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.

The internet is one of the most widely used mediums for communication in modern society and it has become an everyday necessity for many. It is therefore of utmost importance that it remains as secure as possible. SSL and TLS are the backbones of internet security and an integral part of these technologies are the certificates used. Certificate authorities (CAs) can issue certificates that validate that domains are who they claim to be. If a user trusts a CA they can in turn also trust domains that have been validated by them. CAs can in turn trust other CAs and this, in turn, creates a chain of trust called a certificate chain. In this thesis, the structure of these certificate chains is analysed and a longitudinal dataset is created. The analysis looks at how the certificate chains have changed over time and puts extra focus on the domains of big tech companies. The dataset created can also be used for further analysis in the future and will be a useful tool in the examination of historical certificate chains. Our findings show that the certificate chains of the domains studied do change over time; both their structure and the lengths of them vary noticeably. Most of the observed domains show a decrease in average chain length between the years of 2013 and 2020 and the structure of the chains vary significantly over the years.

Syftet med denna studie är att undersöka hur svensklärare och SVA-lärare i lågstadiet beskriver sitt arbete och samarbete för att gynna SVA-elever i svenskundervisningen. Studien tar teoretisk utgångspunkt i det sociokulturella perspektivet och kollegialt lärande. Den metod som användes vid insamling av data var semistrukturerad intervju som bearbetades med hjälp av innehållsanalys. Resultatet tyder på att svensklärare och SVA-lärare arbetar på likartade sätt för att gynna SVA-elever i deras språkutveckling. Lärarna beskriver att de förklarar och förenklar ord samt använder digitala verktyg och bildstöd för att göra innehållet av lektionerna tydligt för SVA-eleverna. Resultatet visar även att samarbete mellan svensk- och SVA-lärarna om lektionerna och kontakt om SVA-elevernas språkutveckling varierar. Slutsatserna av studien är att (1) digitala verktyg och bildstöd främjar SVA-elevers språkutveckling; (2) om SVA-elevernas modersmål och flerspråkighet beaktas och ses som resurs gynnar det eleverna; (3) lärare som har gott samarbete skapar lektioner som är i högre grad överensstämmande gällande innehåll och att de har mer kontakt om SVA-elevernas utveckling.

The objective of this master’s thesis was to describe current capabilities of anonymous browsing over the Internet. The theoretical part focuses on three main methods of anonymization with main focus on Tor network. The master‘s thesis describes advantages and disadvantages of different solutions and possible attacks on them. In the next part is demonstrated Tor network, implementation of Hidden service and secured access to the server for clients and possible attacks against this proposal. The work also includes the results of measurements of all three anonymizers and the effects on their speed.

Abstrakt Syftet med studien är att undersöka herrelitföreningarnas beroende av yttre partners. Samtidigt lyfta fram elitföreningarnas användning av kommersiell verksamhet och hur det påverkar deras ekonomi. Studien kommer också att diskutera fördelar och nackdelar som de undersökta föreningarna ser med införandet av idrottsaktiebolag, eftersom idrottsföreningens går mot ett mer företagsliknande förhållningssätt. Studien är förankrad i den osäkra miljön som bildas när kommersialisering och det ideella idealet ställs mot varandra inom svensk idrott. Forskning instämmer i att idrotten måste skapa en balans mellan kommersialisering och ideell idealet. Å andra sidan råder en viss oenighet om kommersiella intäkter handlar om vinstmaximering eller nyttomaximering. Resource Dependence Theory används för att förklara hur partners minskar deras beroende och osäkerheter i miljön de arbetar i förhållande till yttre partners. Metoden som används är en blandning av kvantitativ och kvalitativ forskning, genom ett frågeformulär som innehåller frågor i en blandning av enkätfrågor och semistrukturerade intervjufrågor. Sexton respondenter deltog i studien. Studien visar att herrelitföreningar tycker att samarbete med externa partners är något att sträva efter, men att det också skapar ett beroende av dessa externa partners. Det verkar också som om beroendet är oförändrat oavsett sammansättningsform. / Abstract The purpose of the study is to investigate the dependence of associations on external organizations. At the same time highlight the sports associations' use of commercial activities and how it affects their finances. The study will also discuss the advantages and disadvantages that the surveyed associations see with the incorporation of sports associations, as the sports associations world is moving towards a more corporate-like approach. The study is rooted in the uncertain environment that is formed when commercialization and the non-profit ideal are set against each other within Swedish sports. Research agrees that sport needs to strike a balance between commercialization and the non-profit ideal. On the other hand, there is disagreement as to whether commercial revenue is about profit maximization or utility maximization. Resource Dependence Theory is used to explain how organizations reduce their dependence and uncertainties in the environment they operate in relation to external partners. The method applied is a mixture of quantitative and qualitative research, through a questionnaire containing questions in a mixture of survey and semi-structured interview questions. Sixteen respondents participated in the study. The study shows that elite sports associations find that collaboration with external organizations is something to strive for, but that it also creates a dependency on these external organizations. It also appears that the dependency is unchanged regardless of the form of association.

