Archiv der Ankündigungen

Florian Jacob, a member of our research group, was a guest on the latest episode of the Matrix Salon podcast, where he talked about his research on the security and resilience of the Matrix network and his life as a Ph.D. student.

Wir veranstalten 2025-03-17 und 2025-03-18 den ROBUST 2025 workshop.

The results of the BMWK-supported project SofDCar (Software-Defined Car) were presented to the public today at a technical expo in the Arena2036 in Stuttgart. Oliver Stengele was there and presented the project contributions of the research group to interested visitors. Within SofDCar, we examined the use of decentralized systems like Ethereum and the InterPlanetary File System to make the cooperation of parties along software supply chains more traceable and secure.

To support us in our daily lives, future humanoid assistant robots need both a certain degree of autonomy to learn and explore, but must also adhere to certain constraints. Constrained planning is a problem especially for otherwise promising approaches based on neural networks - while symbolic approaches are very good at adhering to constraints, but have trouble with complex, new environments. New developments in the area of neuro-symbolic AI would revolutionize constrained task planning. On this year's Symposium on Access Control Models and Technologies, we have presented our BlueSky publication “How to Raise a Robot - A Case for Neuro-Symbolic AI in Constrained Task Planning for Humanoid Assistive Robots” on that topic. The publication is freely available as open access under CC-BY.

At the Bitcoin Research Day in Fall 2024 in New York, Prof. Dr. Hannes Hartenstein and Matthias Grundmann will give a talk about our research. The talk is titled "From Monitoring Bitcoin to Verifying Lightning: Modeling Aspects of the Bitcoin Universe". Find more information at brd.chaincode.com.

At the 37th International Symposium on Distributed Computing (DISC'23), October 9-13, 2023, in L'Aquila, Italy, we presented our work Let It TEE. We showed that the consensus algorithm DAG-Rider can be transformed using Trusted Execution Environments, such as Intel SGX, such that up to 49% of protocol participants can be malicious while progress can still be made.

Today, our staff member Oliver Stengele successfully defended his dissertation. For his work titled "Decentralizing Software Identity Management", Oliver researched approaches that enable developers to sovereignly establish and manage unique identities for software. Additionally, he implemented a digital time capsule on the Ethereum blockchain and employed it as part of an independent review process. We congratulate our colleague!

The research group presented itself at "Meet the Chairs" as part of the Master O-Phase, organized by the Fachschaft Mathematik/Informatik, with a Poster, our Bitcoin Monitoring, and candy. We are grateful for the good organization and the stimulating conversations and look forward to next time.

The research group Decentralized Systems and Network Services is looking for a new research associate with a focus on the design and investigation of identity and access management methods as well as secure and privacy-compliant communication and data storage. Special attention is given to specification, implementation and evaluation of methods for networked and decentralized systems, in particular the Internet of Things, and associated middleware components. Her/his work is part of a larger research project and offers the opportunity for a PhD. For more information and how to contact us, please visit the Human Resources page.

Payment Channels enable scalable payments on blockchains but require that users are regularly online to defend their channels against fraud. This task can be outsourced to third parties, so called watchtowers. At the DINPS'22 workshop, we presented an idea to decentralize watchtowers so that users do not need to trust specific employed watchtowers but a user can be defended by any watchtower.

The research group Decentralized Systems and Network Services is looking for a new academic staff member with a research focus on the design and investigation of identity and access management methods as well as secure and privacy-compliant communication and data storage. Special attention is given to specification, implementation, and evaluation of methods for networked and distributed systems, in particular the Internet of Things, and associated middleware components. Her work is part of a larger research project. Further information and contact details can be found on the Human Resources page.

We presented a short paper about insights into the Bitcoin P2P network at the IEEE International Conference on Blockchain and Cryptocurrency in May 2022. We show for example that the current connection capacity of a majority of the peers is fully used. Matthias Grundmann also presented a poster in which we show how security properties of payment channel protocols can be verified.

