.
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Implementation of cryptographic protocols on smart cards
Moravanský, Michal ; Hajný, Jan (referee) ; Dzurenda, Petr (advisor)
The bachelor thesis is focused on cryptographic schemes using Attribute-Based Credentials, which try to minimize the negative impact on the protection of a user's privacy when using authentication systems. The aim of the bachelor's thesis was the implementation of two specified schemes on smart cards as a device with limited performance. Schemes differ only in the ability to revoke user. The practical part of this paper contains the analysis and selection of smart card platform and cryptographic libraries depending on performance. The work also describes the architecture of both schemes and individual protocols, including ongoing communication. The implementation of the Attribute-Based Credentials scheme was performed on a programmable smart card Multos (user side) and Raspberry Pi 2 (issuer and verifier side). The time complexity of the selected algorithms was also compared. In the end, the dependencies affecting the resulting efficiency and speed of the protocol were formulated.
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Anonymity in P2P Networks
Brunai, Adam ; Malinka, Kamil (referee) ; Barabas, Maroš (advisor)
Freedom of speech and the right to privacy are maybe the most important elements of a modern society, yet the rights are often violated. This fact was the main reason for writing this thesis covering P2P network models, anonymity, censorship resistance and their use in real P2P networks and publishing systems. We discuss their effectiveness and suitability for specific purposes, but also the security considerations of their use. The second part of this thesis presents the LSPP publishing protocol, which is an library implementation of an anonymous censorship resistant P2P network. Finally, we analyze the proposed protocol and compare it with existing solutions.
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Cryptographic Protection of Digital Identity
Dzurenda, Petr ; Švenda,, Petr (referee) ; Castella-Roca, Jordi (referee) ; Hajný, Jan (advisor)
Dizertační práce se zabývá kryptografickými schématy zvyšující ochranu soukromí uživatelů v systémech řízení přístupu a sběru dat. V současnosti jsou systémy fyzického řízení přístupu na bázi čipových karet využívány téměř dennodenně většinou z nás, například v zaměstnání, ve veřejné dopravě a v hotelech. Tyto systémy však stále neposkytují dostatečnou kryptografickou ochranu a tedy bezpečnost. Uživatelské identifikátory a klíče lze snadno odposlechnout a padělat. Funkce, které by zajišťovaly ochranu soukromí uživatele, téměř vždy chybí. Proto je zde reálné riziko možného sledovaní lidí, jejich pohybu a chovaní. Poskytovatelé služeb nebo případní útočníci, kteří odposlouchávají komunikaci, mohou vytvářet profily uživatelů, ví, co dělají, kde se pohybují a o co se zajímají. Za účelem zlepšení tohoto stavu jsme navrhli čtyři nová kryptografická schémata založená na efektivních důkazech s nulovou znalostí a kryptografii eliptických křivek. Konkrétně dizertační práce prezentuje tři nová autentizační schémata pro využití v systémech řízení přístupu a jedno nové schéma pro využití v systémech sběru dat. První schéma využívá distribuovaný autentizační přístup vyžadující spolupráci více RFID prvků v autentizačním procesu. Tato vlastnost je výhodná zvláště v případech řízení přístupu do nebezpečných prostor, kdy pro povolení přístupu uživatele je nezbytné, aby byl uživatel vybaven ochrannými pomůckami (se zabudovanými RFID prvky). Další dvě schémata jsou založena na atributovém způsobu ověření, tj. schémata umožňují anonymně prokázat vlastnictví atributů uživatele, jako je věk, občanství a pohlaví. Zatím co jedno schéma implementuje efektivní revokační a identifikační mechanismy, druhé schéma poskytuje nejrychlejší verifikaci držení uživatelských atributů ze všech současných řešení. Poslední, čtvrté schéma reprezentuje schéma krátkého skupinového podpisu pro scénář sběru dat. Schémata sběru dat se používají pro bezpečný a spolehlivý přenos dat ze vzdálených uzlů do řídící jednotky. S rostoucím významem chytrých měřičů v energetice, inteligentních zařízení v domácnostech a rozličných senzorových sítí, se potřeba bezpečných systémů sběru dat stává velmi naléhavou. Tato schémata musí podporovat nejen standardní bezpečnostní funkce, jako je důvěrnost a autentičnost přenášených dat, ale také funkce nové, jako je silná ochrana soukromí a identity uživatele či identifikace škodlivých uživatelů. Navržená schémata jsou prokazatelně bezpečná a nabízí celou řadu funkcí rozšiřující ochranu soukromí a identity uživatele, jmenovitě se pak jedná o zajištění anonymity, nesledovatelnosti a nespojitelnosti jednotlivých relací uživatele. Kromě úplné kryptografické specifikace a bezpečnostní analýzy navržených schémat, obsahuje tato práce také výsledky měření implementací jednotlivých schémat na v současnosti nejpoužívanějších zařízeních v oblasti řízení přístupu a sběru dat.
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User and Device Metadata Collection from the Darkweb
Gula, Ján ; Matoušek, Petr (referee) ; Veselý, Vladimír (advisor)
This bachelor's thesis solves the problem of anonymization on the Internet, that is widely used for dealing with illegal substances. This problem drives law enforcement agencies to be interested in web pages that represent markets with forbidden content which are hidden behind anonymity networks. My goal is to focus on the biggest markets with such content and to gather as much information as possible about subjects that posture on similar types of web pages either as sellers or as buyers. I have resolved the given problem by choosing the most impactful markets according to the number of users signed in. I have become one of the users and applied algorithms for data scraping to get information from web pages into a structured form that is more suitable for a deeper analysis. The results of this thesis will help law enforcement agencies with the analysis of metadata of users that commit illegal activities as they will not have to manually search through the illegal markets, and they will have all available data summed up in a structured form in a database. Unifying data into a structured form will help speeding up the investigation and address the biggest drug sellers.
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Cryptographic currency Bitcoin
ALEŠ, Petr
The bachelor thesis deals with cryptographic currency Bitcoin. It describes the origin, development and current state of the currency. It also outlines the basic principles on which the currency works from a technical standpoint and examines the main advantages and disadvantages of the system compared to the classical currencies. The practical part discusses the issue of security and anonymity in the system. The questionnaire identifies the current state of Bitcon awareness and what features are considered to be the greatest disadvantages from a user perspective. This is followed by an analysis of potential system security intrusions, along with an analysis of several actually performed successful attacks.
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Darknet networks as a way of protecting internet users' privacy
Plevný, Marek ; Sigmund, Tomáš (advisor) ; Čermák, Radim (referee)
In this age when information technologies became inseparable parts of our lives we can hardly imagine for example living without internet. There is a phenomenon connected with internet and that is large scale collection of data about internet users and their activities. Because of this fact, it is important to protect our internet privacy as a very important aspect of our lives. This work examines large scale collection of data about users internet activities. During this work, different methods and reasons for this largescale data collection are examined. Later, different ways how internet users are protected by law or how they can protect themselves are examined. One of the ways how internet users can protect their internet privacy is by using so-called anonymizing networks connected with a phenomenon called Darknet. This work examines if it is possible by ordinary internet users to adapt this method of internet privacy protection.
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