With current state-of-the-art privacy-preserving blockchain solutions, users can submit transactions to a blockchain while maintaining full anonymity and not leaking the contents of the transaction through cryptographic techniques like zero-knowledge proofs and homomorphic encryption. However, the architecture of a blockchain consists of a decentralized network where every network participant maintains their own local copy of the blockchain and updates it upon every added transaction. As a result, the volume of blockchain transactions and the timestamp of each blockchain transaction for an application is publicly available. This is problematic for applications with time-sensitive or volume-sensitive outcomes because users may want this information to be privatized, such as not leaking the lateness of student examinations. However, this is not possible with existing blockchain research. In this thesis, we propose a blockchain system for multi-party applications that does not leak any useful information from the volume and timing metadata of the application's transactions, including maintaining the privacy of a time-sensitive or volume-sensitive outcome. We achieve this by adding sufficient noise using indistinguishable decoy transactions such that an adversary cannot deduce which transactions actually impacted the outcome of the application. This is facilitated in a manner where anyone can publicly verify the application's execution to be correct, fair, and honest. We demonstrate and evaluate our approach by implementing a Dutch auction that supports decoy bid transactions on a private Ethereum blockchain network. / Master of Science / Blockchains are distributed, append-only, digital ledgers whose current state is continuously agreed upon through the consensus of network participants and not by any centralized party. These characteristics make them unique for many applications because they enable the application to be facilitated and executed in a public, verifiable, decentralized, and tamper-proof manner. For example, Bitcoin, the most popular cryptocurrency, uses blockchains to continuously maintain a permanent, verifiable ledger of payment transactions. However, one downside of this public architecture is that the volume of transactions and the timestamp of each transaction can always be publicly observed (e.g. the timestamp of every Bitcoin payment is public). This is problematic for applications with time-sensitive or volume-sensitive outcomes because users may want this volume and timing information to be privatized, such as not leaking the lateness of student examinations which could have severe consequences like violating student privacy laws. But currently with state-of-the-art blockchain research, privatizing this information is not possible. In this thesis, we demonstrate our approach that enables these time-sensitive and volume-sensitive applications to be implemented on blockchains in a manner that can maintain the privacy of these time-sensitive or volume-sensitive outcomes without sacrificing the application's integrity or verifiability. We then demonstrate and evaluate our approach through implementing a Dutch auction that supports decoy bid transactions on a private blockchain network.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / In our first installment, analog and HD video terms were compared. It was shown that resolution is three-dimensional in HD. High HD data rates force the use of video compression in order to transport video. Compression compromises video detail and introduces latency. Latency affects the overlay of time critical measurements. It is therefore important to time stamp at the source. In this volume, the focus is on the key regions of the HD video frame and metadata. SMPTE specifications are the foundation on which MISB builds its use of metadata. It will be shown that only two KLV packets can hold all TSPI and calibration data with frame-by-frame updates. This capacity is new in HD. Metadata is permanently merged with images and the time that both were collected. We show how employing the KLV metadata packet can result in a single video record where picture taking are all in lockstep. Using KLV metadata enables one to record clean video while retaining the ability to place crosshairs and data during playback.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / In the past several years there has been a good amount of effort expended in migrating telemetry streams to IP-based infrastructure, especially in the area of ground-based transport. This has yielded a number of benefits, from leveraging the properties of IP transport to enable multicast transport, to the integration of the wide number of COTS equipment that also is IP-based, such as digital video encoder/decoders into range networks. This paper will provide a model for identifying areas to accelerate the integration of IP-based assets into the range infrastructure at the application level. In particular the integration of metadata between the telemetry and video application interfaces will be explored.

Samtidighetskonflikt, även känt under den engelska termen concurrency conflict, uppstår när två eller flera processer försöker uppdatera samma information i en databas vid samma tidpunkt. Processen som sparar ändringarna sist blir de ändringar som gäller och på så sätt kan viktigt information försvinna. Det finns flera tillvägagångssätt för att förhindra dessa problem med olika typer av samtidighetskontroller som kan ske i applikationen eller redan på databasnivå via lagrade procedurer. Metoden som används för att undersöka problemområdet har utgått från ett praktiskt arbete med en utökning av en existerande applikation, webbutiken RoyalDesign, skriven i ASP.NET (ASP-dotnet) Web Forms. Utökningen kräver samtidighetskontroll där användaren ska informeras av eventuella konflikter. Undersökningen avser att granska hur samtidighetskontroll implementeras och hanteras i applikationen. Resultatet av undersökningen visar databasen gör den största delen av arbetet, fångar samtidighetskonflikter samt kastar ett undantag som sedan applikationen fångar och hanterar.

