Several types of discrepancies have been examined between CFD simulations, wind tunnel measurements and real world conditions. The results of different wheel rotation methods show that while stationary approaches can often substitute real unsteady wheel rotation, they can also be very sensitive to the exact angular positioning of wheel rims. Using both measured and computed flow fields, the lower part of wheel wake was identified as a key area, showing differences between rotation methods and sources of simulation errors in general. It was also shown that the level of detail in tyre geometry and its deformation near contact patch do not have a large impact on accuracy. Due to the absence of tyre rotation, the tyre sidewall was identified as an important place of flow separation with large effect on flow field and forces. Angle of attack study confirmed that assessing purely straight-line drag causes its under prediction compared to real-world values. This judgement would however benefit from obtaining data in more adverse conditions compared to those currently available. Finally, tyre radial expansion was investigated, causing a drop in drag with increasing vehicle velocity and altering the flow around the rear bodywork. Ignoring this effect can therefore negatively influence the aerodynamic development of a vehicle.

The PRINCE algorithm is a faster and more advanced version of a combination attack. Non-distributed password breaking often encounters its limits, and its applicability to real tasks decreases due to the increasing demand for computing resources of the device. The aim of this work is to design a distributed version of the the PRINCE attack as an extension of Fitcrack system, which focuses on distributed password cracking. The proposed design is implemented and integrated into the Fitcrack system. The work examines the PRINCE attack on a set of experiments, which examines the impact of various configuration options. Part of the experimental part is a comparison of the PRINCE attack with the dictionary and combination attack. The purpose of the comparison is to find cases where the PRINCE attack is better than other attacks. Finally, the integrated PRINCE attack solution in the Fitcrack system is compared with the solution implemented in the Hashtopolis system.

This text deals with computer network security using honeypot technology, as a tool of intentional trap for attackers. It closely describes basic thoughts, together with advantages and disadvantages of this concept. The main aim is a low interaction honeypot Honeyd, its functionality and possible extensional features. As a practical part of the text there is a description of principles of implementation Honeyd service scripts, which are represented as a simulation of behavior of computer worm Conficker. Further it describes creation of automated script used for analysis and processing of gathered data, captured during actual deployment of Honeyd in Internet network.

This thesis describes design and implementation of application for offline NetFlow data annotation from perspective of network security. In this thesis is explained the NetFlow architecture in detail along with methods for security incidents detection in the captured data. The application design is based on analysis of manual annotation and supported by several UML diagrams. The Nemea system is used for detecting security events and Warden system as a source of information about reported security incidents on the network. The application uses technologies such as PHP 5, Nette framework, jQuery library and Bootstrap framework. The CESNET association provided NetFlow data for testing the application. The result of this thesis could be used for analysis and annotation of NetFlow data. Resulting data set could be used to verify proper functionality of detection tools.

This thesis describes principles of specific HTTPS attacks and provides realization of attacks using lab environment based on VMware. Elaboration is divided to specific dedicated attacks, each part evaluates risk of vulnerability and describes the way of realization in guides for students and lector´s manuals.

