@phdthesis{Bidler2019, author = {Bidler, Margarita}, title = {Consumers' Privacy-Related Decision-Making in the Digital Landscape}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-7996}, school = {Universit{\"a}t Passau}, pages = {XV, 169 Seiten}, year = {2019}, abstract = {Nowadays, consumers are often required to disclose private data in various contexts such as while surfing the internet, downloading a mobile application, or engaging in a business relationship with a firm. Privacy-related decision-making research has so far mainly investigated data disclosure as a cognitive risk-benefit trade-off analysis. While this cognitive approach might be appropriate for situations where consumers have the opportunity for cognitive evaluations, there are many situations in the modern landscape where consumers cannot or do not want to engage in cognitive processing. Decision-making under stress or data disclosure to a business network of collaborating firms, for example, constitute challenges to purely cognitive decision-making approaches, calling for an extension of the established paradigm of cognitive privacy-related decision making. This dissertation advocates for the crucial role of affective processing in many modern data disclosure situations, where consumers do not engage in purely cognitive processing due to external hindrances or a lack of personal involvement in the data disclosure situation.}, language = {en} } @phdthesis{Stoffer2019, author = {Stoffer, Torben}, title = {Service Provisions and Business Relationships in the Digital Era - Four Essays in the B2B Context}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-7558}, school = {Universit{\"a}t Passau}, pages = {v, 99 Seiten}, year = {2019}, abstract = {Digitalization has fundamentally changed how services are provided and how service providers and their customers interact with each other in the business-to-business (B2B) context. Against the backdrop of these developments, this thesis considers - in four essays - the changes brought about by both service and sales digitalization. Each essay investigates for one research topic the aspects of existing knowledge regarding non-digital services and/or sales which can be transferred to digital services and sales and which aspects must be adjusted. The aim is to support B2B firms that offer or receive services or plan to do so in the future which cope with the challenges of service and sales digitalization. In doing so, the first and second essay investigate the contingency effect of service digitalization on service characteristics from the provider and customer views, respectively. Both essays aim at explaining service value as an endogenous variable. In the first essay, service modularity and service flexibility are considered as predecessors that help explain service value. The second essay investigates the effect of customer cocreation on service value. Whereas the first and second essay focus on service characteristics, the third and fourth essay focus on business relationships. Both essays explain relational conflict, one important facet of business relationships, as the endogenous variable and consider the perspectives of both providers and customers. The third essay elaborates on the diverging effect of service digitalization on relational conflict from these two perspectives. The fourth essay incorporates both service and sales digitalization and investigates the contingency effects of the two forms of digitalization on the relationship between coercive power use and relational conflict. In conclusion, this thesis provides a more fine-grained view on the construct digitalization by differentiating explicitly between service digitalization and sales digitalization and introduces a new conceptualization of service (see all four essays) and sales digitalization (see the fourth essay) by treating digitalization as a continuum. Furthermore, this thesis investigates the opportunities and challenges brought about by digitalization. In particular, the first and second essays show the opportunities service digitalization creates for providers, who could benefit from service modularity, and customers, who could benefit from the integration of their own resources into service provisions. In addition, the third essay shows that for providers service digitalization has a positive and for customers contrarily a negative effect on relation conflict. The fourth essay shows that sales and service digitalization positively moderate the effect of coercive power use on relational conflict for weaker parties in business relationships (except for weaker providers) but not for stronger parties. In sum, this thesis contributes to a better understanding of the consequences of service and sales digitalization and provides recommendations for companies facing challenges and decisions related to this development.