Information Leakage Measurement and Prevention in Anonymous Traffic

University of Minnesota Ph.D. dissertation. June 2019. Major: Computer Science. Advisor: Nick Hopper. 1 computer file (PDF); viii, 76 pages.The pervasive Internet surveillance and the wide-deployment of Internet censors lead to the need for making traffic anonymous. However, recent studies demonstrate the information leakage in anonymous traffic that can be used to de-anonymize Internet users. This thesis focuses on how to measure and prevent such information leakage in anonymous traffic. Choosing Tor anonymous networks as the target, the first part of this thesis conducts the first large-scale information leakage measurement in anonymous traffic and discovers that the popular practice of validating WF defenses by accuracy alone is flawed. We make this measurement possible by designing and implementing our website fingerprint density estimation (WeFDE) framework. The second part of this thesis focuses on preventing such information leakage. Specifically, we design two anti-censorship systems which are able to survive traffic analysis and provide unblocked online video watching and social networking

A Bayesian approach to Hybrid Choice models

Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2010-2011Les modèles microéconométriques de choix discrets ont pour but d’expliquer le processus du choix individuel des consommateurs parmi un ensemble limité et exhaustive d’options mutuellement exclusives. Les modèles dits de choix hybrides sont une généralisation des modèles de choix discrets standard, où des modèles indépendants plus sophistiqués sont considérés simultanément. Dans cette thèse des techniques d’estimation simultanée sont analysées et appliquées pour un modèle de choix hybride qui, sous la forme d’un système complexe d’équations structurelles généralisées, intègre à la fois des choix discrets et des variables latentes en tant que facteurs explicatifs des processus décisionnels. Ce qui motive l’étude de ce genre de modèles est que pour comprendre le processus du choix il faut incorporer des attitudes, des perceptions et des attributs qualitatifs à l’intérieur de modèles décisionnels économiques conventionnels, tout en prenant ce qui dit la recherche en sciences cognitives ainsi qu’en psychologie sociale. Quoique l’estimation du système d’équations d’un modèle de choix hybride requière l’évaluation d’intégrales multidimensionnelles complexes, on résoudre empiriquement ce problème en applicant la méthode du maximum de vraisemblance simulée. Ensuite on dérive une procédure d’échantillonnage de Gibbs pour l’estimation simultanée bayésienne du modèle qui offre des estimateurs convergents et efficaces. Ceci devient une méthode plus avantageuse comparativement aux méthodes classiques dans un cadre analytique avec un grand nombre de variables latentes. En effet, en vertu de l’approche bayésienne il suffit de considérer des régressions ordinaires pour les variables latentes. Par ailleurs, dériver les intervalles de confiance bayésiennes pour les parts de marché ainsi que pour des dispositions à payer devient trivial. De par sa grande géneralité, le modèle de choix hybride est capable de s’adapter à des situations pratiques. En particulier, la réponse des consommateurs suite à l’innovation technologique est analysée. Par exemple, on étudie les préférences pro-environnementales dans un modèle économique des décisions d’achat de véhicules verts selon lequel les consommateurs soucieux de l’environnement sont prêts à payer davantage pour des véhicules à faibles émissions, en dépit des inconvénients potentiels. En outre, en utilisant un noyau probit et des indicateurs dichotomiques on montre que des connaissances préalables ainsi que des attitudes positives envers l’adoption de nouvelles technologies favorisent l’adoption de la téléphonie IP.Microeconometric discrete choice models aim to explain the process of individual choice by consumers among a mutually exclusive, exhaustive and finite group of alternatives. Hybrid choice models are a generalization of standard discrete choice models where independent expanded models are considered simultaneously. In my dissertation I analyze, implement, and apply simultaneous estimation techniques for a hybrid choice model that, in the form of a complex generalized structural equation model, simultaneously integrates discrete choice and latent explanatory variables, such as attitudes and qualitative attributes. The motivation behind hybrid choice models is that the key to understanding choice comes through incorporating attitudinal and perceptual data to conventional economic models of decision making, taking elements from cognitive science and social psychology. The Bayesian Gibbs sampler I derive for simultaneous estimation of hybrid choice models offers a consistent and efficient estimator that outperforms frequentist full information simulated maximum likelihood. Whereas the frequentist estimator becomes fairly complex in situations with a large choice set of interdependent alternatives with a large number of latent variables, the inclusion of latent variables in the Bayesian approach translates into adding independent ordinary regressions. I also find that when using the Bayesian estimates it is easier to consider behavioral uncertainty; in fact, I show that forecasting and deriving confidence intervals for willingness to pay measures is straightforward. Finally, I confirm the capacity of hybrid choice modeling to adapt to practical situations. In particular, I analyze consumer response to innovation. For instance, I incorporate proenvironmental preferences toward low-emission vehicles into an economic model of purchase behavior where environmentally-conscious consumers are willing to pay more for sustainable solutions despite potential drawbacks. In addition, using a probit kernel and dichotomous effect indicators I show that knowledge as well as a positive attitude toward the adoption of new technologies favor the adoption of IP telephony

