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See detailFrom Smart to Secure Contracts: Automated Security Assessment and Improvement of Ethereum Smart Contracts
Ferreira Torres, Christof UL

Doctoral thesis (2022)

Modern blockchains, such as Ethereum, gained tremendously in popularity over the past few years. What partially enables this large increase are so-called smart contracts. These are programs that are ... [more ▼]

Modern blockchains, such as Ethereum, gained tremendously in popularity over the past few years. What partially enables this large increase are so-called smart contracts. These are programs that are deployed and executed across the blockchain. However, just like traditional programs, smart contracts are subject to programming mistakes. Although, unlike traditional programs their code is publicly available and immutable. Hence, as smart contracts become more popular and carry more value, they become a more interesting target for attackers. In the past few years, several smart contracts have been exploited, resulting in assets worth millions of dollars being stolen. In this dissertation, we explore the security of smart contracts from three different perspectives: vulnerabilities, attacks, and defenses, and demonstrate that, as so often, "smart" does not imply "secure". In the first part of the dissertation, we study the automated detection of vulnerabilities in smart contracts, without requiring prior access to source code. We start by building a symbolic execution framework for detecting integer bugs that leverages taint analysis to reduce false positives. However, as symbolic execution is notorious to produce false positives, we explore hybrid fuzzing as an alternative. As a result, we propose a hybrid fuzzer for smart contracts that combines symbolic execution with fuzz testing and leverages data dependencies across state variables to efficiently generate transaction sequences. Our approach is capable of detecting more vulnerabilities with less false positives. In the second part of the dissertation, we explore various ways to mount attacks against smart contracts. We start by proposing a framework to detect and quantify classical smart contract attacks (e.g., reentrancy, integer overflows, etc.) on past transactions by combining logic-driven and graph-driven analysis. Afterwards, we study the effectiveness of a new type of fraud known as honeypots, by scanning the entire blockchain for different types of honeypots using symbolic execution. Next, we present a methodology to measure the prevalence of so-called frontrunning attacks, which follow from the rise of decentralized finance and the sharp increase of users trading on decentralized exchanges. Our results show that attackers are making a fortune by manipulating the order of transactions. In the third and final part of the dissertation, we discuss several defense mechanisms for smart contracts. We first propose a solution that developers can use to automatically patch vulnerable smart contract bytecode using context-sensitive patches that dynamically adapt to the bytecode that is being patched. However, this does not solve the issue of already deployed smart contracts. To that end, we present a second solution that enables security experts to write attack patterns that are triggered whenever malicious control and data flows are detected. Once a transaction is detected to be malicious, all state changes are rolled back and the attack is thereby prevented. These attack patterns are written using a domain-specific language and are managed via a smart contract. The latter enables decentralization, guarantees the distribution of security updates, and warrants transparency. [less ▲]

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See detailStatus and Enforceability of EU International Agreements within the Domestic Legal Systems of the Member States: Kupferberg
Neframi, Eleftheria UL

in Wessel, Ramses; Butler, Graham (Eds.) EU External Relations Law: The Cases in Context (2022)

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See detailThe Never‐Ending Road Towards the CEAS: Utopia, Teleology, and Depoliticisation in EU Asylum Policies
Vianelli, Lorenzo UL

in Social Inclusion (2022), 10(3),

This article explores the temporal dimension of the Common European Asylum System (CEAS) by exposing its teleological character and the effects of the latter on the governance of asylum in the European ... [more ▼]

