Abstract Many modern systems are built on top of large-scale networks like the Internet. This article provides an overview of a dissertation [29] that addresses the complexity of classic graph problems like the vertex coloring problem in such networks. It has been known for a long time that randomization helps significantly in solving many of these problems, whereas the best known deterministic algorithms have been exponentially slower. In the first part of the dissertation we use a complexity theoretic approach to show that several problems are complete in the following sense: An efficient deterministic algorithm for any complete problem would imply an efficient algorithm for all problems that can be solved efficiently with a randomized algorithm. Among the complete problems is a rudimentary looking graph coloring problem that can be solved by a randomized algorithm without any communication. In further parts of the dissertation we develop efficient distributed algorithms for several problems where the most important problems are distributed versions of integer linear programs, the vertex coloring problem and the edge coloring problem. We also prove a lower bound on the runtime of any deterministic algorithm that solves the vertex coloring problem in a weak variant of the standard model of the area.

Abstract Digital health interventions (DHIs) have the potential to help the growing number of chronic disease patients better manage their everyday lives. However, guidelines for the systematic development of DHIs are still scarce. The current work has, therefore, the objective to propose a framework for the design and evaluation of DHIs (DEDHI). The DEDHI framework is meant to support both researchers and practitioners alike from early conceptual DHI models to large-scale implementations of DHIs in the healthcare market.

Abstract Today, medical data such as diagnoses, procedures, imaging reports and laboratory tests, are not only collected in context of primary research and clinical studies. In addition, citizens are tracking their daily steps, food intake, sport exercises, and disease symptoms via mobile phones and wearable devices. In this context, the topic of “data donation” is drawing increased attention in science, politics, ethics and practice. This paper provides insights into the status quo of personal data donation in Germany and from a global perspective. As this topic requires a consideration of several perspectives, potential benefits and related, multifaceted challenges for citizens, patients and researchers are discussed. This includes aspects such as data quality & accessibility, privacy and ethical considerations.

Abstract A persistent problem for modern Multi-Processors System-on-Chip (MPSoCs) is their vulnerability to code injection attacks. By tampering the memory content, attackers are able to extract secrets from the MPSoC and to modify or deny the MPSoC’s operation. This work proposes SEPUFSoC (Secure PUF-based SoC), a novel flexible, secure, and fast architecture able to be integrated into any MPSoC. SEPUFSoC prevents execution of unauthorized code as well as data manipulation by ensuring memory integrity and authentication. SEPUFSoC achieves: i) efficiency, through the integration of a fast and lightweight hash function for Message Authentication Code (MAC) generation and integrity verification of the memory lines at runtime; and ii) lightweight security, through the use of a Physical Unclonable Function (PUF) to securely generate and store the cryptographic keys that are used for the application authentication. We discuss the security and performance of SEPUFSoC for single core and multi-core systems. Results show that the SEPUFSoC is a secure, fast, and low overhead solution for MPSoCs. We discuss the SEPUFSoC security and cost, which strongly depends on the PUF and hash selection. In the future, new technologies may allow the exploration of different PUFs.

Abstract Currently, timestamps are certified by central timestamping authorities, which have disadvantages of centralization. The concept of the decentralized trusted timestamping (DTT) was developed by Gipp et al. to address these drawbacks. The paper provides insights into the architecture and implementation of a decentralized timestamp service taking the integration of multiple blockchain types into account. Furthermore, the components are introduced and the versatile application scenarios are presented. A future direction of research is the evaluation of blockchain technology and their suitability for timestamping.

Abstract In this article, we propose an architecture that allows to exchange messages or data via a blockchain solution, while keeping the business process independent from the concrete blockchain. The project is the consequence of a need to have fast development of a blockchain based proof of concept that shows the feasibility of a business process, while knowing that in a future step the underlying blockchain solution has to be replaced for reasons of licensing or maximal data throughput. This is done by providing an architecture on base of layers, similar to the OSI-model, and encapsulates the used blockchain within a wrapper layer that covers all blockchain specific properties and only provides a transparent view on the reading or writing from and to the blockchain. The higher layers re-implement point-to-point communication and introduce confidentiality by the use of encryption techniques. The architecture has been tested and proven by implementing two different blockchain solutions that are shielded by specific wrapper layer implementations. This wrapper layer is responsible for the fragmentation of the sent data and their encapsulation into the concrete blockchain solution. The reconstruction of the data takes care of the data fragments being sent potentially out of order or being incomplete. A payload layer is introduced to provide point-to-point communication and to embed the main message inside a message structure. In collaboration with underlying layer it identifies for which message one is not the addressee and allow the underling layer to stop collecting unnecessary data. A crypto-layer finally provides ways of encrypting messages for one or many recipients. Having fixed layers not only allows to replace the underlying blockchain solution but also to extend or replace the other layers in case new security features or optimized protocols need to embedded. The proposed solution does not allow to use specific features like smart contracts and only provides undeniable tamper-proofed existence of a sent message.

it -Information Technology is a strictly peer-reviewed scientific journal.It is the oldest German journal in the field of information technology.Today, the major aim of it -Information Technology is highlighting issues on ongoing newsworthy areas in information technology and informatics and their application.It aims at presenting the topics with a holistic view.It addresses scientists, graduate students, and experts in industrial research and development.

Abstract Abandoning fossil and nuclear energy sources in the long run and increasing amount of renewable energies in electricity production causes a more volatile power supply. Depending on external realities, renewable energy production emphasizes the need for measures to guarantee the necessary balance of demand and supply in the electricity system at all times. Energy intensive industry processes theoretically include high Demand Response potentials suitable to tackle this increasing supply volatility. Nevertheless, most companies do not operate their production in a flexible manner due to multiple reasons: among others, the companies lack know-how, technologies and a clear business case to introduce an additional level of flexibility into their production processes, they are concerned about possible impacts on their processes by varying the electricity demand and need assistance in exploiting their flexibility. Aside from fostering knowledge in industry companies, an IT-solution that supports companies to use their processes’ Demand Response potential has become necessary. Its concept must support companies in managing companies’ energy-flexible production processes and monetarize those potentials at flexibility markets. This paper presents a concept, which integrates both companies and energy markets. It enables automated trading of companies’ Demand Response potential on different flexibility markets.

Abstract In domains such as e-commerce, logistics, or healthcare, the conduct of service processes is widely supported by information systems and event data is generated continuously during process execution. Such event data constitutes a valuable source of information to monitor and improve the respective service processes. My research focuses on models and methods to support event-driven analysis of service processes. Specifically, I study how event logs produced by information systems are used to automatically construct models for qualitative and quantitative analysis. Aiming at online assessment and predictive analysis of a process' behaviour, I develop monitoring techniques that utilise streams of event data produced by diverse sources. Architectures that enable efficient handling of event streams are another focal point of my research. In this article, I outline some of the related research questions and highlight my recent results in these areas.

Abstract Citizen science is a growing approach in science and the opportunities of new technologies and learning are considered more and more. We give an overview of the current practice of mobile learning in Germany by conducting an explorative survey among environmental citizen science projects using mobile apps. This study supports the idea that education is relevant in citizen science, and apps affect the learning experience of participants. However, several obstacles were identified that need to be considered, to be able to fully exploit the benefits of mobile learning in citizen science.