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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An Attack and a Defence in the Context of Hardware Security

Imeson, Frank 16 May 2013 (has links)
The security of digital Integrated Circuits (ICs) is essential to the security of a computer system that comprises them. We present an improved attack on computer hardware that avoids known defence mechanisms and as such raises awareness for the need of new and improved defence mechanisms. We also present a new defence method for securing computer hardware against modifications from untrusted manufacturing facilities, which is of concern since manufacturing is increasingly outsourced. We improve upon time triggered based backdoors, inserted maliciously in hardware. Prior work has addressed deterministic timer-based triggers — those that are designed to trigger at a specific time with probability 1. We address open questions related to the feasibility of realizing non-deterministic timer-based triggers in hardware — those that are designed with a random component. We show that such timers can be realized in hardware in a manner that is impractical to detect or disable using existing countermeasures of which we are aware. We discuss our design, implementation and analysis of such a timer. We show that the attacker can have surprisingly fine-grained control over the time-window within which the timer triggers. From the attacker’s standpoint our non-deterministic timer has key advantages over traditional timer designs. For example the hardware footprint is smaller which increases the chances of avoiding detection. Also our timer has a much smaller time-window for which a volatile state needs to be maintained which in turn makes the power reset defence mechanisms less effective. Our proposed defence mechanism addresses the threat of a malicious agent at the IC foundry who has information of the circuit and inserts covert, malicious circuitry. The use of 3D IC technology has been suggested as a possible technique to counter this threat. However, to our knowledge, there is no prior work on how such technology can be used effectively. We propose a way to use 3D IC technology for security in this context. Specifically, we obfuscate the circuit by lifting wires to a trusted tier, which is fabricated separately. We provide a precise notion of security that we call k-security and point out that it has interesting similarities and important differences from k-anonymity. We also give a precise specification of the underlying computational problems and their complexity and discuss a comprehensive empirical assessment with benchmark circuits that highlight the security versus cost trade-offs introduced by 3D IC based circuit obfuscation.
2

Proposta de hardware para aquisição simultânea multicanal e sua aplicação na localização de fontes sonoras/

Ferreira, M. L. C. January 2015 (has links) (PDF)
Dissertação (Mestrado em Engenharia Elétrica) - Centro Universitário da FEI, São Bernardo do Campo, 2015
3

A Graphical Approach to Testing Real-Time Embedded Devices

Day, Steven M 01 June 2009 (has links)
Software Testing is both a vital and expensive part of the software development lifecycle. Improving the testing process has the potential for large returns. Current testing methodologies used to test real-time embedded devices are examined and the weaknesses in them are exposed. This leads to the introduction of a new graphical testing methodology based on flowcharts. The new approach is both a visual test creation program and an automated execution engine that together frame a new way of testing. The new methodology incorporates flow-based diagrams, visual layouts, and simple execution rules to improve upon traditional testing approaches. The new methodology is evaluated against other methodologies and is shown to provide significant improvements in the area of software testing.
4

Systematic Analysis and Methodologies for Hardware Security

Moein, Samer 18 December 2015 (has links)
With the increase in globalization of Integrated Circuit (IC) design and production, hardware trojans have become a serious threat to manufacturers as well as consumers. These trojans could be intensionally or accidentally embedded in ICs to make a system vulnerable to hardware attacks. The implementation of critical applications using ICs makes the effect of trojans an even more serious problem. Moreover, the presence of untrusted foundries and designs cannot be eliminated since the need for ICs is growing exponentially and the use of third party software tools to design the circuits is now common. In addition if a trusted foundry for fabrication has to be developed, it involves a huge investment. Therefore, hardware trojan detection techniques are essential. Very Large Scale Integration (VLSI) system designers must now consider the security of a system against internal and external hardware attacks. Many hardware attacks rely on system vulnerabilities. Moreover, an attacker may rely on deprocessing and reverse engineering to study the internal structure of a system to reveal the system functionality in order to steal secret keys or copy the system. Thus hardware security is a major challenge for the hardware industry. Many hardware attack mitigation techniques have been proposed to help system designers build secure systems that can resist hardware attacks during the design stage, while others protect the system against attacks during operation. In this dissertation, the idea of quantifying hardware attacks, hardware trojans, and hardware trojan detection techniques is introduced. We analyze and classify hardware attacks into risk levels based on three dimensions Accessibility/Resources/Time (ART). We propose a methodology and algorithms to aid the attacker/defender to select/predict the hardware attacks that could use/threaten the system based on the attacker/defender capabilities. Because many of these attacks depends on hardware trojans embedded in the system, we propose a comprehensive hardware trojan classification based on hardware trojan attributes divided into eight categories. An adjacency matrix is generated based on the internal relationship between the attributes within a category and external relationship between attributes in different categories. We propose a methodology to generate a trojan life-cycle based on attributes determined by an attacker/defender to build/investigate a trojan. Trojan identification and severity are studied to provide a systematic way to compare trojans. Trojan detection identification and coverage is also studied to provide a systematic way to compare detection techniques and measure their e effectiveness related to trojan severity. We classify hardware attack mitigation techniques based on the hardware attack risk levels. Finally, we match these techniques to the attacks the could countermeasure to help defenders select appropriate techniques to protect their systems against potential hardware attacks. / Graduate / 0544 / 0984 / samerm@uvic.ca
5