This article explores the temporal dimension of the Common European Asylum System (CEAS) by exposing its teleological character and the effects of the latter on the governance of asylum in the European Union. Drawing on EU policy documents, the article shows how the CEAS has been presented since its inception as a teleology, that is, a process that is inexorably unfolding towards a specific outcome to be reached in an indefinite time in the future. The outcome consists in the establishment of a common area of protection constituted by a level playing field in which asylum seekers and beneficiaries of international protection will be treated alike regardless of the place of residence. Such a teleological narrative informing the CEAS paves the way to overly optimistic expectations on the possibilities of implementation, which in turn result in an overestimation of the potential of harmonisation. By discussing the limitations of harmonisation in relation to the reception of asylum seekers, this article calls into question the possibility of a homogeneous area of protection where equivalent conditions are offered to all asylum seekers across the EU. Such a homogeneous space is utopian because harmonisation does not aim to eradicate differences but rather to mitigate them, thus tolerating diverse arrangements. The article, therefore, argues that the level playing field projected by the CEAS constitutes a promise that has two key effects: First, it depoliticises the CEAS itself by framing problems as technical issues, requiring technical solutions; second, it paves the way to further EU intervention in this field. [less ▲]

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See detailGeometrie der römischen Mosaiken
Perucca, Antonella UL

Scientific Conference (2022)

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See detailShocks and Time: The Development of the European Financial Assistance Regime
Rehm, Moritz UL

in Journal of Common Market Studies (2022)

This paper analyses the impact of economic crises on the development of European financial assistance. It demonstrates that crisis episodes that have taken place over the last five decades have ... [more ▼]

This paper analyses the impact of economic crises on the development of European financial assistance. It demonstrates that crisis episodes that have taken place over the last five decades have significantly altered the design of European Union emergency support. This paper illustrates how solutions adopted in formative moments–including the 1973 oil shock, the Eurozone crisis, and the Covid-19 pandemic–and their long-term consequences led to the smorgasbord of instruments of the present financial assistance structure. By applying a historical institutionalist approach, combining insights from studies of critical junctures and gradual change, this contribution explains how economic shocks contributed to change in financial assistance, while also highlighting mechanisms that led to the continuation of specific elements of the assistance structure. [less ▲]

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See detailLes centrales nucléaires dans la littérature du Luxembourg
Thiltges, Sébastian UL

in Les Cahiers luxembourgeois (2022), 1

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See detailSmall-angle neutron scattering by spatially inhomogeneous ferromagnets with a nonzero average uniaxial anisotropy
Zaporozhets, V. D.; Oba, Y.; Michels, Andreas UL et al

in Journal of Applied Crystallography (2022), 55

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See detailGeodetic climate research in the Austrian Alps
Ullrich, Christian; Francis, Olivier UL; Tabibi, Sajad UL et al

Scientific Conference (2022)

The Federal Office of Metrology and Surveying (BEV) in Austria is responsible for the geodetic reference system like gravity and height reference frame. Some of these gravity reference stations are ... [more ▼]

The Federal Office of Metrology and Surveying (BEV) in Austria is responsible for the geodetic reference system like gravity and height reference frame. Some of these gravity reference stations are monitored regularly by different geodetic terrestrial techniques. The gravity data on some stations show variations and/or changes in gravity. In this presentation, the alpine geodetic reference stations Obergurgl and Franz-Josefs- Höhe in the Austrian eastern Alps will be presented. Both stations are investigated with different geodetic terrestrial techniques in a cooperation of the University of Luxemburg with BEV. Global warming and associated climate change during the last century and recent decades are among the main reasons for glacier retreat in the Alps. Absolute gravity measurements have been regularly performed in the Austrian Eastern Alps since 1987 in the Ötztal Valley at Obergurgl. In addition, absolute gravity has been regularly observed at Obergurgl from 1987 to 2009 with the absolute gravimeter JILAg6. From 2010, the absolute gravity measurements were continued with the highest accurate absolute gravimeters FG5 from BEV and FG5x from University of Luxemburg. The newest gravity data show again a small increase of gravity. Additionally, a permanent GNSS station was established in 2019 to record information about the assumed vertical uplift at this station. A second alpine research station was established near the Pasterze Glacier at Großglockner Mountain in 2019. The Pasterze Glacier is one of the largest glaciers in the eastern Alps and is in the vicinity of the highest mountain of Austria, the Großglockner. The station is monitored by repeated absolute gravity measurements and is equipped with a permanent GNSS station. In addition, precise leveling measurements were also tied to this station. In this contribution, initial results of the geodetic research like the gravity results, precise leveling and GNSS measurements will be presented. In the future, gravity data will be quantitively compared to ice mass balance information derived from glacier inventories. A Geodetic Global Navigation Satellite System reflectometry (GNSS-R) antenna will also be installed to study glacier-ice change. A third station at an altitude of 3300 m is planned and will be checked for operating absolute gravity measurements there. The geodynamical processes like vertical uplift and postglacial deformation will be investigated together with glacier retreat on these stations. [less ▲]