In general, the Internet represents an unsecured medium of data transfer. Besides the rising popularity of the Internet, the matters of safety are getting to the foreground of importance. Anybody would be able to gain access to the computer network or to other valuable information if no algorithm of verifying the genuineness of identity were used. It is necessary to secure not only the access to the documents but also the content itself, which could be modified during the transfer through an unsecured medium. Last but not least, without the discretion provided by cryptography, the information may become literally public. To provide security and protection for the communicating participants the problems mentioned above are solved with the help of cryptographic techniques. The verification of the identity and the integrity of messages, the credibility of document’s ownership and safe data transfer through an unsecured medium are all the aspects, which the field of communication security on the Internet, thus the public key infrastructure, deals with. The electronic signature, as a part of the security area, is one of many advertised themes nowadays in Czech Republic. The aim of this master’s thesis is to acquaint the reader with the necessary technological procedures of digital signature, such as cryptographic techniques, public key infrastructure and timestamp. The practical part of this thesis consists of a suggested implementation of a web application in the programming language ASP.NET, which forms a certification authority with an opportunity of claiming a timestamp to authorize timestamps. After the problematic of cryptography was explained in the first chapter, the term of electronic signature has been introduced in the second chapter. Very important information, as far as the electronic signature of documents is concerned, is the time of the document’s creation and the subsequent signature verification by an appropriate authority. So the following part of the thesis is dedicated to the timestamp and to the authority of its verification. The fourth section deals with the large scale of public key infrastructure. The fifth part focuses on the description of the support for the whole problem mentioned so far using Microsoft’s programming language ASP.NET. The final sixth chapter represents the practical part of the thesis, namely the web application itself, where the individual modules of the application with its functions are described.

Efficiently and accurately estimating bandwidths in packet networks is a problem that has intrigued researchers for years. There is no simple manner for estimating bandwidths in IPv4 networks that is accurate, efficient, flexible, and suitable for a variety of applications. Many of the available estimation techniques suffer from inherent flaws such as inaccuracy due to simple assumptions about the network or an overall high complexity that makes it inappropriate in all but a few highly specific situations. The next generation Internet Protocol, IP version 6, has the functionality necessary to implement feedback mechanisms to assist in accurate bandwidth estimations. This thesis proposes a timestamp hop-by-hop option for IPv6 and then applies this option to create a new bandwidth estimation technique. Instead of passive observations, the network infrastructure actively assists in bandwidth measurements resulting in a bandwidth estimation technique that is accurate, efficient, flexible, and suitable for many different applications and scenarios. Both analytical and simulation analysis show that the IPv6 bandwidth estimation technique outperforms a comparable IPv4 estimation method.

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-08-21T12:14:23Z No. of bitstreams: 1 Falkner de Arêa Leão Moraes.pdf: 2601896 bytes, checksum: 0fa8b49e3f279d911a70b4f78d9cbe08 (MD5) / Made available in DSpace on 2017-08-21T12:14:23Z (GMT). No. of bitstreams: 1 Falkner de Arêa Leão Moraes.pdf: 2601896 bytes, checksum: 0fa8b49e3f279d911a70b4f78d9cbe08 (MD5) Previous issue date: 2009-02-16 / Lack of security is a constant concern in open distributed systems. Threats are present within environments insecure, uncertain and constantly changing. Due to this problem, many tools for evaluating vulnerabilities of the network as well as for their protection are being developed as techniques for encryption and software systems such as antivirus, firewall and IDS (Intrusion Detection System). Among these, there are IDS systems that are being conceived, designed and implemented, using techniques executed by agents. However, it is necessary to assure security and reliability of exchanged messages inside IDS. For this purpose, this paper proposes a security solution for IDS based on agents. The proposed solution provides a methodology and a secure mechanism for communication among agents, through information protection configuration mechanisms, authentication and authorization, key control and messages persistence using XML. The proposed solution is implemented as an extension to the IDS-NIDIA (Network Intrusion Detection System based on Intelligent Agents), whose architecture has an intelligent agent society that communicate in a cooperative way in a distributed environment. The implementation of the prototype and tests proposed in this work show the applicability of the proposed solution. / A falta de segurança é uma preocupação constante em sistemas distribuídos abertos. Ameaças estão presentes dentro de ambientes inseguros, incertos e que mudam constantemente. Devido a esses problemas, diversas ferramentas para avaliação de vulnerabilidades da rede, bem como para sua proteção, estão sendo desenvolvidas como técnicas de criptografia e softwares como antivírus, firewall e IDS (Intrusion Detection System). Dentre estas, destaca-se Sistemas IDS que estão crescentemente sendo concebidos, projetados e implementados, usando técnicas de segurança executadas por agentes. Entretanto, é necessário que a segurança e a confiabilidade das mensagens trocadas dentro de um sistema IDS sejam asseguradas. Para este fim, este trabalho propõe uma solução segura e confiável para IDS baseada em agentes. A solução propõe estabelecer um esquema de execução e comunicação segura dos agentes através de mecanismos de proteção de informações de configuração, autenticação e autorização, controle de chaves e persistência de mensagens do IDS, utilizando XML. A solução proposta é implementada como uma extensão do IDS-NIDIA (Network Intrusion Detection System based on Intelligent Agents), cuja arquitetura consiste em uma sociedade de agentes inteligentes que se comunicam de forma cooperativa em um ambiente distribuído. A implementação do protótipo e os testes apresentados neste trabalho demonstram a aplicabilidade da solução proposta.

