Showing papers by "Münster University of Applied Sciences published in 2018"

Attacking Deterministic Signature Schemes Using Fault Attacks

Abstract: Many digital signature schemes rely on random numbers that are unique and non-predictable per signature. Failures of random number generators may have catastrophic effects such as compromising private signature keys. In recent years, many widely-used cryptographic technologies adopted deterministic signature schemes because they are presumed to be safer to implement. In this paper, we analyze the security of deterministic ECDSA and EdDSA signature schemes and show that the elimination of random number generators in these schemes enables new kinds of fault attacks. We formalize these attacks and introduce practical attack scenarios against EdDSA using the Rowhammer fault attack. EdDSA is used in many widely used protocols such as TLS, SSH, and IPSec, and we show that these protocols are not vulnerable to our attack. We formalize the necessary requirements of protocols using these deterministic signature schemes to be vulnerable, and discuss mitigation strategies and their effect on fault attacks against deterministic signature schemes.

Efail: Breaking S/MIME and OpenPGP Email Encryption using Exfiltration Channels

Abstract: OpenPGP and S/MIME are the two prime standards for providing end-to-end security for emails. We describe novel attacks built upon a technique we call malleability gadgets to reveal the plaintext of encrypted emails. We use CBC/CFB gadgets to inject malicious plaintext snippets into encrypted emails. These snippets abuse existing and standard conforming backchannels to exfiltrate the full plaintext after decryption. We describe malleability gadgets for emails using HTML, CSS, and X.509 functionality. The attack works for emails even if they were collected long ago, and it is triggered as soon as the recipient decrypts a single maliciously crafted email from the attacker. We devise working attacks for both OpenPGP and S/MIME encryption, and show that exfiltration channels exist for 23 of the 35 tested S/MIME email clients and 10 of the 28 tested OpenPGP email clients. While it is advisable to update the OpenPGP and S/MIME standards to fix these vulnerabilities, some clients had even more severe implementation flaws allowing straightforward exfiltration of the plaintext.

Photoluminescence and energy transfer behavior of narrow band red light emitting Li3Ba2Tb3(MoO4)8:Eu3+

Abstract: This work concerns the polycrystalline red emitting solid state compound Li3Ba2(Tb1−xEux)3(MoO4)8, from which a series of powder samples was prepared by a conventional solid-state reaction. The phase formation of the samples was investigated by X-ray diffraction which revealed the formation of a solid solution without a miscibility gap. Photoluminescence (PL) spectra and decay curves were recorded as a function of Tb3+ and Eu3+ concentration and temperature. It turned out that the external quantum efficiency of Eu3+ photoluminescence is between 30 and 80%, while the highest quantum yield is achieved for about 60% Tb3+. An increase of emission intensity can be realized by co-doping of Eu3+ and Tb3+. Moreover, the emission has a luminous efficacy of 275 lm Wopt−1 which is a distinct advantage over the widely applied Mn4+ activated fluorides. The time dependent photoluminescence as a function of Tb3+ concentration demonstrates the presence of an efficient energy transfer from Tb3+ to Eu3+. Temperature dependent PL measurements revealed that Li3Ba2(Tb1−xEux)3(MoO4)8 loses just 20% of PL efficiency up to 400 K. Therefore, the investigated phosphors are attractive for application in pcLEDs. It is finally demonstrated that the application of a Eu3+/Tb3+ co-doped ceramic disc is useful for the colour conversion of a blue emitting LED with a higher conversion rate compared to Li3Ba2(La1−xEux)3(MoO4)8.

Effect of a Sodium and Calcium DL-β-Hydroxybutyrate Salt in Healthy Adults.