}, language = {en} } @phdthesis{Luzsa2019, author = {Luzsa, Robert}, title = {A Psychological and Empirical Investigation of the Online Echo Chamber Phenomenon}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-7419}, school = {Universit{\"a}t Passau}, pages = {147 Seiten}, year = {2019}, abstract = {In the public debate it is often assumed that communication in so-called "Echo Chambers" - online structures in which like-minded people share mostly messages that confirm their mutual, shared attitudes - can lead to negative outcomes such as increased societal polarization between groups holding opposing beliefs. This thesis aimed to examine this assumption from a psychological perspective and substantiate it empirically. First, based on existing research and psychological theories, a working definition of Echo Chambers was formulated, that highlights two key factors: Selective Exposure to attitudinally congruent messages and communication in homogeneous networks. Then, three studies were conducted to test links between these factors and two individual-level outcomes that are associated to subjects' actual behavior: Their False Consensus, that is, how strongly subjects perceive the public in agreement with their own attitudes, and their Intergroup Bias, which reflects to which degree subjects' identify as members of an in-group that is in conflict with negatively perceived out-groups. The studies employed questionnaire-based, experimental, as well as real-word data driven approaches. Overall, they confirm that exposure to Echo Chamber-like online structures can indeed lead to a more favorably distorted perception of public opinions and to more signs of Intergroup Bias in subjects' communicational style. Thus, the thesis provides first psychologically founded empirical evidence for effects of online Echo Chamber exposure on behavior-related individual-level outcomes. The results can serve as a basis for further research as well as for the discussion of possible strategies to counter negative effects of online Echo Chambers.}, subject = {Falscher Konsensus-Effekt}, language = {en} } @inproceedings{BergerReiserSousaetal.2019, author = {Berger, Christian and Reiser, Hans P. and Sousa, Jo{\~a}o and Bessani, Alysson}, title = {Resilient Wide-Area Byzantine Consensus Using Adaptive Weighted Replication}, series = {38th IEEE International Symposium on Reliable Distributed Systems (SRDS 2019)}, booktitle = {38th IEEE International Symposium on Reliable Distributed Systems (SRDS 2019)}, publisher = {IEEE Xplore}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-7537}, pages = {10 Seiten}, year = {2019}, abstract = {In geo-replicated systems, the heterogeneous latencies of connections between replicas limit the system's ability to achieve fast consensus. State machine replication (SMR) protocols can be refined for their deployment in wide-area networks by using a weighting scheme for active replication that employs additional replicas and assigns higher voting power to faster replicas. Utilizing more variability in quorum formation allows replicas to swifter proceed to subsequent protocol stages, thus decreasing consensus latency. However, if network conditions vary during the system's lifespan or faults occur, the system needs a solution to autonomously adjust to new conditions. We incorporate the idea of self-optimization into geographically distributed, weighted replication by introducing AWARE, an automated and dynamic voting weight tuning and leader positioning scheme. AWARE measures replica-replica latencies and uses a prediction model, thriving to minimize the system's consensus latency. In experiments using different Amazon EC2 regions, AWARE dynamically optimizes consensus latency by self-reliantly finding a fast weight configuration yielding latency gains observed by clients located across the globe.}, language = {en} } @inproceedings{BergerReiser2018, author = {Berger, Christian and Reiser, Hans P.}, title = {Scaling Byzantine Consensus: A Broad Analysis}, series = {SERIAL'18 Proceedings of the 2nd Workshop on Scalable and Resilient Infrastructures for Distributed Ledgers}, booktitle = {SERIAL'18 Proceedings of the 2nd Workshop on Scalable and Resilient Infrastructures for Distributed Ledgers}, publisher = {ACM}, address = {New York, NY, USA}, isbn = {978-1-4503-6110-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-7526}, pages = {6 Seiten}, year = {2018}, abstract = {Blockchains and distributed ledger technology (DLT) that rely on Proof-of-Work (PoW) typically show limited performance. Several recent approaches incorporate Byzantine fault-tolerant (BFT) consensus protocols in their DLT design as Byzantine consensus allows for increased performance and energy efficiency, as well as it offers proven liveness and safety properties. While there has been a broad variety of research on BFT consensus protocols over the last decades, those protocols were originally not intended to scale for a large number of nodes. Thus, the quest for scalable BFT consensus was initiated with the emerging research interest in DLT. In this paper, we first provide a broad analysis of various optimization techniques and approaches used in recent protocols to scale Byzantine consensus for large environments such as BFT blockchain infrastructures. We then present an overview of both efforts and assumptions made by existing protocols and compare their solutions.