Basic way how to identify a device in computer network is by MAC address and IP address. Main goal of this work is to create an application capable of clear identification of devices in computer network regardless change of their MAC address or IP address. This is done by exploiting tiny deviations in hardware clock known as clock skew. They appear in every clock based on quartz oscillator. Using clock skew is beneficial, because there is no need of any changes in fingerprinted device nor their cooperation. Accessing these values is done by capturing packets with timestamps included. Application of this method is very wide, for example computer forensics, tracking the device using different access points or counting devices behind router with NAT.

Due to the complex diversity of contemporary Internet-services, computer network measurements have gained considerable interest during recent years. Since they supply network research, development and operations with data important for network traffic modelling, performance and trend analysis, etc. The quality of these measurements affect the results of these activities and thus the perception of the network and its services. This thesis contains a systematic investigation of computer network measurements and a comprehensive overview of factors influencing the quality of performance parameters obtained from computer network measurements. This is done using a novel network performance framework consisting of four modules: Generation, Measurement, Analysis and Visualization. These modules cover all major aspects controlling the quality of computer network measurements and thus the validity of all kinds of conclusions based on them. One major source of error is the timestamp accuracy obtained from measurement hardware and software. Therefore, a method is presented that estimates the timestamp accuracy obtained from measurement hardware and software. The method has been used to evaluate the timestamp accuracy of some commonly used hardware (Agilent J6800/J6830A and Endace DAG 3.5E) and software (Packet Capture Library). Furthermore, the influence of analysis on the quality of performance parameters is discussed. An example demonstrates how the quality of a performance metric (bitrate) is affected by different measurement tools and analysis methods. The thesis also contains performance evaluations of traffic generators, how accurately application-level measurements describe network behaviour, and of the quality of performance parameters obtained from PING and J-OWAMP. The major conclusion is that measurement systems and tools must be calibrated, verified and validated for the task of interest before using them for computer network measurements. A guideline is presented on how to obtain performance parameters at a desired quality level. / Datornät används i mer och mer i vårt dagliga liv, de används för att telefonera, läsa tidningar, se på TV, handla, boka resor etc. På grund av denna diversiteten bland tjänsterna så har mätningar blivit populära under senare år. Detta då de förser nätverksforskningen, utvecklingen och driften med data som används för trafik modellering, prestanda och trend analys. Kvaliteten på dessa mätningar kommer därför direkt påverka resultaten av dessa aktiviteter och därför vår uppfattning av nätverket och dess tjänster. I denna avhandling ger vi en systematisk översikt av datornätverks mätningar och en omfattande översikt av de faktorer som påverkar kvaliteten av prestanda parametrar som tas fram via mätningar. Detta görs genom ett nytt ramverks som beskriver de fyra moduler som påverkar mätningarnas kvalitet: generering, mätning, analys och visualisering. En av de stora källorna till kvalitets problem är noggrannheten på tidstämplar. Dessa tidstämplar beskriver när händelser skedde i nätverket. På grund av detta så presenterar vi en metod som kan uppskatta den tidstämpling noggrannhet som man kan få från mätverktyg, både hård och mjukvara. Metoden används för att utvärdera noggrannheten på några vanliga verktyg, två hårdvarubaserade system (Agilent J6800/J6830A och Endace DAG 3.5E) samt mjukvarubaserade system (Packet Capture Library). Vidare så diskuteras påverkan som analysen har på kvaliteten, och ett exempel ges på hur ett prestanda mått (bitrate) påverkas av mätsystem (hård/mjukvara) och analys metod. Avhandlingen innehåller dessutom utvärderingar av trafik generatorer, applikations mätningar och kvaliteten på mättningar gjorda med PING och J-OWAMP. Huvudslutsatsen i arbetet är att mätsystem och verktyg måste kalibreras, verifieras och valideras innan de används. Baserat på detta så presenterar vi en riktlinje över hur man gör detta.

As a part of the manufacturing process at the forging shop of Alleima AB in Sandviken, materials are heated in a furnace and then quenched in a quench tank. A temperature sensor in the outlet of the tank indicates the time when the temperature rises inside the quench tank. Since the cooling system is dynamic (has inertia), the temperature sensor registers a temperature rise with a delay. Considering the rapid change in the mechanical properties of hot materials, it is important to determine the exact time when the cooling begins. This project proposed a vision system-based automatic timestamp registration technique to facilitate the need. The proposed mechanism first detects the hot metal bars and then uses an event-based technique to determine the timestamp. Finally, the obtained timestamp has been compared with the temperature sensor measurement to determine the delay. This project uses the iba-system to perform the entire procedure. The video sequence is collected using ibaCapture and the image processing took place in ibaVision. The recorded timestamp is then transferred to ibaPDA for further analysis. The main goal is to combine temperature measurement and a computer vision system to automatically determine the delay registered by the temperature sensor. In addition to the proposed solution, this project analysed the image processing plug-in concept of ibaVision and its interface connection with other iba-modules such as ibaPDA and ibaCapture.