At the 3rd IEEE International Conference on Blockchain Computing and Applications (BCCA 2021) in November, Oliver Stengele presented the paper "ETHTID: Deployable Threshold Information Disclosure on Ethereum", which is now available in IEEE Xplore. The paper is the result of a cooperation with the Cryptography and Security Group of Prof. Müller-Quade and was available as a preprint since June. In this work, we show that independently generated statements can be published to a blockchain in a temporally coordinated way through a decentralized mechanism.

At the 3rd Conference on Blockchain Research & Applications for Innovative Networks and Services, Oliver Stengele (Research Group DSN) and Sebastian Friebe (Research Group Telematics) presented a Case Study on coupling Smart Contract applications which resulted from a cooperation within KASTEL.

The research group Decentralized Systems and Network Services in cooperation with the KASTEL Mobility Lab is looking for three student assistants to build up a team for server administration, software development and experiment execution. Further information can be found here.

In the coming summer term, we once again offer our Hot Topics seminar with mixed topics around decentralized systems (registration via Wiwi-Portal). We are also involved with the "Internet and Society" seminar (registration via Wiwi-Portal). Both seminars allow presentation and seminar paper in English.

In the Open Access journal IEEE Access, our article Analysis of the Matrix Event Graph Replicated Data Type was published. With the aim of application in decentralized publish-subscribe systems, in the paper, we extract and analyze the Matrix Event Graph(MEG) from the Matrix middleware, which is primarily used there to depict the causal history of chat messages. We show that the MEG is a so-called Conflict-Free Replicated Data Type, and thereby provides Strong Eventual Consistency. In addition, we show that the MEG, via its reduced notion of consistency when compared to traditional Distributed Ledger Technologies, can cope with environments where the majority of the participants exhibit byzantine faults. We close the article with an analysis of the scalability in form of the number of parallel causal chains in the MEG, for which we can expect an almost optimal evolution according to our results.

At Virtual Zeek Week 2020, we presented the Emojifier and the current state of our work on the Packet Analyzer Framework for Zeek. The framework enables the flexible addition of protocols at lower network layers and thus opens up new possibilities for monitoring networked systems, for example in the context of critical infrastructures.

We present our publication Fundamental Properties of the Layer Below a Payment Channel Network (Abstract-Video) at the 4th International Workshop on Cryptocurrencies and Blockchain Technology (CBT 2020). We show which properties are required for the first layer below a payment channel network and that a first layer cannot only be implemented by a blockchain.

Die Nachklausur wird am 27.07. um 8:00 Uhr im Tulla-Hörsaal (Geb 11.40) stattfinden.

Die Anmeldung im CAS ist ab jetzt bis zum 20.07., 23:59 Uhr möglich. Eine Abmeldung ist bis zum 26.07. um 23:59 Uhr möglich.

Für die Klausur sind keine Hilfsmittel (außer einem Wörterbuch) zugelassen. Sollten Sie ein Wörterbuch verwenden wollen, muss dieses beim Einlass von der Aufsicht überprüft werden.

Weitere Informationen zur Koordinierung des Einlasses und zur Beachtung des Infektionsschutzes werden rechtzeitig vor der Klausur an die Teilnehmer/-innen übermittelt.

At the 25th ACM Symposium on Access Control Models and Technologies, we presented our paper Matrix Decomposition: Analysis of an Access Control Approach on Transaction-based DAGs without Finality. In this paper, we decompose, abstract and analyze the access control approach of the Matrix middleware for decentralized applications, and show that Matrix can be seen as a Distributed Ledger Technology without strict Consensus. This has interesting consequences when compared to traditional access control approaches, which we discuss as well.

The talk was recorded, and will be publishde by SACMAT at a later date. The publication was also the topic of this blog post on Matrix.org, which covers the Matrix.org view on our findings.