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See detailHow Efficient are Replay Attacks against Vote Privacy? A Formal Quantitative Analysis
Mestel, David UL; Mueller, Johannes UL; Reisert, Pascal

in 35th IEEE Computer Security Foundations Symposium (2022)

Replay attacks are among the most well-known attacks against vote privacy. Many e-voting systems have been proven vulnerable to replay attacks, including systems like Helios that are used in real ... [more ▼]

Replay attacks are among the most well-known attacks against vote privacy. Many e-voting systems have been proven vulnerable to replay attacks, including systems like Helios that are used in real practical elections. Despite their popularity, it is commonly believed that replay attacks are inefficient but the actual threat that they pose to vote privacy has never been studied formally. Therefore, in this paper, we precisely analyze for the first time how efficient replay attacks really are. We study this question from commonly used and complementary perspectives on vote privacy, showing as an independent contribution that a simple extension of a popular game-based privacy definition corresponds to a strong entropy-based notion. Our results demonstrate that replay attacks can be devastating for a voter's privacy even when an adversary's resources are very limited. We illustrate our formal findings by applying them to a number of real-world elections, showing that a modest number of replays can result in significant privacy loss. Overall, our work reveals that, contrary to a common belief, replay attacks can be very efficient and must therefore be considered a serious threat. [less ▲]

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See detailEnergy Harvesting from Jamming Attacks in Multi-User Massive MIMO Networks
Al-Hraishawi, Hayder UL; Abdullah, Osamah; Chatzinotas, Symeon UL et al

in IEEE Transactions on Green Communications and Networking (2022)

5G communication systems enable new functions and major performance improvements but at the cost of tougher energy requirements on mobile devices. One of the effective ways to address this issue along ... [more ▼]

5G communication systems enable new functions and major performance improvements but at the cost of tougher energy requirements on mobile devices. One of the effective ways to address this issue along with alleviating the environmental effects associated with the inevitable large increase in energy usage is the energy-neutral systems, which operate with the energy harvested from radio-frequency (RF) transmissions. In this direction, this paper investigates the notion of harvesting the ambient RF signals from an unusual source. Specifically, the performance of an RF energy harvesting scheme for multi-user massive multiple-input multiple-output (MIMO) is investigated in the presence of multiple active jammers. The key idea is to exploit the jamming transmissions as an energy source to be harvested at the legitimate users. To this end, the achievable uplink sum rate expressions are derived in closed-form for two different antenna configurations. Two optimal time-switching schemes are also proposed based on maximum sum rate and user-fairness criteria. Besides, the essential trade-off between the harvested energy and achievable sum rate are quantified in closed-form. Our analysis reveals that the massive MIMO systems can exploit the surrounding RF signals of the jamming attacks for boosting the amount of harvested energy at the served users. Finally, numerical results illustrate the effectiveness of the derived closed-form expressions through simulations. [less ▲]

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See detailA Framework of Hyper-Heuristics based on Q-Learning
Duflo, Gabriel UL; Danoy, Grégoire UL; Talbi, El-Ghazali UL et al

in International Conference in Optimization and Learning (OLA2022) (2022)

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See detailMORL/D: Multi-Objective Reinforcement Learning based on Decomposition
Felten, Florian UL; Talbi, El-Ghazali UL; Danoy, Grégoire UL

in International Conference in Optimization and Learning (OLA2022) (2022)