Stena Recycling is one of the leading recycling companies in Sweden and at their facility in Halmstad, 300 tonnes of refuse are handled every day where aluminium is one of the most valuable materials they sort. Today, most of the sorting process is done automatically, but there are still parts of the refuse that are not correctly sorted. Approximately 4\% of the aluminium is currently not properly sorted and goes to waste. Earlier works have investigated using machine vision to help in the sorting process at Stena Recycling. However, consistently through all these previous works, there is a problem in gathering enough annotated data to train the machine learning models. This thesis aims to investigate how machine vision could be used in the recycling process and if pre-training models using self-supervised learning can alleviate the problem of gathering annotated data and yield an improvement. The results show that machine vision models could viably be used in an information system to assist operators. This thesis also shows that pre-training models with self-supervised learning may yield a small increase in performance. Furthermore, we show that models pre-trained using self-supervised learning also appear to transfer the knowledge learned from images created in a lab environment to images taken at the recycling plant.

Dokumentet är ett resultat av studier gjorda under kursen Kandidatarbete I Datavetenskap. Arbetet utforskade, genom fallstudie, två egenskaper av distribuerade informationssystem och relation mellan dessa: säkerhet och prestanda. Målet med fallstudien har varit att belysa nackdelen med användning av Secure Socker Layer (SSL) dvs. dess effekt på hastigheten och fördelen med SSL, dvs. SSL:s roll i informationssäkerhetsarbetet. Arbetet visar hur prestanda i ett tillämpad distribuerat informationssystem kan påverkas av en SSL tillämpning. Systemets responstid testades för skillnader mellan en SSL säkrad uppkoppling och utan. Det testade systemet var ett bokningssystem som används för administration av resor, utvecklat i DotNet utvecklingsplattform. Arbetet har dessutom visat genom studien av informationssäkerhetsstandarden ledningssystem för informationssäkerhet (LIS) vilken plats som SSL protokollet har i informationssäkerhetsarbetet i organisationer. Metoden för jämförelse utvecklades och baserades på interaktionsmodellen. Hypotesen för arbetet var att mjukvara som tillämpar SSL gör att responstiden blir längre men gör också att informationssystemet uppfyller krav enligt standarden för ledningssystem av informationssäkerhet SS-ISO/IEC 17799 och SS 62 77 99-2. Hypotesen bekräftades då resultatet för mätningen visade en ökning på 37,5 % i medel för klienten med säkrad SSL uppkoppling och att resultatet av LIS studien visade att organisationer uppfyller viktiga krav ställda i standarden genom at ha en SSL säkrad kommunikation i sitt informationssystem. / This study shows the impact of SSL application on performance in a distributed information system. Further, the case study shows also, through studies of information security standard SS-ISO/IEC 17799, the place that SSL has in applying information security in organisations. / dejanpetrusic@hotmail.com, is00dpe@student.bth.se

The Master’s Thesis deals with the design and implementation of a web application for testing the security of SSL/TLS protocols on a remote server. The web application is developed in the Nette framework. The theoretical part describes SSL/TLS protocols, vulnerabilities, recommendations and technologies used in the practical part. The practical part is devoted to the creation of a web application with the process of using automatic scripts to test and display the results on the website with a rating of A+~to~C. The web application also displays a list of detected vulnerabilities and their recommendations.

The aim of this thesis is to study and describe the theme of Public Key Infrastructure (PKI). Within the scope of minute PKI characterization there is a gradual depiction of particular structural elements, which are above all represented by cryptographic operations (asymetric and symetric cryptography, hash function and digital signature); then, there are also individual PKI subjects that are dealt with, like eg. certification authority, certificates, security protocols, secure heap etc. Last but not least there are a few complete Public Key Infrastructure implementation solutions described (OpenSSL, Microsft CA). The practical part of the thesis, a lab exercise, gives potential students the knowledge of installing OpenSSL system based certification authority. The next task educate students how to secure web server with certificate signed with own CA and also how to secure web server users‘ access control through certificates signed by the previously installed CA.

Master’s thesis analyzes in detail the security of electronic banking within the chosen banks in Czech republic. On the base of these knowledge it defines and recommendes the most secure electronic banking for Profes Project s.r.o. company. In the folowing it investigates a current electronic banking in the company and it carries out basic theoretical findings.