}, language = {en} } @phdthesis{Lachat2024, author = {Lachat, Paul}, title = {Detecting Inference Attacks Involving Sensor Data}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-14149}, school = {Universit{\"a}t Passau}, pages = {xiii, 141 Seiten}, year = {2024}, abstract = {The collection of personal information by organizations has become increasingly essential for social interactions. Nevertheless, according to the GDPR (General Data Protection Regulation), the organizations have to protect collected data. Access Control (AC) mechanisms are traditionally used to secure information systems against unauthorized access to sensitive data. The increased availability of personal sensor data, thanks to IoT-oriented applications, motivates new services to offer insights about individuals. Consequently, data mining algorithms have been proposed to infer personal insights from collected sensor data. Although they can be used for genuine purposes, attackers can leverage those outcomes, combining them with other type of data, and further breaching individuals' privacy. Thus, bypassing AC mechanisms thanks to such insights is a concrete problem. We propose an inference detection system based on the analysis of queries issued on a sensor database. The knowledge obtained through these queries, and the inference channels corresponding to the use of data mining algorithms on sensor data to infer individual information, are described using Raw sensor data based Inference ChannEl Model (RICE-M). The detection is carried out by RICE-M based inference detection System (RICE-Sy). RICE-Sy considers at the time of the query, the knowledge that a user obtains via a new query and has obtained via his query history, and determines whether this is sufficient to allow that user to operate a channel. Thus, privacy protection systems can take advantage of the inferences detected by RICE-Sy, taking into account individuals' information obtained by the attackers via a database of sensors, to further protect these individuals.}, language = {en} } @phdthesis{Poehls2018, author = {P{\"o}hls, Henrich C.}, title = {Increasing the Legal Probative Value of Cryptographically Private Malleable Signatures}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-5823}, school = {Universit{\"a}t Passau}, pages = {540, LXXVIII Seiten}, year = {2018}, abstract = {Die Arbeit befasst sich mit der Erarbeitung von technischen Vorgaben und deren Umsetzung in kryptographisch sichere Verfahren von datenschutzfreundlichen, veränderbaren digitalen Signaturverfahren (private malleable signature schemes oder MSS) zur Erlangung möglichst hoher rechtlicher Evidenz. Im Recht werden bestimmte kryptographische Algorithmen, Schl{\"u}ssellängen und deren korrekte organisatorische Anwendungen zur Erzeugung elektronisch signierter Dokumente als rechtssicher eingestuft. Dies kann zu einer Beweiserleichterung mithilfe signierter Dokumente f{\"u}hren. So gelten nach Verordnung (EU) Nr. 910/2014 (eIDAS) qualifiziert signierte elektronische Dokumente entweder als Anscheinsbeweis der Echtheit oder ihnen wird gar eine gesetzliche Vermutung der Echtheit zuteil. Gesetzlich anerkannte technische Verfahren, die einen solch erhöhten Beweiswert erreichen, erf{\"u}llen mithilfe von Kryptographie im wesentlichen zwei Eigenschaften: Integritätsschutz (integrity), also die Erkennung der Abwesenheit von unerw{\"u}nschten Änderungen und die Zurechenbarkeit des unveränderten Dokumentes zum Signaturersteller (accountability). Hingegen ist der größte Vorteil veränderbarer digitaler Signaturverfahren (MSS) die „privacy" genannte Eigenschaft: Eine autorisierte Änderung verbirgt den vorherigen Inhalt. Des Weiteren bleibt die Signatur solange valide wie ausschliesslich autorisierte Änderungen vorgenommen werden. Wird diese Eigenschaft kryptographisch nachweislich sicher erf{\"u}llt, so spricht man von einem private malleable signature scheme. In der Arbeit werden zwei verbreitete Formen, die sogenannten redactable signature schemes (RSS) und die sanitizable signature schemes (SSS), eingehend betrachtet. Diese erlauben vielfältige Einsatzmöglichkeiten, zum Beispiel eine autorisierte spätere Veränderung zur Wahrung von Geschäftsgeheimnissen oder zum Datenschutz: Der Unterzeichner delegiert so beispielsweise {\"u}ber ein private redactable signature scheme nur das nachträgliche Schwärzen (redaction). Dies schränkt die Veränderbarkeit auf das