tithu

udeuid, aiaqja 29 May 2017 (has links)
Submitted by admin admin (admin@admin.n) on 2017-05-29T13:40:24Z No. of bitstreams: 1 mysql-tutorial-excerpt-5.5-en.pdf: 196134 bytes, checksum: b70a6c8098b88d4fd210eab81596fec0 (MD5) / Made available in DSpace on 2017-05-29T13:40:25Z (GMT). No. of bitstreams: 1 mysql-tutorial-excerpt-5.5-en.pdf: 196134 bytes, checksum: b70a6c8098b88d4fd210eab81596fec0 (MD5) Previous issue date: 2017-05-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / akekaeuk / kaeukeuk
6

teste campus

udeuid, aiaqja 31 May 2017 (has links)
Submitted by admin admin (admin@admin.n) on 2017-05-31T12:02:08Z No. of bitstreams: 1 mysql-tutorial-excerpt-5.5-en.pdf: 196134 bytes, checksum: b70a6c8098b88d4fd210eab81596fec0 (MD5) / Made available in DSpace on 2017-05-31T12:02:09Z (GMT). No. of bitstreams: 1 mysql-tutorial-excerpt-5.5-en.pdf: 196134 bytes, checksum: b70a6c8098b88d4fd210eab81596fec0 (MD5) Previous issue date: 2017-05-31 / aaooeeuu / aaooeeuu
7

