Refine
Year of publication
Document Type
- Conference Proceeding (122)
- Article (41)
- Report (6)
- Book (1)
- Part of a Book (1)
- Working Paper (1)
Keywords
Institute
- Fakultät für Angewandte Informatik (170)
- Institut für Informatik (169)
- Lehrstuhl für vernetzte eingebettete Systeme und Kommunikationssysteme (166)
- Lehrstuhl für Biomedizinische Informatik, Data Mining und Data Analytics (4)
- Empirische Bildungsforschung (1)
- Institut für Geographie (1)
- Lehrstuhl für Innere Medizin mit Schwerpunkt Hämatologie und Onkologie (1)
- Lehrstuhl für Learning Analytics and Educational Data Mining (1)
- Lehrstuhl für Organic Computing (1)
- Mathematisch-Naturwissenschaftlich-Technische Fakultät (1)
The strict restrictions introduced by the COVID-19 lockdowns, which started from March 2020, changed people’s daily lives and habits on many different levels. In this work, we investigate the impact of the lockdown on the communication behavior in the mobile instant messaging application WhatsApp. Our evaluations are based on a large dataset of 2577 private chat histories with 25,378,093 messages from 51,973 users. The analysis of the one-to-one and group conversations confirms that the lockdown severely altered the communication in WhatsApp chats compared to pre-pandemic time ranges. In particular, we observe short-term effects, which caused an increased message frequency in the first lockdown months and a shifted communication activity during the day in March and April 2020. Moreover, we also see long-term effects of the ongoing pandemic situation until February 2021, which indicate a change of communication behavior towards more regular messaging, as well as a persisting change in activity during the day. The results of our work show that even anonymized chat histories can tell us a lot about people’s behavior and especially behavioral changes during the COVID-19 pandemic and thus are of great relevance for behavioral researchers. Furthermore, looking at the pandemic from an Internet provider perspective, these insights can be used during the next pandemic, or if the current COVID-19 situation worsens, to adapt communication networks to the changed usage behavior early on and thus avoid network congestion.
To deliver the best user experience (UX), the human-centered design cycle (HCDC) serves as a well-established guideline to application developers. However, it does not yet cover network-specific requirements, which become increasingly crucial, as most applications deliver experience over the Internet. The missing network-centric view is provided by Quality of Experience (QoE), which could team up with UX towards an improved overall experience. By considering QoE aspects during the development process, it can be achieved that applications become network-aware by design. In this paper, the Quality of Experience Centered Design Cycle (QoE-CDC) is proposed, which provides guidelines on how to design applications with respect to network-specific requirements and QoE. Its practical value is showcased for popular application types and validated by outlining the design of a new smartphone application. We show that combining HCDC and QoE-CDC will result in an application design, which reaches a high UX and avoids QoE degradation.
Group-based communication is a highly popular communication paradigm, which is especially prominent in mobile instant messaging (MIM) applications, such as WhatsApp. Chat groups in MIM applications facilitate the sharing of various types of messages (e.g., text, voice, image, video) among a large number of participants. As each message has to be transmitted to every other member of the group, which multiplies the traffic, this has a massive impact on the underlying communication networks. However, most chat groups are private and network operators cannot obtain deep insights into MIM communication via network measurements due to end-to-end encryption. Thus, the generation of traffic is not well understood, given that it depends on sizes of communication groups, speed of communication, and exchanged message types. In this work, we provide a huge data set of 5,956 private WhatsApp chat histories, which contains over 76 million messages from more than 117,000 users. We describe and model the properties of chat groups and users, and the communication within these chat groups, which gives unprecedented insights into private MIM communication. In addition, we conduct exemplary measurements for the most popular message types, which empower the provided models to estimate the traffic over time in a chat group.
Medical oncology
(2008)
Intrusion Detection Systems (IDS) tackle the challenging task of detecting network attacks as fast as possible. As this is getting more complex in modern enterprise networks, Artificial Intelligence (AI) and Machine Learning (ML) have gained substantial popularity in research. However, their adoption into real-world IDS solutions remains poor. Academic research often overlooks the interconnection of users and technical aspects. This leads to less explainable AI/ML models that hinder trust among AI/ML non-experts. Additionally, research often neglects secondary concerns such as usability and privacy. If IDS approaches conflict with current regulations or if administrators cannot deal with attacks more effectively, enterprises will not adopt the IDS in practice. To identify those problems systematically, our literature survey takes a user-centric approach; we examine IDS research from the perspective of stakeholders by applying the concept of personas. Further, we investigate multiple factors limiting the adoption of AI/ML in security and suggest technical, non-technical, and user-related considerations to enhance the adoption in practice. Our key contributions are threefold. (i) We derive personas from realistic enterprise scenarios, (ii) we provide a set of relevant hypotheses in the form of a review template, and (iii), based on our reviews, we derive design guidelines for practical implementations. To the best of our knowledge, this is the first paper that analyzes practical adoption barriers of AI/ML-based intrusion detection solutions concerning appropriateness of data, reproducibility, explainability, practicability, usability, and privacy. Our guidelines may help researchers to holistically evaluate their AI/ML-based IDS approaches to increase practical adoption.
Browser fingerprinting: how to protect machine learning models and data with differential privacy?
(2021)
As modern communication networks grow more and more complex, manually maintaining an overview of deployed soft- and hardware is challenging. Mechanisms such as fingerprinting are utilized to automatically extract information from ongoing network traffic and map this to a specific device or application, e.g., a browser. Active approaches directly interfere with the traffic and impose security risks or are simply infeasible. Therefore, passive approaches are employed, which only monitor traffic but require a well-designed feature set since less information is available. However, even these passive approaches impose privacy risks. Browser identification from encrypted traffic may lead to data leakage, e.g., the browser history of users. We propose a passive browser fingerprinting method based on explainable features and evaluate two privacy protection mechanisms, namely differentially private classifiers and differentially private data generation. With a differentially private Random Decision Forest, we achieve an accuracy of 0.877. If we train a non-private Random Forest on differentially private synthetic data, we reach an accuracy up to 0.887, showing a reasonable trade-off between utility and privacy.