Abstract: Background. Ketone body therapy and supplementation are of high interest for several medical and nutritional fields. The intake of ketone bodies is often discussed in relation to rare metabolic diseases, such as multiple acyl-CoA dehydrogenase deficiency (MADD), that have no alternatives for treatment. Case reports showed positive results of therapy using ketone bodies. The number of ketone body salts offered on the wellness market is increasing steadily. More information on the kinetics of intake, safety, and tolerance of these products is needed. Methods. In a one-dose kinetic study, six healthy subjects received an intervention (0.5 g/kg bw) using a commercially available ketone body supplement. The supplement contained a mixture of sodium and calcium D-/L-β-hydroxybutyrate (βHB) as well as food additives. The blood samples drawn in the study were tested for concentrations of D-βHB, glucose, and electrolytes, and blood gas analyses were done. Data on sensory evaluation and observed side effects of the supplement were collected. The product also went through chemical food analysis. Results. The supplement led to a significant increase of D-βHB concentration in blood 2.5 and 3 h after oral intake ( ). The first significant effect was measured after 2 h with a mean value of 0.598 ± 0.300 mmol/L at the peak, which was recorded at 2.5 h. Changes in serum electrolytes and BGA were largely unremarkable. Taking the supplement was not without side effects. One subject dropped out due to gastrointestinal symptoms and two others reported similar but milder problems. Conclusions. Intake of a combination of calcium and sodium D-/L-βHB salt shows a slow resorption with a moderate increase of D-βHB in serum levels. An influence of βHB salts on acid-base balance could not be excluded by this one-dose study. Excessive regular consumption without medical observation is not free of adverse effects. The tested product can therefore not be recommended unconditionally.

Enhancing Psychosis-Spectrum Nosology Through an International Data Sharing Initiative.

Abstract: The latent structure of schizotypy and psychosis-spectrum symptoms remains poorly understood. Furthermore, molecular genetic substrates are poorly defined, largely due to the substantial resources required to collect rich phenotypic data across diverse populations. Sample sizes of phenotypic studies are often insufficient for advanced structural equation modeling approaches. In the last 50 years, efforts in both psychiatry and psychological science have moved toward (1) a dimensional model of psychopathology (eg, the current Hierarchical Taxonomy of Psychopathology [HiTOP] initiative), (2) an integration of methods and measures across traits and units of analysis (eg, the RDoC initiative), and (3) powerful, impactful study designs maximizing sample size to detect subtle genomic variation relating to complex traits (the Psychiatric Genomics Consortium [PGC]). These movements are important to the future study of the psychosis spectrum, and to resolving heterogeneity with respect to instrument and population. The International Consortium of Schizotypy Research is composed of over 40 laboratories in 12 countries, and to date, members have compiled a body of schizotypy- and psychosis-related phenotype data from more than 30000 individuals. It has become apparent that compiling data into a protected, relational database and crowdsourcing analytic and data science expertise will result in significant enhancement of current research on the structure and biological substrates of the psychosis spectrum. The authors present a data-sharing infrastructure similar to that of the PGC, and a resource-sharing infrastructure similar to that of HiTOP. This report details the rationale and benefits of the phenotypic data collective and presents an open invitation for participation.

Warm-white LED with ultra high luminous efficacy due to sensitisation of Eu3+ photoluminescence by the uranyl moiety in K4(UO2)Eu2(Ge2O7)2

Abstract: Narrow band red emitting phosphors have a great potential to boost the luminous efficacy of warm-white LEDs if their emission spectrum peaks between 610–630 nm and re-absorption of light emitted by the green to yellow LED phosphor, e.g. LuAG:Ce or YAG:Ce, is limited. Therefore, Mn4+ doped fluoride type materials dominate the chase for such novel phosphors. However, Eu3+ activated materials are of interest too, but their application is hampered by the very low absorption cross section in the near UV and particularly in the blue spectral range. Therefore, this work deals with the sensitisation of Eu3+ photoluminescence by uranyl cations in K4(UO2)Eu2(Ge2O7)2. It turned out that this approach yields a phosphor with a luminous efficacy of 260 lm Wopt−1 with a CIE1931 colour point of x = 0.647 and y = 0.349. For the first time a phosphor converted 2700 K (In,Ga)N LED comprising a Eu3+ activated phosphor as the red emitter has been reported. K4(UO2)Eu2(Ge2O7)2 enables a CRI of at least 85 with an impressive luminous efficacy of around 360 lm Wopt−1.