Adaptive memory hierarchies for next generation tiled microarchitectures

Herrero Abellanas, Enric 05 July 2011 (has links)
Les últimes dècades el rendiment dels processadors i de les memòries ha millorat a diferent ritme, limitant el rendiment dels processadors i creant el conegut memory gap. Sol·lucionar aquesta diferència de rendiment és un camp d'investigació d'actualitat i que requereix de noves sol·lucions. Una sol·lució a aquest problema són les memòries “cache”, que permeten reduïr l'impacte d'unes latències de memòria creixents i que conformen la jerarquia de memòria. La majoria de d'organitzacions de les “caches” estan dissenyades per a uniprocessadors o multiprcessadors tradicionals. Avui en dia, però, el creixent nombre de transistors disponible per xip ha permès l'aparició de xips multiprocessador (CMPs). Aquests xips tenen diferents propietats i limitacions i per tant requereixen de jerarquies de memòria específiques per tal de gestionar eficientment els recursos disponibles. En aquesta tesi ens hem centrat en millorar el rendiment i la eficiència energètica de la jerarquia de memòria per CMPs, des de les “caches” fins als controladors de memòria. A la primera part d'aquesta tesi, s'han estudiat organitzacions tradicionals per les “caches” com les privades o compartides i s'ha pogut constatar que, tot i que funcionen bé per a algunes aplicacions, un sistema que s'ajustés dinàmicament seria més eficient. Tècniques com el Cooperative Caching (CC) combinen els avantatges de les dues tècniques però requereixen un mecanisme centralitzat de coherència que té un consum energètic molt elevat. És per això que en aquesta tesi es proposa el Distributed Cooperative Caching (DCC), un mecanisme que proporciona coherència en CMPs i aplica el concepte del cooperative caching de forma distribuïda. Mitjançant l'ús de directoris distribuïts s'obté una sol·lució més escalable i que, a més, disposa d'un mecanisme de marcatge més flexible i eficient energèticament. A la segona part, es demostra que les aplicacions fan diferents usos de la “cache” i que si es realitza una distribució de recursos eficient es poden aprofitar els que estan infrautilitzats. Es proposa l'Elastic Cooperative Caching (ElasticCC), una organització capaç de redistribuïr la memòria “cache” dinàmicament segons els requeriments de cada aplicació. Una de les contribucions més importants d'aquesta tècnica és que la reconfiguració es decideix completament a través del maquinari i que tots els mecanismes utilitzats es basen en estructures distribuïdes, permetent una millor escalabilitat. ElasticCC no només és capaç de reparticionar les “caches” segons els requeriments de cada aplicació, sinó que, a més a més, és capaç d'adaptar-se a les diferents fases d'execució de cada una d'elles. La nostra avaluació també demostra que la reconfiguració dinàmica de l'ElasticCC és tant eficient que gairebé proporciona la mateixa taxa de fallades que una configuració amb el doble de memòria.Finalment, la tesi es centra en l'estudi del comportament de les memòries DRAM i els seus controladors en els CMPs. Es demostra que, tot i que els controladors tradicionals funcionen eficientment per uniprocessadors, en CMPs els diferents patrons d'accés obliguen a repensar com estan dissenyats aquests sistemes. S'han presentat múltiples sol·lucions per CMPs però totes elles es veuen limitades per un compromís entre el rendiment global i l'equitat en l'assignació de recursos. En aquesta tesi es proposen els Thread Row Buffers (TRBs), una zona d'emmagatenament extra a les memòries DRAM que permetria guardar files de dades específiques per a cada aplicació. Aquest mecanisme permet proporcionar un accés equitatiu a la memòria sense perjudicar el seu rendiment global. En resum, en aquesta tesi es presenten noves organitzacions per la jerarquia de memòria dels CMPs centrades en la escalabilitat i adaptativitat als requeriments de les aplicacions. Els resultats presentats demostren que les tècniques proposades proporcionen un millor rendiment i eficiència energètica que les millors tècniques existents fins a l'actualitat. / Processor performance and memory performance have improved at different rates during the last decades, limiting processor performance and creating the well known "memory gap". Solving this performance difference is an important research field and new solutions must be proposed in order to have better processors in the future. Several solutions exist, such as caches, that reduce the impact of longer memory accesses and conform the system memory hierarchy. However, most of the existing memory hierarchy organizations were designed for single processors or traditional multiprocessors. Nowadays, the increasing number of available transistors has allowed the apparition of chip multiprocessors, which have different constraints and require new ad-hoc memory systems able to efficiently manage memory resources. Therefore, in this thesis we have focused on improving the performance and energy efficiency of the memory hierarchy of chip multiprocessors, ranging from caches to DRAM memories. In the first part of this thesis we have studied traditional cache organizations such as shared or private caches and we have seen that they behave well only for some applications and that an adaptive system would be desirable. State-of-the-art techniques such as Cooperative Caching (CC) take advantage of the benefits of both worlds. This technique, however, requires the usage of a centralized coherence structure and has a high energy consumption. Therefore we propose the Distributed Cooperative Caching (DCC), a mechanism to provide coherence to chip multiprocessors and apply the concept of cooperative caching in a distributed way. Through the usage of distributed directories we obtain a more scalable solution and, in addition, has a more flexible and energy-efficient tag allocation method. We also show that applications make different uses of cache and that an efficient allocation can take advantage of unused resources. We propose Elastic Cooperative Caching (ElasticCC), an adaptive cache organization able to redistribute cache resources dynamically depending on application requirements. One of the most important contributions of this technique is that adaptivity is fully managed by hardware and that all repartitioning mechanisms are based on distributed structures, allowing a better scalability. ElasticCC not only is able to repartition cache sizes to application requirements, but also is able to dynamically adapt to the different execution phases of each thread. Our experimental evaluation also has shown that the cache partitioning provided by ElasticCC is efficient and is almost able to match the off-chip miss rate of a configuration that doubles the cache space. Finally, we focus in the behavior of DRAM memories and memory controllers in chip multiprocessors. Although traditional memory schedulers work well for uniprocessors, we show that new access patterns advocate for a redesign of some parts of DRAM memories. Several organizations exist for multiprocessor DRAM schedulers, however, all of them must trade-off between memory throughput and fairness. We propose Thread Row Buffers, an extended storage area in DRAM memories able to store a data row for each thread. This mechanism enables a fair memory access scheduling without hurting memory throughput. Overall, in this thesis we present new organizations for the memory hierarchy of chip multiprocessors which focus on the scalability and of the proposed structures and adaptivity to application behavior. Results show that the presented techniques provide a better performance and energy-efficiency than existing state-of-the-art solutions.
8