Entfernen von Informationen ein, erlaubt aber wirksam die Wahrung des Datenschutzes oder den Schutz von (Geschäfts)geheimnissen indem diese Informationen irreversibel f{\"u}r Angreifer entfernt werden. Die kryptographische privacy Eigenschaft besagt, dass es nun nicht mehr effizient möglich ist, aus dem geschwärzten Dokument Wissen {\"u}ber die geschwärzten Informationen zu erlangen, auch und gerade nicht f{\"u}r den Signaturpr{\"u}fer. Die Arbeit geht im Kern der Frage nach, ob ein MSS sowohl die kryptographische Eigenschaft „privacy" als auch gleichzeitig die Eigenschaften „integrity" und „accountability" mit ausreichend hohen Sicherheitsniveaus erf{\"u}llen kann. Das Ziel ist es, dass ein MSS gleichzeitig ein solch ausreichend hohen Grad an Sicherheit erf{\"u}llt, dass (1) die autorisierten nachträglichen Änderungen zum Schutze von Geschäftsgeheimnissen oder personenbezogenen Daten eingesetzt werden können, und dass (2) dem Dokument, welches mit dem speziellen Signaturverfahren signiert wurde, ein erhöhter Beweiswert beigemessen werden kann. In Bezug auf letzteres stellt die Arbeit sowohl die technischen Vorgaben, welche f{\"u}r qualifizierte elektronische Signaturen (nach Verordnung (EU) Nr. 910/2014) gelten, in Bezug auf die nachträgliche Änderbarkeit dar, als auch konkrete kryptographische Eigenschaften und Verfahren um diese Vorgaben kryptographisch beweisbar zu erreichen. Insbesondere weisen veränderbare Signaturen (MSS) einen anderen Integritätsschutz als traditionelle digitale Signaturen auf: Eine signierte Nachricht darf nachträglich durch eine definierte dritte Partei in einer definierten Art modifiziert werden. Diese sogenannte autorisierte Änderung (authorized modification) kann auch ohne Kenntnis des geheimen Signaturschl{\"u}ssels des Unterzeichners durchgef{\"u}hrt werden. Bei der Verifikation der digitalen Signatur durch den Signaturpr{\"u}fer bleibt der urspr{\"u}ngliche Signierende und dessen Einwilligung zur autorisierten Änderung kryptographisch verifizierbar, auch wenn autorisierte Änderungen vorgenommen wurden. Die Arbeit umfasst folgende Bereiche: 1. Analyse der Rechtsvorgaben zur Ermittlung der rechtlich relevanten technischen Anforderungen hinsichtlich des geforderten Integritätsschutzes (integrity protection) und hinsichtlich des Schutzes von personenbezogenen Daten und (Geschäfts)geheimnissen (privacy protection), 2. Definition eines geeigneten Integritäts-Begriffes zur Beschreibung der Schutzfunktion von existierenden malleable signatures und bereits rechtlich anerkannten Signaturverfahren, 3. Harmonisierung und Analyse der kryptographischen Eigenschaften existierender malleable signature Verfahren in Hinblick auf die rechtlichen Anforderungen, 4. Entwicklung neuer und beweisbar sicherer kryptographischer Verfahren, 5. abschließende Bewertung des rechtlichen Beweiswertes (probative value) und des Datenschutzniveaus anhand der technischen Umsetzung der rechtlichen Anforderungen. Die Arbeit kommt zu dem Ergebnis, dass zunächst einmal jedwede (autorisierte wie auch unautorisierte) Änderung von einem kryptographisch sicheren malleable signature Verfahren (MSS) ebenfalls erkannt werden muss um Konformität mit Verordnung (EU) Nr. 910/2014 (eIDAS) zu erlangen. Eine solche Änderungserkennung durch die der Signaturpr{\"u}fer, ohne Zuhilfe weiterer Parteien oder Geheimnisse, die Abwesenheit von autorisierten und unautorisierten Änderungen erkennt wurde im Rahmen der Arbeit entwickelt (non-interactive public accountability (PUB)). Diese neue kryptographische Eigenschaft wurde veröffentlicht und bereits von Arbeiten Anderer aufgegriffen. Des Weiteren werden neue kryptographische Eigenschaften und redactable signature und sanitizable signature Verfahren vorgestellt, welche zusätzlich zu dieser Änderungerkennung einen starken Schutz gegen die Aufdeckung des Orginals ermöglichen. Werden geeignete Eigenschaften erf{\"u}llt so wird f{\"u}r bestimmte Fälle ein technisches Schutzniveau erzielt, welches mit klassischen Signaturen vergleichbar ist. Damit lässt sich die Kernfrage positiv beantworten: Private MSS können ein Integritätsschutzniveau erreichen, welches dem rechtlich anerkannter digitaler Signaturen technisch entspricht, aber dennoch nachträgliche Änderungen autorisieren kann, welche einen starken Schutz gegen die Wiederherstellung des Orginals ermöglichen.