Analysis and Mitigation of Remote Side-Channel and Fault Attacks on the Electrical Level

In der fortlaufenden Miniaturisierung von integrierten Schaltungen werden physikalische Grenzen erreicht, wobei beispielsweise Einzelatomtransistoren eine mögliche untere Grenze für Strukturgrößen darstellen. Zudem ist die Herstellung der neuesten Generationen von Mikrochips heutzutage finanziell nur noch von großen, multinationalen Unternehmen zu stemmen. Aufgrund dieser Entwicklung ist Miniaturisierung nicht länger die treibende Kraft um die Leistung von elektronischen Komponenten weiter zu erhöhen. Stattdessen werden klassische Computerarchitekturen mit generischen Prozessoren weiterentwickelt zu heterogenen Systemen mit hoher Parallelität und speziellen Beschleunigern. Allerdings wird in diesen heterogenen Systemen auch der Schutz von privaten Daten gegen Angreifer zunehmend schwieriger. Neue Arten von Hardware-Komponenten, neue Arten von Anwendungen und eine allgemein erhöhte Komplexität sind einige der Faktoren, die die Sicherheit in solchen Systemen zur Herausforderung machen. Kryptografische Algorithmen sind oftmals nur unter bestimmten Annahmen über den Angreifer wirklich sicher. Es wird zum Beispiel oft angenommen, dass der Angreifer nur auf Eingaben und Ausgaben eines Moduls zugreifen kann, während interne Signale und Zwischenwerte verborgen sind. In echten Implementierungen zeigen jedoch Angriffe über Seitenkanäle und Faults die Grenzen dieses sogenannten Black-Box-Modells auf. Während bei Seitenkanalangriffen der Angreifer datenabhängige Messgrößen wie Stromverbrauch oder elektromagnetische Strahlung ausnutzt, wird bei Fault Angriffen aktiv in die Berechnungen eingegriffen, und die falschen Ausgabewerte zum Finden der geheimen Daten verwendet. Diese Art von Angriffen auf Implementierungen wurde ursprünglich nur im Kontext eines lokalen Angreifers mit Zugriff auf das Zielgerät behandelt. Jedoch haben bereits Angriffe, die auf der Messung der Zeit für bestimmte Speicherzugriffe basieren, gezeigt, dass die Bedrohung auch durch Angreifer mit Fernzugriff besteht. In dieser Arbeit wird die Bedrohung durch Seitenkanal- und Fault-Angriffe über Fernzugriff behandelt, welche eng mit der Entwicklung zu mehr heterogenen Systemen verknüpft sind. Ein Beispiel für neuartige Hardware im heterogenen Rechnen sind Field-Programmable Gate Arrays (FPGAs), mit welchen sich fast beliebige Schaltungen in programmierbarer Logik realisieren lassen. Diese Logik-Chips werden bereits jetzt als Beschleuniger sowohl in der Cloud als auch in Endgeräten eingesetzt. Allerdings wurde gezeigt, wie die Flexibilität dieser Beschleuniger zur Implementierung von Sensoren zur Abschätzung der Versorgungsspannung ausgenutzt werden kann. Zudem können durch eine spezielle Art der Aktivierung von großen Mengen an Logik Berechnungen in anderen Schaltungen für Fault Angriffe gestört werden. Diese Bedrohung wird hier beispielsweise durch die Erweiterung bestehender Angriffe weiter analysiert und es werden Strategien zur Absicherung dagegen entwickelt

International Public Procurement Agreements - Problems of Implemetations in Switzerland

Öffentliche Beschaffung, Reform, Public Choice, Wohlfahrtstheorie, Schweiz, Public Procurement, Welfare economics, Switzerland

An Evaluation of Input Controls for In-Car Interactions

The way drivers operate in-car systems is rapidly changing as traditional physical controls, such as buttons and dials, are being replaced by touchscreens and touch-sensing surfaces. This has the potential to increase driver distraction and error as controls may be harder to find and use. This paper presents an in-car, on the road driving study which examined three key types of input controls to investigate their effects: a physical dial, pressure-based input on a touch surface and touch input on a touchscreen. The physical dial and pressure-based input were also evaluated with and without haptic feedback. The study was conducted with users performing a list-based targeting task using the different controls while driving on public roads. Eye-gaze was recorded to measure distraction from the primary task of driving. The results showed that target accuracy was high across all input methods (greater than 94%). Pressure-based targeting was the slowest while directly tapping on the targets was the faster selection method. Pressure-based input also caused the largest number of glances towards to the touchscreen but the duration of each glance was shorter than directly touching the screen. Our study will enable designers to make more appropriate design choices for future in-car interactions

The Reanalysis of the ROSAT Data of GQ Mus (1983) Using White Dwarf Atmosphere Emission Models