A Comprehensive Survey of Voice over IP Security Research

We present a comprehensive survey of Voice over IP security academic research, using a set of 245 publications forming a closed cross-citation set. We classify these papers according to an extended version of the VoIP Security Alliance (VoIPSA) Threat Taxonomy. Our goal is to provide a roadmap for researchers seeking to understand existing capabilities and to identify gaps in addressing the numerous threats and vulnerabilities present in VoIP systems. We discuss the implications of our findings with respect to vulnerabilities reported in a variety of VoIP products. We identify two specific problem areas (denial of service, and service abuse) as requiring significant more attention from the research community. We also find that the overwhelming majority of the surveyed work takes a black box view of VoIP systems that avoids examining their internal structure and implementation. Such an approach may miss the mark in terms of addressing the main sources of vulnerabilities, i.e., implementation bugs and misconfigurations. Finally, we argue for further work on understanding cross-protocol and cross-mechanism vulnerabilities (emergent properties), which are the byproduct of a highly complex system-of-systems and an indication of the issues in future large-scale systems

Lab experiences for teaching undergraduate dynamics

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (p. 443-466).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.This thesis describes several projects developed to teach undergraduate dynamics and controls. The materials were developed primarily for the class 2.003 Modeling Dynamics and Control I. These include (1) a set of ActivLab modular experiments that illustrate the dynamics of linear time-invariant (LTI) systems and (2) a two wheeled mobile inverted pendulum. The ActivLab equipment has been designed as shareware, and plans for it are available on the web. The inverted pendulum robot developed here is largely inspired by the iBOT and Segway transportation devices invented by Dean Kamen.by Katherine A. Lilienkamp.S.M

Time Delay Compensation Schemes with Application to Networked Control System

In the project an extensive study of network parameters like data packet drops, data packet delays are pursued by using a network simulator (NS-2). It simulates the transmission of sensor and control packets between plants and controllers. Some fundamental examples were done using this network simulator. Time delay occurs used for networked control system when the exchange of data among sensors, actuators and controllers connected through the shared medium. Such delays affect the system Performance degradation and the reduced stability or total instability of the closed-loop system. In order to compensate time-delay in the networked control system (NCS) there are different time delay compensation schemes are available, which is given by predictive controller, PID controller, LQR controller, fuzzy controller, etc. In this thesis the discrete-time PID controller is used for compensating the time delays in the networked control system. To study in reality an experimental work is done to transfer packet data between two computer systems through a Local area Network (LAN) using UDP protocol. Subsequently the transfer of signal between two computer systems through a LAN using UDP protocol has been also made. These experiments were carried out using SIMULINK Instrument Control Toolbox (ver7.6). Networked predictive control is also designed for networked control of servo system. This control strategy is applied to a servo control system through the Local Area Network (LAN).SMITH-PREDICTOR proposed to compensate the communication delays in the networked control system

Antitrust as Regulation

Antitrust, properly understood, plays a modest role in constraining commercial behavior. With respect to unilateral conduct, it does not prohibit monopoly or the fortuitous or quality-based acquisition of the same. It generally permits dominant companies to enjoy the fruits of their positions and does not speak to the propriety of excessive pricing. It does not impose service obligations on monopolists, nor does it generally limit their right to price discriminate amongst their consumers. It merely prohibits monopolists\u27 artificial creation of impediments to competition--so-called exclusionary practices. With respect to concerted behavior, the law allows a vast swathe of private agreements, even between rivals and if restrictive of competition, so long as the arrangement sufficiently promotes the well-being of consumers. These tenets of competition policy reflect a sound maxim: antitrust is not regulation. Unfortunately, the judiciary has lost sight of this rudimentary principle. The erosion began subtly, as lower courts rewrote antitrust law\u27s principal mode of analysis, the rule of reason. According to the Supreme Court\u27s seminal pronouncement of the rule, if economic analysis reveals that a practice enhances an appropriate measure of consumer welfare, the practice is lawful. That analytic inquiry does not insist that companies calibrate their behavior to maximize efficiency. The U.S. Courts of Appeals, however, have rewritten the rule of reason to require more. Today, an antitrust defendant cannot necessarily prevail by showing that its challenged restraint is welfare enhancing. Instead, if a court finds that a defendant could have achieved comparable efficiency gains in a manner less prejudicial to competition, a violation of the Sherman Act will follow. Although recent calls for antitrust to require the best have intuitive appeal, policymakers should reject them in most cases. Where welfare analysis requires one to appeal to a hypothetical counterfactual-as is typically the case, courts invariably operate in an error-prone manner. Here, antitrust should play a role founded on incremental improvement over the status quo. Any other function would blur the lines between antitrust and regulation, thus subjecting the courts and agencies to tasks for which they are ill-suited. Recent enforcement actions and judicial proceedings reveal the dangers of requiring welfare maximization, as antitrust now threatens to undo desirable gains in a self-defeating pursuit for more