}, subject = {Integrit{\"a}t}, language = {en} } @article{MaletzkydeGarcia2021, author = {Maletzky de Garc{\´i}a, Martina}, title = {Bridging the state and market logics of refugee labour market inclusion - a comparative study on the inclusion activities of German professional chambers}, series = {Comparative Migration Studies}, journal = {Comparative Migration Studies}, doi = {10.1186/s40878-021-00232-6}, url = {http://nbn-resolving.de/urn:nbn:de:101:1-2021100821553693088701}, pages = {20 Seiten}, year = {2021}, abstract = {Due to their high numbers, refugees' labour market inclusion has become an important topic for Germany in recent years. Because of a lack of research on meso-level actors' influences on labour market inclusion and the transcendent role of organizations in modern societies, the article focuses on the German professional chambers' role in the process of refugee inclusion. The study shows that professional chambers are intermediaries between economic actors, the government and refugees, which all follow their own logics and ideas of labour market inclusion (the state, the market and the community logic). The measures taken by professional chambers mainly reflect a governmental logic (to reduce refugee unemployment) combined with a market logic (to provide human resources to economic actors). A community logic (altruism) only comes into play as a rather unintended consequence of measures addressing the other two logics. The measures of two types of professional chambers are compared. Close similarities between them reveal that the organization type is of theoretical relevance to explain the type of measures organizations opt for.}, language = {en} } @article{AnagnostopoulosTeymuriSeratietal.2023, author = {Anagnostopoulos, Nikolaos Athanasios and Teymuri, Benyamin and Serati, Reza and Rasti, Mehdi}, title = {LP-MAB: Improving the Energy Efficiency of LoRaWAN Using a Reinforcement-Learning-Based Adaptive Configuration Algorithm}, series = {Sensors}, volume = {23}, journal = {Sensors}, number = {4}, editor = {Xie, Bin and Wang, Ning and Gu, Yi and Stefanidis, Angelos}, publisher = {MDPI}, address = {Basel, Switzerland}, issn = {1424-8220}, doi = {10.3390/s23042363}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-11853}, pages = {22 Seiten}, year = {2023}, abstract = {In the Internet of Things (IoT), Low-Power Wide-Area Networks (LPWANs) are designed to provide low energy consumption while maintaining a long communications' range for End Devices (EDs). LoRa is a communication protocol that can cover a wide range with low energy consumption. To evaluate the efficiency of the LoRa Wide-Area Network (LoRaWAN), three criteria can be considered, namely, the Packet Delivery Rate (PDR), Energy Consumption (EC), and coverage area. A set of transmission parameters have to be configured to establish a communication link. These parameters can affect the data rate, noise resistance, receiver sensitivity, and EC. The Adaptive Data Rate (ADR) algorithm is a mechanism to configure the transmission parameters of EDs aiming to improve the PDR. Therefore, we introduce a new algorithm using the Multi-Armed Bandit (MAB) technique, to configure the EDs' transmission parameters in a centralized manner on the Network Server (NS) side, while improving the EC, too. The performance of the proposed algorithm, the Low-Power Multi-Armed Bandit (LP-MAB), is evaluated through simulation results and is compared with other approaches in different scenarios. The simulation results indicate that the LP-MAB's EC outperforms other algorithms while maintaining a relatively high PDR in various circumstances.}, language = {en} } @article{HerboldHautli‑JaniszHeueretal., author = {Herbold, Steffen and Hautli‑Janisz, Annette and Heuer, Ute and Kikteva, Zlata and Trautsch, Alexander}, title = {A large‑scale comparison of human‑written versus ChatGPT‑generated essays}, series = {Scientific Reports}, volume = {13}, journal = {Scientific Reports}, publisher = {Springer Nature}, doi = {10.1038/s41598-023-45644-9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus4-13961}, pages = {11 Seiten}, abstract = {ChatGPT and similar generative AI models have attracted hundreds of millions of users and have become part of the public discourse. Many believe that such models will disrupt society and lead to significant changes in the education system and information generation. So far, this belief is based on either colloquial evidence or benchmarks from the owners of the models—both lack scientific rigor. We systematically assess the quality of AI-generated content through a large-scale study comparing human-written versus ChatGPT-generated argumentative student essays. We use essays that were rated by a large number of human experts (teachers). We augment the analysis by considering a set of linguistic characteristics of the generated essays. Our results demonstrate that ChatGPT generates essays that are rated higher regarding quality than human-written essays. The writing style of the AI models exhibits linguistic characteristics that are different from those of the human-written essays. Since the technology is readily available, we believe that educators must act immediately. We must re-invent homework and develop teaching concepts that utilize these AI models in the same way as math utilizes the calculator: teach the general concepts first and then use AI tools to free up time for other learning objectives.}, language = {en} }