The analyses of X-ray emission from classical novae during the outburst stage have shown that the soft X-ray emission below 1 keV, which is thought to originate from the photosphere of the white dwarf, is inconsistent with the simple blackbody model of emission. Thus, $ROSAT$ Position Sensitive Proportional Counter (PSPC) archival data of the classical novae GQ Mus 1983 (GQ Mus) have been reanalyzed in order to understand the spectral development in the X-ray wavelengths during the outburst stage. The X-ray spectra are fitted with the hot white dwarf atmosphere emission models developed for the remnants of classical novae near the Eddington luminosity. The post-outburst X-ray spectra of the remnant white dwarf is examined in the context of evolution on the Hertzsprung-Russell diagram using C-O enhanced atmosphere models. The data obtained in 1991 August (during the ROSAT All Sky Survey) indicate that the effective temperature is kT_e<54 eV (<6.2x10^5 K). The 1992 February data show that the white dwarf had reached an effective temperature in the range 38.3-43.3 eV (4.4-5.1x10^5 K) with an unabsorbed X-ray flux (i.e., $\sim$ bolometric flux) between 2.5x10^-9 and 2.3x10^-10 erg s^-1 cm^-2. We show that the H burning at the surface of the WD had most likely ceased at the time of the X-ray observations. Only the 1991 August data show evidence for ongoing H burning.Comment: 17 pages and 3 figures. Accepted to be published in MNRA

The role of duty-based ethics in public relations: an ethical justification model for the actions of crisis communicators

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on November 11, 2008)Includes bibliographical references.Thesis (M.A.) University of Missouri-Columbia 2007.Dissertations, Academic -- University of Missouri--Columbia -- Journalism.This thesis explores how duty-based ethics can aid in explaining how public relations professional employed by corporations communicate with external publics, especially when organizations are faced with crises. A content analysis examined whether ethical duties were mentioned in various types of messages by four organizations., two non-profit and two profit corporations, in times of .non-crisis. and crisis. The analysis examined publicly available documents, which contained official communication related to the organizational culture and news stories published in four newspapers during times of crisis. Analysis found that autonomy and respect from the dominant coalition enabled public relations, practitioners to act as ethical advocates. In addition, public communication follows a crisis life cycle. Content analysis also found that Ross's six ethical duties could be plausible evaluative criteria for determining the ethical tone of communication. Identifying the dominant ethical duties for each case established the ethical tone for the messages. When there was no crisis, all six of Ross's ethical duties were expressed in the messages through mission statements and descriptions of corporate culture. In times of crisis, often the message is changed to reflect the law or only some ethical duties. The change of message suggests that ethical communication can be accomplished in several ways, which supports a fundamental claim of contingency theory

Modeling CHANDRA Low Energy Transmission Grating Spectrometer Observations of Classical Novae with PHOENIX. I. V4743 Sagittarii

We use the PHOENIX code package to model the X-ray spectrum of Nova V4743 Sagittarii observed with the LETGS onboard the Chandra satellite on March 2003. Our atmosphere models are 1D spherical, expanding, line blanketed, and in full NLTE. To analyze nova atmospheres and related systems with an underlying nuclear burning envelope at X-ray wavelengths, it was necessary to update the code with new microphysics, as discussed in this paper. We demonstrate that the X-ray emission is dominated by thermal bremsstrahlung and that the hard X-rays are dominated by Fe and N absorption. The best fit to the observation is provided at a temperature of T_eff = 5.8 x 10^5 K, with L_bol = 50 000 L_sun. The models are calculated for solar abundances. It is shown that the models can be used to determine abundances in the nova ejecta.Comment: 8 pages, 6 figures, accepted for publication in Astronomy & Astrophysic

Expanding atmosphere models for SSS spectra of novae

Super Soft Source (SSS) spectra are powered by nuclear burning on the surface of a white dwarf. The released energy causes a radiatively-driven wind that leads to a radially extended atmosphere around the white dwarf. Significant blue shifts in photospheric absorption lines are found in the spectra of novae during their SSS phase, being an evidence of continued mass loss in this phase. We present spherically symmetric PHOENIX models that account for the expansion of the ejecta. A comparison to a plane parallel, hydrostatic atmosphere model demonstrates that the mass loss can have a significant impact on the model spectra. The dynamic model yields less pronounced absorption edges, and harder X-ray spectra are the result. Therefore, lower effective temperatures are needed to explain the observed spectra. Although both types of models are yet to be fine-tuned in order to accurately determine best fit parameters, the implications on the chemical abundances are going in opposite directions. With the expanding models the requirement for strong depletion of the crucial elements that cause these edges is now avoidable.Comment: 4 pages, accepted for A

Observational Evidence for Expansion in the SSS spectra of Novae

For several novae, a bright X-ray source with a spectrum resembling the class of Super Soft X-ray Sources (SSS) has been observed a few weeks to months after outburst. Novae are powered by explosive nuclear burning on the surface of a white dwarf, and enough energy is produced to power a radiatively driven wind. Owing to the evolution of the opacity of the ejecta, the observable spectrum gradually shifts from optical to soft X-rays (SSS phase). It has sometimes been assumed that at the beginning of the SSS phase no more mass loss occurs. However, high-resolution X-ray spectra of some novae have shown highly blue-shifted absorption lines, indicating a significant expansion. In this paper, I show that all novae that have been observed with X-ray gratings during their SSS phase show significant blue shifts. I argue that all models that attempt to explain the X-ray bright SSS phase have to accommodate the continued expansion of the ejecta.Comment: 4 pages, accepted for Astronomische Nachrichte