Arno Wacker

Requirements of Peer-to-Peer-based Massively Multiplayer Online Gaming

Massively multiplayer online games have become increasingly popular. However, their operation is costly, as game servers must be maintained. To reduce these costs, we aim at providing a communication engine to develop massively multiplayer online games based on a peer-to-peer system. In this paper we analyze the requirements of such a system and present an overview of our current work.

A new approach for establishing pairwise keys for securing wireless sensor networks

Wireless sensor networks based on highly resource-constrained devices require symmetric cryptography in order to make them secure. Integral to this is the exchange of unique symmetric keys between two devices. In this paper, we propose a novel decentralized key exchange protocol that guarantees the confidentiality of a key exchange even if an attacker has compromised some of the devices in the network. A central objective of the protocol design was to minimize resource consumption on the individual devices. We evaluate the resource requirements of our protocol in terms of memory requirements, CPU usage and network traffic both through theoretical analysis and through simulations.

A NAT Traversal Mechanism for Peer-To-Peer Networks

In this demo we present our approach for establishing a communication channel between hosts behind a NAT-based router. To do so, we developed a peer-to-peer based variant of the STUN protocol using so-called superpeers. Using this protocol we determine the used NAT types for the hosts and select a suitable NAT traversal technique dynamically.

Prototyping sensor-actuator networks for home automation

Integrating actuators into sensor networks is often considered to be the next logical step in the evolution of wireless sensor networks. However, few practical examples of such sensor and actuator networks have been demonstrated so far. In this paper, we present a prototype system that supports the easy prototyping of such applications in the area of home automation. We demonstrate the utility of this system with a simple light control application built on top of it. We also report first experiences and insights gained with the help of real-world experiments.

Bootstrapping in Peer-to-Peer Systems

Peer-to-Peer systems have become a substantial element in computer networking. Distributing the load and splitting complex tasks are only some reasons why many developers have come to adopt this technology. However, all of them face a severe problem at the very beginning: setting up an overlay network, such that other clients can easily join it. With an empty peer cache common bootstrapping methods require some manually triggered actions for discovering a peer on the overlay. We therefore introduce an approach for an automated bootstrapping based on DDNS. In this paper we give detailed information about our protocol and document its efficiency and scalability.

A key-distribution scheme for wireless home automation networks

Wireless home automation networks are one example of how wireless technologies may soon become part of our daily life, yet security in existing products is woefully inadequate. An important problem in this area is the question of secure key distribution. We present a key-distribution scheme geared towards home automation networks, but also applicable to other networks with related properties. Our approach uses a decentralized scheme that is designed to work on resource-poor devices, allows easy addition and removal of devices and limits the workload on the end user while guaranteeing the secrecy of the exchanged keys even in the presence of subverted nodes.

Solving the Double Transposition Challenge with a Divide-and-Conquer Approach

Abstract The double transposition cipher was considered to be one of the most secure types of manual ciphers. It was extensively used in both World Wars and during the Cold War. In 1999, Otto Leiberich, the former head of the German federal office for information security, suggested that a double transposition challenge be published with specific parameters designed to ensure its security. Such a challenge was published by Klaus Schmeh in 2007. In November 2013, the authors solved the challenge using a ciphertext-only hill climbing attack. They also solved the challenge using a dictionary attack. In this article, they describe both methods, which are based on a “divide-and-conquer” approach. They additionally discuss the impact of their solutions with respect to the general security of the double transposition cipher.

Understanding the Formation of Trust

Ubiquitous computing systems often take the role of a trustee in a trust relationship between users and ubiquitous computing systems. The goal of this chapter is to increase the understanding of the formation of trust in such trust relationships. Instead of using the predominant theoretical foundation of interpersonal trust, we use the theoretical foundation of trust in automation from the HCI discipline. Since we aim at creating insights on the formation of trust and its dimensions, we develop a formative first-order, formative second-order measurement model for trust. To evaluate the impact of the single indicators and dimensions on trust, we conduct a free simulation experiment. Our results show that the dimensions performance, process and purpose have a comparable impact on trust, and that indicators related to user data are especially important. The results complement existing insights, deepening the understanding of the formation of trust in ubiquitous computing systems. (The complete version of this chapter has been presented at the 33rd International Conference on Information Systems 2012 in Orlando, FL, USA, and is also published in the proceedings of the conference as: Sollner, M., A. Hoffmann, H. Hoffmann, A. Wacker, and J.M. Leimeister, Understanding the Formation of Trust in IT Artifacts, in Proceedings of the International Conference on Information Systems (ICIS) 2012: Orlando, Florida, USA.)

Recht auf Vergessen im Internet

ZusammenfassungDer häufig bemühte Ausspruch „Das Internet vergisst nicht“ umschreibt ein bedeutendes — ungelöstes — Problem für einen effektiven Datenschutz im Internet. Wurden personenbezogene Daten unberechtigt erhoben oder werden sie für den Zweck, zu dem sie erhoben worden sind, nicht mehr benötigt, sind sie zu löschen. Die Löschung personenbezogener Daten, wenn sie rechtswidrig gespeichert sind, ist somit eine der wichtigsten technischen Umsetzungsstrategien zur Gewährleistung der datenschutzrechtlichen Grundsätze der Datenvermeidung und -sparsamkeit sowie ergänzend der Zweckbindung und Erforderlichkeit. Wie aber kann dieser Anspruch auf Löschung realisiert werden, wenn die Löschung von Daten im Internet technisch nicht oder nur schwer möglich ist? Worin unterscheidet sich das durch die Datenschutz-Grundverordnung angedachte „Recht auf Vergessenwerden“ von einer Löschung personenbezogener Daten rechtlich und technisch? Gibt es alternative Lösungsansätze, um die dauerhafte Verfügbarkeit personenbezogener Daten im Internet zu unterbinden?

Socio-technical Design of Ubiquitous Computing Systems

By using various data inputs, ubiquitous computing systems detect their current usage context, automatically adapt their services to the users situational needs and interact with other services or resources in their environment on an ad-hoc basis. Designing such self-adaptive, context-aware knowledge processing systems is, in itself, a formidable challenge. This book presents core findings from the VENUS project at the Interdisciplinary Research Center for Information System Design (ITeG) at Kassel University, where researchers from different fields, such as computer science, information systems, human-computer interaction and law, together seek to find general principles and guidelines for the design of socially aware ubiquitous computing systems. To this end, system usability, user trust in the technology and adherence to privacy laws and regulations were treated as particularly important criteria in the context of socio-technical system design. During the project, a comprehensive blueprint for systematic, interdisciplinary software development was developed, covering the particular functional and non-functional design aspects of ubiquitous computing at the interface between technology and human beings. The organization of the book reflects the structure of the VENUS work program. After an introductory part I, part II provides the groundwork for VENUS by presenting foundational results from all four disciplines involved. Subsequently, part III focuses on methodological research funneling the development activities into a common framework. Part IV then covers the design of the demonstrators that were built in order to develop and evaluate the VENUS method. Finally, part V is dedicated to the evaluation phase to assess the user acceptance of the new approach and applications. The presented findings are especially important for researchers in computer science, information systems, and human-computer interaction, but also for everyone working on the acceptance of new technologies in society in general.