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See detailBeware of Greeks bearing entanglement? Quantum covert channels, information flow and non-local games
Mestel, David UL

in 35th IEEE Computer Security Foundations Symposium (2022)

Can quantum entanglement increase the capacity of (classical) covert channels? To one familiar with Holevo's Theorem it is tempting to think that the answer is obviously no. However, in this work we show ... [more ▼]

Can quantum entanglement increase the capacity of (classical) covert channels? To one familiar with Holevo's Theorem it is tempting to think that the answer is obviously no. However, in this work we show: quantum entanglement can in fact increase the capacity of a classical covert channel, in the presence of an active adversary; on the other hand, a zero-capacity channel is not improved by entanglement, so entanglement cannot create `purely quantum' covert channels; the problem of determining the capacity of a given channel in the presence of entanglement is undecidable; but there is an algorithm to bound the entangled capacity of a channel from above, adapted from the semi-definite hierarchy from the theory of non-local games, whose close connection to channel capacity is at the core of all of our results. [less ▲]

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See detailHow additive manufacturing drives business model change: The perspective of logistics service providers
Friedrich, Anne UL; Lange, Anne UL; Elbert, Ralf

in International Journal of Production Economics (2022)

Additive manufacturing (AM) is expected to facilitate local manufacturing in shorter, less complex supply chains and, thus, impact the demand for traditional logistics services. With increasing ... [more ▼]

Additive manufacturing (AM) is expected to facilitate local manufacturing in shorter, less complex supply chains and, thus, impact the demand for traditional logistics services. With increasing dissemination, AM confronts logistics service providers (LSPs) with the question of how they should adapt their business model to the threats and opportunities that come with the emerging digital technologies. We structure the AM activities of LSPs and develop a deep understanding of their resulting business model dynamics. For this exploratory purpose, this study develops a taxonomy and performs a cluster analysis to present six clusters of how LSPs approach AM today. The six profiles include LSPs that reactively monitor AM or, in contrast, proactively leverage AM for their internal operations and the development of new services for their external customers. Among them, four profiles entail fundamental changes to the traditional business models of LSPs. We find that these LSPs oftentimes continue to rely on their traditional “analog” service strengths to offer integrated service bundles of AM and logistics solutions. They bridge their lack of specific resources by strategic alliances with AM experts. Only a few LSPs have started severing ties to their traditional businesses to develop digitally dominated, platform-based AM services that require different resources. Overall, the comprehensive picture of AM activities enables us to contribute to the knowledge of how LSPs navigate in the digital age and to the nexus of business model dynamics and emerging technologies. We propose a set of propositions and support practitioners in analyzing and designing AM activities. [less ▲]

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See detailTechnostress During COVID-19: Action Regulation Hindrances and the Mediating Role of Basic Human Needs among Psychology Students
Schauffel, Nathalie; Kaufmann, Lena Maria UL; Rynek, Mona et al

in Psychology Learning and Teaching (2022)

The COVID-19 pandemic led to an abrupt change from in-person to online teaching in higher education, resulting in increased use of information and communication technology (ICT) and students’ stress and ... [more ▼]

The COVID-19 pandemic led to an abrupt change from in-person to online teaching in higher education, resulting in increased use of information and communication technology (ICT) and students’ stress and uncertainty. Integrating theories of human motivation, stress, and humane work design, we investigated whether different types of action regulation hindrances (ARH) pertaining to human (ICT competence deficits), technology (technical problems), interaction (coordination difficulties), and task aspects (work overload) related to technostress (H1). Furthermore, we examined if this relationship was mediated by satisfaction of the basic human needs for competence, autonomy, and relatedness (H2). Our analysis of causes and mechanisms of technostress is based on cross-sectional survey data (self-report) from 205 psychology students attending an organizational psychology class that was switched from an in-person to an online format due to the COVID-19 pandemic. Structural equation modeling revealed that different types of ARH (i.e., ICT competence deficits, technical problems, coordination difficulties, work overload) positively predicted technostress (β  =  .17 to β  =  .42, p <.05). The effects were (partially) mediated by satisfaction of the need for autonomy (β  =  .11 to β  =  .15, p <.05), for all ARH except technical problems (β  =  .01, p  =  .86). We discuss implications for online course planning, technostress prevention as well as potential interventions beyond pandemic times. [less ▲]