The Zeek package contest honors extensions for the well-known network monitoring tool Zeek. In the Zeek Package Contest 2019, two extensions developed in the research group were recognized. The Emojifier won the category for Zeek 3.0 compatible extensions and the Intel-Limiter was awarded the second place in the main competition.

Prof. Hannes Hartenstein will give a presentation at Hochschule Karlsruhe on the 24th of March 2020 at 5:30 PM with the title "Geglückte Verkettung von Zuständen: Blockchains Verstehen" (in German). In this lecture, the basic elements of blockchains will be explained in a generally understandable way and insights into the communication behavior in the Bitcoin network will be presented. Then, existing challenges and approaches to solutions, especially with regard to security and scalability, as well as the automatic execution of contracts on blockchains ("Smart Contracts") are considered. The lecture concludes with a socio-technical view on questions of power in blockchain-based systems. Further Informations at VDE Mittelbaden.

Due to a collision with "Maschinelles Lernen 1", the written exam in "Angewandte Themen für das Informatik-Lehramt" is now on 13 March 2020 at 11:30PM, Bldg. 50.34, Room -101.

At the 3rd International Workshop on Cryptocurrencies and Blockchain Technology (CBT'19) on 26th and 27th Septembre, 2019, co-located with ESORICS 2019 we presented our work "TEE-Based Distributed Watchtowers for Fraud Protection in the Lightning Network". We propose TEE Guard, a distributed watchtower solution for the Lightning Network that utilises Trusted Execution Environments.

The SICK-Wissenschaftspreis for the best thesis 2017 was awarded to Matthias Grundmann for his master thesis titled "Analysis and Evaluation of Analysis Methods for Topology Inference in the Bitcoin Peer-to-Peer Network" at the annual Tag der Informatik. In this thesis he discussed possibilities for dertermining the topology of the Bitcoin peer-to-peer network and introduced two new methods to accomplish this.

On the IEEE International Conference on Blockchain and Cryptocurrency from 14-17 May 2019 in Seoul, South Korea we presented our publication "Banklaves: Concept for a Trustworthy Decentralized Payment Service for Bitcoin", which explores a new way to implement a second layer architecture for cryptocurrencies using Trusted Execution Environments.

Registration to the ACS Practical Course as well as the Seminar "Hot Topics in Decentralized Systems" will open on the 1st of April at 2:00pm via the Wiwi-Portal. Further information can be found on the pages of the respective course.

Edit: Registration for the Seminar was moved to Friday, 5th of April at 10:00am.

Ben Parson, Developer Advocate for Matrix.org, mentioned the DSN Traveller, which was developed in the group as part of the master's thesis of Florian Jacob, in his favourite Matrix projects 2018.

On November 30th Till Neudecker successfully defended his dissertation. Congratulations!

We contributed two articles to the latest KASTEL-Newsletter (in German). In the column "Insights into our Research" (p. 19) we give, as the name implies, a generally comprehensible overview of one of our latest publications, and in the news section (p. 22) we report on the recent Bro Workshop Europe.

Our workshop submission Atomic Information Disclosure of Off-Chained Computations Using Threshold Encryption has been published in the Lecture Notes in Computer Science.

Our group hosts the first European Bro Workshop in September of this year. Bro is an open source network monitoring software project. Read more.

On April 19th and 20th, 2018 the PET-CON 2018.1 took place in Berlin. The workshop was organized by the special interest group Privacy Enhancing Technologies of the Gesellschaft für Informatik. From the DSN group our staff members Marc Leinweber and Matthias Grundmann participated in the workshop.

Am 6. und 7. September findet in Barcelona im Anschluss an die ESORICS 2018 der Internationale Workshop Cryptocurrencies and Blockchain Technologies unter Mitwirkung von Prof. Hartenstein statt.

The second exam for IT-Security Management takes place on Wednesday, 2018/08/01, at 10:30 AM in the Redtenbacher-Lecture Hall. Further details concerning (de-)registration will follow in time.