Running with drones: desired services and control gestures

Abstract: Due to their mobility, drones are in principle well-suited to support runners, but it is not yet clear, which services runners desire and how they would want to control them. We, therefore, conducted an online survey (N=22) to identify desired services and then asked runners to produce control gestures for those services in a realistic outdoor elicitation study (N=16). Our main contributions: (1) are a set of services that runners would want from a drone, such as taking a picture or calling the police; (2) a set of intuitive gestures for controlling flight actions and drone functions such as forming a square with both hands; and (3) insights into how runners propose gestures. We also evaluate and discuss the idea of modulating gestures on running movement as well as the tension between intuitiveness of a gesture and how much it interferes with the running movement.

Statistical Distribution of TSS Event Loads from Small Urban Environments

Abstract: Results from a long-term stormwater quality monitoring program were used to derive total suspended solids (TSS) event load distributions at four small urban environments (flat roof, parking lot, residential catchment, high traffic street). Theoretical distribution functions were fitted to the empirical distribution functions obtained. Parameters of the theoretical distribution functions were optimized with respect to a likelihood function to get both optimized parameters and standard errors. Kolmogorov-Smirnov and Anderson-Darling test statistics were applied to assess the goodness-of-fit between empirical and theoretical distribution. The lognormal distribution function was found to be most expressive to approximate empirical TSS event load distributions at all sites. However, the goodness-of-fit of the statistical model strongly depends on the number of events available. Based on the results of a Monte-Carlo-based resampling strategy, around 40 events should be considered.

Bedarf und Qualität von Beratung in der Langzeitpflege

Abstract: Hintergrund Zur Unterstutzung pflegebedurftiger Menschen und ihrer Angehorigen existiert in Deutschland eine breite Beratungslandschaft, die sich verschiedenen Beratungsanlassen widmet. Dabei besteht ein Mangel an Qualitatskriterien, die sich an den Beratungsbedarfen der Nutzer/-innen orientieren.

Conditions where random phase approximation becomes exact in the high-density limit

Abstract: It is shown that, in $d$-dimensional systems, the vertex corrections beyond the random phase approximation (RPA) or $GW$ approximation scales with the power $d\ensuremath{-}\ensuremath{\beta}\ensuremath{-}\ensuremath{\alpha}$ of the Fermi momentum if the relation between Fermi energy and Fermi momentum is ${\ensuremath{\epsilon}}_{\mathrm{f}}\ensuremath{\sim}{p}_{\mathrm{f}}^{\ensuremath{\beta}}$ and the interacting potential possesses a momentum power law of $\ensuremath{\sim}{p}^{\ensuremath{-}\ensuremath{\alpha}}$. The condition $d\ensuremath{-}\ensuremath{\beta}\ensuremath{-}\ensuremath{\alpha}l0$ specifies systems where RPA is exact in the high-density limit. The one-dimensional structure factor is found to be the interaction-free one in the high-density limit for contact interaction. A cancellation of RPA and vertex corrections render this result valid up to second order in contact interaction. For finite-range potentials of cylindrical wires a large-scale cancellation appears and is found to be independent of the width parameter of the wire. The proposed high-density expansion agrees with the quantum Monte Carlo simulations.

Optimal control problems with time delays: Two case studies in biomedicine

Abstract: There exists an extensive literature on delay differential models in biology and biomedicine, but only a few papers study such models in the framework of optimal control theory. In this paper, we consider optimal control problems with multiple time delays in state and control variables and present two applications in biomedicine. After discussing the necessary optimality conditions for delayed optimal control problems with control-state constraints, we propose discretization methods by which the delayed optimal control problem is transformed into a large-scale nonlinear programming problem. The first case study is concerned with the delay differential model in [ 21 ] describing the tumour-immune response to a chemo-immuno-therapy. Assuming $ L^1$-type objectives, which are linear in control, we obtain optimal controls of bang-bang type. In the second case study, we introduce a control variable in the delay differential model of Hepatitis B virus infection developed in [ 7 ]. For $ L^1$-type objectives we obtain extremal controls of bang-bang type.

Properties Design: Prediction and Experimental Validation of the Luminescence Properties of a New EuII -Based Phosphor.