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See detailPerformance Evaluation of Forward Link Packet Scheduling in Satellite Communication Systems with Carrier Aggregation
Al-Hraishawi, Hayder UL; Lagunas, Eva UL; Kumar, Sumit UL et al

Scientific Conference (2022)

The rapidly growing demand for increased data rates and spectrum scarcity in satellite communication systems require new paradigms to effectively utilize radio resources. Of many candidate techniques ... [more ▼]

The rapidly growing demand for increased data rates and spectrum scarcity in satellite communication systems require new paradigms to effectively utilize radio resources. Of many candidate techniques, carrier aggregation (CA) is a promising solution that combines multiple carriers across the available spectrum to achieve a substantial increase in peak data rate and improve user experience. The concept of CA was introduced in 3GPP standards for the terrestrial communication systems and has been successfully deployed and commercialized worldwide. Recently, satellite communication community has investigated the requirements for adopting CA technique to satellite infrastructures. In this setting, aggregating multiple heterogeneous satellite links to boost a single-user peak throughput requires an efficient data packet scheduler at the gateway in order to avoid the out-of-order packet issues and the subsequent queuing delays at the receiver side. Thereby, several research efforts have been devoted to circumvent this challenge through developing packet schedulers that are aiming at delivering data packets without perturbing their original transmission order. In this paper, the performance of the developed schedulers is evaluated using end-to-end system simulations to investigate the impact of different network metrics. The obtained results demonstrate the design tradeoffs and summarize the pros and cons of the schedulers. [less ▲]

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See detailProportionalitätsrechner für Menschen mit einer Dyskalkulie
Perucca, Antonella UL; Ronk, Pit Ferdy UL

Scientific Conference (2022)

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See detailDistraction from Pain in Aging – the Impact of Acute Stress
Dierolf, Angelika UL; van der Meulen, Marian UL; Schulz, André UL et al

in Heinrichs, Markus; Schönauer, Monika (Eds.) 47. Jahrestagung Psychologie und Gehirn (2022)

While older people report acute and chronic pain more often than younger people, and, therefore, would benefit significantly from non-pharmacological pain treatment, little is known about how age affects ... [more ▼]

While older people report acute and chronic pain more often than younger people, and, therefore, would benefit significantly from non-pharmacological pain treatment, little is known about how age affects psychological strategies of pain modulation. Distraction from pain by cognitive engagement, an efficient pain modulation strategy, relies on the prefrontal cortex (PFC). The PFC, however, is an area affected by age-related cognitive decline, which might lead to reduced pain relief through distraction in older adults. Acute stress, a common concomitant phenomenon of pain, might additionally reduce the pain relief effect by its negative impact on PFC and PFC-based executive functions. Healthy young (18-30 years) and older participants (65+ years) performed a pain distraction task before and after acute stress induction using the Trier Social Stress Test, or a respective control condition. An n-Back working memory task with low and high cognitive load served as the distraction paradigm, during which participants received non-painful and moderately painful stimuli. These stimuli were individually adjusted transdermal electrical pulse trains to the inner forearm and participants rated them regarding their intensity and unpleasantness. Pain-related evoked potentials were recorded with a 64-channel EEG, and several saliva samples were collected to measure hormonal stress responses. First analyses on the currently small sample suggest a negative impact of acute stress on distraction from pain in both age groups. Our final results will contribute to a deeper understanding on the efficacy of pain modulation in aging and potential influencing factors, helping to optimize pain treatments in this population. [less ▲]

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See detailGuest Editor, Journal of Risk and Financial Management
Wolff, Christian UL

Diverse speeches and writings (2022)

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