Cabining Intellectual Property through a Property Paradigm

One of the most revolutionary legal changes in the past generation has been the “propertization” of intellectual property (IP). The duration and scope of rights expand without limit, and courts and companies treat IP as absolute property, bereft of any restraints. But astonishingly, scholars have not yet recognized that propertization also can lead to the narrowing of IP. In contrast to much of the literature, which criticizes the propertization of IP, this Article takes it as a given. For the transformation is irreversible, sinking its tentacles further into public and corporate consciousness (as well as the IP laws) with each passing day and precluding the likelihood that IP will return to the prepropertization era. This Article therefore ventures onto a new path, one that follows property into unexpected briar patches of limits. The secret here is that property is not as absolute as it is often claimed to be. After surveying fifty doctrines in property law, Professor Carrier synthesizes limits based on development, necessity, and equity. He then utilizes these limits to construct a new paradigm for IP. The paradigm facilitates the reorganization of defenses that courts currently recognize as well as a more robust set of defenses, which include (1) a new tripartite fair use doctrine in copyright law, (2) a new defense for public health emergencies and a recovered experimental use defense and reverse doctrine of equivalents in patent law, (3) a development-based limit to trademark dilution, and (4) a functional use defense for the right of publicity. By adopting the paradigm of property, IP has reopened the door to limits. Rediscovering these limits offers significant promise for the future of innovation and democracy

Investigation of an intelligent personalised service recommendation system in an IMS based cellular mobile network

Success or failure of future information and communication services in general and mobile communications in particular is greatly dependent on the level of personalisations they can offer. While the provision of anytime, anywhere, anyhow services has been the focus of wireless telecommunications in recent years, personalisation however has gained more and more attention as the unique selling point of mobile devices. Smart phones should be intelligent enough to match user’s unique needs and preferences to provide a truly personalised service tailored for the individual user. In the first part of this thesis, the importance and role of personalisation in future mobile networks is studied. This is followed, by an agent based futuristic user scenario that addresses the provision of rich data services independent of location. Scenario analysis identifies the requirements and challenges to be solved for the realisation of a personalised service. An architecture based on IP Multimedia Subsystem is proposed for mobility and to provide service continuity whilst roaming between two different access standards. Another aspect of personalisation, which is user preference modelling, is investigated in the context of service selection in a multi 3rd party service provider environment. A model is proposed for the automatic acquisition of user preferences to assist in service selection decision-making. User preferences are modelled based on a two-level Bayesian Metanetwork. Personal agents incorporating the proposed model provide answers to preference related queries such as cost, QoS and service provider reputation. This allows users to have their preferences considered automatically

Developing a traffic control device maintenance management system interfacing with Gis

Roadway systems contain a wide variety of spatially distributed physical features which require installation, maintenance and replacement. These features include traffic control devices such as signs, signals, pavement markings and streetlights. Several technologies exist that can be utilized by the transportation sector to improve program management of a number of these features. Geographic Information Systems (GIS) technology provides a powerful environment for the capture, storage, retrieval, analysis, and display of spatial (locationally defined) data. A need exists to provide an inventory of the transportation physical plant to interface with a work management system. Information pertaining to the number and condition of such features is required for planning, operating, maintaining, managing and budgeting needs. This thesis summarizes the development of a user-friendly, computerized process to establish a graphical interface between a roadway inventory database and GIS; Evaluation of existing technologies and a survey of current literature will provide a basis for the design of a Traffic Control Device Maintenance Management System. This system will provide a consistent form of technology transfer on a common platform. This system will manage resources by integrating work-orders and the database. The system will utilize GIS technology to integrate a work-order system and a database reporting system for resource management. The work order interface capabilities will include maintenance work-order management, project cost and progress tracking, and program planning and policy analysis; The key is to develop a user-friendly system useful to both the field-level installation crews and planning-level management. A case study in Clark County, Nevada, will be used to evaluate alternative methods of collecting and data on traffic control devices and to illustrate the development of a GIS-based management system. This system is intended to improve the efficiency and effectiveness of operational practices as well as serve as a vital decision support tool for planning and management