La biométrie suscite de plus en plus d’intérêt de la part des industriels car nous avons besoin de nouvelles méthodes d’authentification d’un individu : pour du contrôle d’accès physique, du contrôle aux frontières ou pour du paiement. Ces données non révocables et sensibles sont très souvent stockées sur des systèmes embarqués de type élément sécurisé (SE), comme par exemple une carte à puce. Ces SE embarquent aussi un module de comparaison nommé On-Card-Comparison (OCC), permettant de déterminer si le template présenté correspond bien à celui stocké sur l’élément sécurisé. Dans cette thèse, nous nous intéressons particulièrement aux empreintes digitales car c’est une modalité biométrique bien perçue par les usagers. Nous proposons dans cette thèse différentes contributions permettant d’évaluer des systèmes biométriques embarqués. La première est une plateforme d’évaluation de systèmes biométriques nommée EVABIO. La seconde contribution, permet d’évaluer l’incidence sur les performances lors de la réduction de templates biométriques lorsqu’ils doivent être stockés sur un SE. Nous proposons des méthodes permettant de réduire la taille du template biométrique tout en gardant un taux de reconnaissance élevé, garantissant ainsi un bon niveau de performance du système biométrique complet. La dernière contribution étudie les attaques d’un système biométrique embarqué sur SE. Nous regardons quels a priori sont importants pour un imposteur : nous avons montré que le type de l’empreinte digitale est une information importante pour un attaquant. Nous avons également proposé une contre-mesure pour les systèmes embarqués. / Biometrics is sparking the interest of manufacturers and industrial compagniesbecause we are in need of new methods of authenticating individuals: for physicalaccess control, border control or for payments. Non-revocable and sensitive data isvery often stored on embedded systems of the secure element type (SE), such as asmart card. SEs include a comparison module called On-Card-Comparison (OCC),which determines whether the template presented corresponds to the template storedwithin it. In this thesis, we are particularly interested in fingerprints because it is abiometric modality that is very well perceived by the population.We propose in this thesis different contributions to evaluate embedded biometricsystems. The first is a biometric evaluation platform called EVABIO. The secondcontribution evaluates the impact on performance when reducing biometric templatesthat are to be stored on an SE. We propose methods to reduce the size of biometrictemplates while maintaining a high recognition rate thus, guaranteeing a good level ofperformance of the global biometric system. The last contribution studies attacks ona biometric system that is embedded on a SE. We look at what a priori are importantfor an impostor: we have shown that the type of fingerprint is an important a prioriand the reason why we have also proposed a countermeasure for embedded systems.

In recent years, the advent of Long Term Evolution (LTE) technology as a prominent component of 4G networks and future 5G networks, has paved the way for fast and new mobile web access and application services. With these advantages come some security concerns in terms of attacks that can be launched on such networks. This thesis focuses on the impact of the mobile botnet on LTE networks by implementing a mobile botnet architecture that initiates a Distributed Denial of Service (DDoS) attack. First, in the quest of understanding the mobile botnet behavior, a correlation between the mobile botnet impact and different mobile device mobility models, is established, leading to the study of the impact of the random patterns versus the uniform patterns of movements on the mobile botnet’s behavior under a DDoS attack. Second, the impact of two base transceiver station selection mechanisms on a mobile botnet behavior launching a DDoS attack on a LTE network is studied, the goal being to derive the effect of the attack severity of the mobile botnet. Third, an epidemic SMS-based cellular botnet that uses an epidemic command and control mechanism to initiate a short message services (SMS) phishing attack, is proposed and its threat impact is studied and simulated using three random graphs models. The simulation results obtained reveal that (1) in terms of users’ mobility patterns, the impact of the mobile botnet behavior under a DDoS attack on a victim web server is more pronounced when an asymmetric mobility model is considered compared to a symmetric mobility model; (2) in terms of base transceiver station selection mechanisms, the Distance-Based Model mechanism yields a higher threat impact on the victim server compared to the Signal Power Based Model mechanism; and (3) under the Erdos-and-Reyni Topology, the proposed epidemic SMS-based cellular botnet is shown to be resistant and resilient to random and selective cellular device failures. / Graduate