A High-Speed Reconfigurable System for Ultrasound Research

Wall, Kieran 13 December 2010 (has links)
Many opportunities exist in medical ultrasound research for experimenting with novel designs, both of transducers and of signal processing techniques. However any experiment must have a reliable platform on which to develop these techniques. In my thesis work, I have designed, built, and tested a high-speed reconfigurable ultrasound beamforming platform. The complete receive beamformer system described in this thesis consists of hardware, firmware, and software components. All of these components work together to provide a platform for beamforming that is expandable, high-speed, and robust. The complexity of the operations being performed is hidden from the user by a simple to use and accessible software interface. Existing beamformer hardware is usually designed for real-time 2D image formation often using serial processing. The platform I built uses parallel processing in order to process ultrasound images 100 times faster than conventional systems. Conventional hardware is locked to a single or small number of similar transducers, while my design can be on-the-fly reprogrammed to work with nearly any transducer type. The system is also expandable to handle any size of device, while conventional systems can only handle a fixed number of device channels. The software I have created interfaces with the hardware and firmware components to provide an easy way to make use of the system’s reconfigurability. It also delivers a platform that can be simply expanded to host post-processing or signal analysis software to further fulfill a researcher’s needs. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2010-12-10 11:23:01.961
9

High-throughput local area network access for INMOS transputers

Peel, R. M. A. January 1995 (has links)
This thesis presents the design of an Ethernet local-area network interface for embedded transputer systems. It is based upon parallel software which manages the TCP/IP family of protocols, passing packets between a single transputer, which connects to the network, and application processes which run on an arbitrary number of other transputers. The different layers of the protocol processing - Ethernet control, IP and TCP are all performed in separate parallel processes. Extra routing processors, arranged in a tree configuration, provide access to the lower IP and Ethernet layers from as many TCP and application processes as desired. Investigation of the processor utilisation and channel throughput of each of the parallel processes has led to the rejection of hardware-assistance in the form of a complex shared-memory, multi-processor architecture. Instead, a double pipeline of processes, running on a small pipeline of transputers, communicate exclusively using the transputers' serial links. This scheme is shown to provide good load balancing and to be a cost-effective way of exchanging traffic between a transputer application and a user process running on a high-performance workstation at data rates of over 950 kbytes/second - almost the entire available bandwidth of a 10 Mbit/sec Ethernet. All software is written in the occam programming language. As well as presenting the design of the protocol software, the thesis includes performance measurements and reports on two applications which were built upon the initial work. These are a networked implementation of the INMOS Iserver, which allows access to transputers from anywhere on the network, and an embedded instrumentation system which pre-processes data from an ion microbeam and passes part-analysed results to a conventional workstation for display, archiving and user control of the experiment.
10

Fault tolerance in distributed real-time computer systems

Baba, Mohd Dani January 1996 (has links)
A distributed real-time computer system consists of several processing nodes interconnected by communication channels. In a safety critical application, the real-time system should maintain timely and dependable services despite component failures or transient overloads due to changes in application environment. When a component fails or an overload occurs, the hard real-time tasks may miss their timing constraints, and it is desired that the system to degrade in a graceful, predictable manner. The approach adopted to the problem in this thesis is by integrating the resource scheduling with fault tolerance mechanism. This thesis provides a basis for the modelling and design of an adaptive fault tolerant distributed real-time computer system. The main issue is to determine a priori the worst case timing response of the given hard realtime tasks. In this thesis the worst case timing response of the given hard real-time task of the distributed system using the Controller Area Network (CAN) communication protocol is evaluated as to whether they can satisfy their timing deadlines. In a hard real-time system, the task scheduling is the most critical problem since the scheduling strategy ensures that tasks meet their deadlines. In this thesis several fixed priority scheduling schemes are evaluated to select the most efficient scheduler in terms of the bus utilisation and access time. Static scheduling is used as it can be considered to be most appropriate for safety critical applications since the schedulability can easily be verified. Furthermore for a typical industrial application, the hard real-time system has to be adaptable to accommodate changes in the system or application requirements. This .goal of flexibility can be achieved by integrating the static scheduler using an imprecise computation technique with the fault tolerant mechanism which uses active redundant components.

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