Abstract: A theoretical model that allows to predict, for the first time, the luminescence properties of a new phosphor (BaSnSi3 O9 :Eu2+ ) is presented The predicted emission wavelength, 488 nm with a 64 nm bandwidth, was confirmed by subsequent experimental work The method consists in a multi-electron Hamiltonian parametrized from ab initio calculations The luminescence properties of other similar compounds (ie, BaHfSi3 O9 :Eu2+ and BaZrSi3 O9 :Eu2+ ), for which there is already experimental information, were also correctly reproduced

A benefit segmentation approach for innovation-oriented university-business collaboration

Abstract: Increasing competition in the light of globalisation imposes challenges on both academia and businesses. Universities have to compete for additional financial means, while companies, particularly in high technology business environments, are facing a stronger pressure to innovate. Universities seek to deal with this situation by academic engagement, hereby providing external research support for businesses. Relying on the market segmentation approach, promoting beneficial exchange relations between academia and businesses enables the integration of both perspectives and may contribute to solving current challenges. Transferring the segmentation approach and the customer benefit perspective to university-business collaboration (UBC), this paper develops a multi-step segmentation framework aimed at identifying research customer segments in technical textile industries in Western Europe. This novel view helps to promote UBC and benefits both actors and society.

An Experimental and Numerical Study of Tip-Leakage Flows in an Idealized Turbine Tip Gap at High Mach Numbers

Abstract: This paper presents results of a detailed investigation of turbine tip-leakage flows at high Mach numbers. The experimental work was carried out using a small blow-down wind tunnel. An idealized blade test section was used to study blade tip-clearance effects in transonic conditions. Unshrouded blade tips are considered and different tip gap heights are investigated. A high blade exit Mach number of Me = 2 was selected deliberately. While conventional transonic turbine stages generally operate at lower supersonic exit Mach numbers, the conditions are representative for ORC turbines. Both experimental and numerical results are presented in this contribution. The results indicate, that tip leakage flow under transonic conditions leads to a complex three-dimensional flow field. A strong interaction between tip gap vortex and trailing edge shocks was observed, that also had a profound effect on the base region. While no final statement on losses could be made in the present configuration, the results indicate a weakened shock system.

Colloidal LaPO4:Gd3+ nanocrystals: X-ray induced single line UV emission.

Abstract: Colloidal solutions of nearly monodisperse 5 nm LaPO4:Gd3+ nanocrystals are shown to strongly emit UV radiation upon excitation with tungsten Kα radiation (59.3 keV) or vacuum UV radiation (160 nm). The UV emission of the particles consists mainly of a single line at 311 nm corresponding to the 6P7/2-8S7/2 transition of Gd3+. The highest emission intensity is observed for LaPO4 nanocrystals with a Gd3+ concentration of 20%. Since the absorption cross section of biomaterials is low for X-rays but high for 311 nm radiation, the UV emission of particles embedded in the biological tissue can only affect the direct vicinity of the particles. Nanocrystals of LaPO4:Gd3+ could, therefore, be interesting for biomedical applications such as strongly localized drug release by X-ray triggered UV uncaging reactions.

CLOWT: A Multifunctional Test Facility for the Investigation of Organic Vapor Flows

Abstract: Organic vapor flows are met in a wide range of technical applications (e.g., energy conversion, chemical processes, and refrigeration). Typically, organic fluids contain complex molecules, and their thermodynamic behavior deviates significantly from the ideal or perfect gas laws. The applicability of scaling laws to organic vapor flows is very limited, and there is a need for detailed experimental investigations under relevant process conditions. Furthermore, such investigations can provide a validation basis for the simulations performed with Computational Fluid Dynamics (CFD) tools. On the other hand, there exists a serious lack in experimental organic vapor flow test facilities. In this contribution, a novel Closed Loop Organic vapor Wind Tunnel (CLOWT) is presented. The concept of CLOWT is based on a closed-loop continuously running wind tunnel cycle. Its main components are a blower, a diffuser, a settling chamber, a contraction zone, a test section module, and a return, including a throttle valve and a mass flow meter. The test facility CLOWT applies the modular design approach which enables analysis of various flow configurations and components like blowers, small axial test turbines, nozzle flows or transonic flows past test objects. Thanks to an auxiliary heating system, organic vapor flows can be investigated at elevated pressure and temperature levels. The operation of CLOWT is based on closed gas turbine cycle control methods (e.g., inventory control). In addition to the general test facility concept, the paper gives a detailed discussion of the CLOWT special design features.