<div>In this thesis, we focus on the problem of estimating an unknown quantity of interest, when the information required to do so is dispersed over a network of agents. In particular, each agent in the network receives sequential observations generated by the unknown quantity, and the collective goal of the network is to eventually learn this quantity by means of appropriately crafted information diffusion rules. The abstraction described above can be used to model a variety of problems ranging from environmental monitoring of a dynamical process using autonomous robot teams, to statistical inference using a network of processors, to social learning in groups of individuals. The limited information content of each agent, coupled with dynamically changing networks, the possibility of adversarial attacks, and constraints imposed by the communication channels, introduce various unique challenges in addressing such problems. We contribute towards systematically resolving some of these challenges.</div><div><br></div><div>In the first part of this thesis, we focus on tracking the state of a dynamical process, and develop a distributed observer for the most general class of LTI systems, linear measurement models, and time-invariant graphs. To do so, we introduce the notion of a multi-sensor observable decomposition - a generalization of the Kalman observable canonical decomposition for a single sensor. We then consider a scenario where certain agents in the network are compromised based on the classical Byzantine adversary model. For this worst-case adversarial setting, we identify certain fundamental necessary conditions that are a blend of system- and network-theoretic requirements. We then develop an attack-resilient, provably-correct, fully distributed state estimation algorithm. Finally, by drawing connections to the concept of age-of-information for characterizing information freshness, we show how our framework can be extended to handle a broad class of time-varying graphs. Notably, in each of the cases above, our proposed algorithms guarantee exponential convergence at any desired convergence rate.</div><div><br></div><div>In the second part of the thesis, we turn our attention to the problem of distributed hypothesis testing/inference, where each agent receives a stream of stochastic signals generated by an unknown static state that belongs to a finite set of hypotheses. To enable each agent to uniquely identify the true state, we develop a novel distributed learning rule that employs a min-protocol for data-aggregation, as opposed to the large body of existing techniques that rely on "belief-averaging". We establish consistency of our rule under minimal requirements on the observation model and the network structure, and prove that it guarantees exponentially fast convergence to the truth with probability 1. Most importantly, we establish that the learning rate of our algorithm is network-independent, and a strict improvement over all existing approaches. We also develop a simple variant of our learning algorithm that can account for misbehaving agents. As the final contribution of this work, we develop communication-efficient rules for distributed hypothesis testing. Specifically, we draw on ideas from event-triggered control to reduce the number of communication rounds, and employ an adaptive quantization scheme that guarantees exponentially fast learning almost surely, even when just 1 bit is used to encode each hypothesis. </div>

John Warden är en inflytelserik luftmaktsteoretiker som låg bakom koalitionens luftkampanj mot Irak 1991. Han menar att luftmakt bör användas för att slå ut motståndarens motståndskraft genom att rikta anfall mot kritiska tyngdpunkter. Han illustrerar tyngdpunkterna genom att måla upp motståndaren som ett system bestående av fem ringar som visar hur systemet bör angripas. Shaun Clarke menar att småstater inte kan använda Wardens luftmaktsteori eftersom det kräver stor massa och därför en stormakts resurstillgångar. Han lanserar därför SPOT-paradigmet som en väg för småstaten att anamma strategisk bombning på ett resurseffektivt sätt. Denna studie prövar Wardens och Clarkes förklaringskraft genom en fallstudie på Israels luftmaktsutövande under operation Protective Edge 2014, för att se om Clarkes påstående är giltigt och om SPOT-paradigmet är användbart för småstaten.Studien visar att femringsmodellen har låg förklaringskraft på Israels nyttjande av luftmakt. Man har i huvudsak inte följt Wardens rekommendationer. SPOT-paradigmet har däremot hög förklaringskraft och studien förefaller stärka teorin i småstatens luftanfall mot en svagare motståndare.

I detta examensarbete görs en analys av säkerheten hos några av de driftundercentraler som används i fastigheter som Riksbyggen förvaltar. Driftundercentralerna används för att kontrollera olika delar i en fastighet, exempelvis belysning och temperatur. I de flesta fall nås respektive driftundercentral via en egen publik IP-adress, medan vissa tillverkare har en molntjänst för sina driftundercentraler. Syftet med examensarbetet har varit att undersöka de olika driftundercentralernas säkerhet, upptäcka brister och ge förbättringsförslag till dessa. Därutöver ges också exempel på hur smarta hem kan byggas upp. Undersökningen har gjorts på flera sätt, dels med hjälp av kontrollerade attacker men även genom att samla information om driftundercentralerna och hur de fungerar. Utifrån de undersökningar som gjorts har ett antal brister kunnat konstateras, bl.a. när det gäller lösenordens styrka och kryptering av dessa. Generella förslag på förbättringar har getts för att minska sårbarheten för eventuella attacker som kan ske i framtiden. / This project presents an analysis of the security regarding some of the controllers which are used in real estates managed by Riksbyggen. The controllers are used to control different parts of a property, such as lighting and temperature. In most cases, the controllers are reached via their own public IP address, while some manufacturers have a cloud service for their controllers. The purpose with this project has been to examine the different controllers’ security, discover weaknesses and provide suggestions for improvements to these. In addition, examples are also given on how smart homes can be built. The study has been made in several ways, partly with the help of controlled attacks but also by gathering information about the controllers and how they operate. Based on the studies that were made, a number of weaknesses have been observed, including passwords’ strength and encryption of these. General suggestions for improvements have been given to reduce the vulnerability for possible attacks that may occur in the future.