Oberseminar Rechnernetze und Telematik (WiSe 2024/2025)

In the oberseminar, talks are held on selected topics, as well as final presentations of master's & bachelor's theses, and projects. The seminar takes place hybridly:

• In room 051-02-008, as well as via
• Zoom - link (Meeting-ID: 879 6692 5056, Kenncode: WR6RriwYD)

Oberseminar Talks:

• 26.03.2025 15:00-15:30 Richard Dutt, Bachelor Project Final Presentation
  
  Title: Security Protocol for Mental Card Games

  Abstract: This project develops a decentralized security protocol for mental card games, addressing six core criteria: confidentiality, integrity, accountability, availability, controlled access and fairness, through cryptography and peer-to-peer consensus. By eliminating central authorities, the protocol replicates the trust and strategic depth of traditional card games in mediated play.

•  26.03.2025 15:30-16:00 Matthias Bundy, Bachelor Thesis Kickoff Presentation

  Title: Modelling of Mutual 3D Hertzian Impedances

  Abstract: The Hertzian Model is of great importance in the field of antenna theory. It describes the behaviour of very small dipoles using some simplifying approximations. It is the standard approach in antenna theory to use the so called impedance matrix, whose entries describe the mutual impedances between two dipoles each. A formula describing the mutual impedance between two dipoles which are perpendicular placed in a plane and parallel oriented was already derived in 2009 by Yordanov et. al. in [1]. We will derive a new, extended formula for arbitrary oriented dipoles.

  
  [1] Yordanov, H., Russer, P., Ivrlac, M. T., & Nossek, J. A. (2009). Arrays of isotropic radiators-a field-theoretic justification. 32-35. Beitrag in International ITG Workshop on Smart Antennas, WSA 2009, Berlin, Deutschland. 

• 19.03.2025 14:00-14:30 Stefan Bräuner, Bachelor Project Kickoff Presentation
  
  Title: Building a peer-to-peer sensor network lab setup

  Abstract: In this project, a sensor network will be set up using microcontrollers to connect these sensor nodes in a peer-to-peer network. Development boards with an ESP32 processor are used to enable a variety of test setups. These boards have integrated wireless and Bluetooth functionality as well as interfaces for programming, various sensors and power supply without the need for additional hardware. The sensors used are Nova Fitness SDS011 Laser Dust Particle Sensors, which measure the concentration of dust particles in the air and therefore the air quality.

  Three identical nodes consisting of a controller and a sensor are built, with the microcontrollers connected via WiFi. Both a solution using Espressif's ESP-NOW protocol and a solution using a WiFi mesh network will be tested.

• 19.03.2025 14:45-15:15 Emre Bayazitoglu Bachelor Thesis Final Presentation
  
  Title: Design, Simulation, and Evaluation of a Load Balancing Algorithm for Peer-to-Peer-Networks based on Push-Pull Sum and Deal-Agreement-Based Algorithms

  Abstract: The Push-Pull Sum algorithm, introduced in [1], combines elements of the Push-Sum [2] and Pull-Sum algorithms. The Push-Sum algorithm, proposed by Kempe et al., is a load balancing method where each node randomly selects a neighbor and transfers half of its current sum and weight to that neighbor. Load balancing algorithms are designed to evenly distribute loads across networks, typically modeled as undirected graphs. In such networks, nodes exchange loads with their neighbors to achieve a balanced state. The Single-Proposal Deal-Agreement-Based load balancing algorithm, as presented in [3], incorporates a deal-agreement mechanism into load transfers in order to achieve fair load transfers between two nodes.

  In this thesis, I propose and implement a variation of the Push-Pull Sum algorithm that integrates principles from the Deal-Agreement-Based algorithm and adaptive thresholding. This adaptation modifies and extends certain properties of the original Push-Pull Sum algorithm. For the Adaptive Threshold Push-Pull Sum algorithm, I provide pseudocode, implement the different load balancing approaches in a peer-to-peer network, and analyze simulation outcomes across different topologies. The objective is to find a compromise solution including overall good performance in different topologies. The performance of this algorithm is evaluated using the mean squared error (MSE) reduction over time as a convergence metric. Results are presented using log-log and log-linear graphs to compare the efficiency of error reduction in various scenarios. The slopes of the MSE curves give insights into how effectively the algorithms distribute loads across the network. Additionally, the data is fitted to different models to assess the rate of convergence per region.
  The findings suggest that the proposed modifications to the Push-Pull Sum algorithm achieve a more efficient and scalable load balancing strategy for most of the scenarios tested in the experiments. The adaptive threshold mechanism added to the Push-Pull Sum algorithm dynamically adjusts the threshold based on the state of imbalance in the network, making it efficient in dense graphs as well as low regular degree graphs. In some of the topologies under test, the Adaptive Threshold Push-Pull Sum algorithm acts as an intermediate solution between the Deal-Agreement-Based and Push-Pull Sum algorithms.
  
  [1]: S. Nugroho, A. Weinmann, and C. Schindelhauer, Adding Pull to Push Sum for Approximate Data Aggregation. Springer, 2023.
  [2]: D. Kempe, A. Dobra, and J. Gehrke, “Gossip-based computation of aggregate information,” in 44th Annual IEEE Symposium on Foundations of Computer Science, 2003. Proceedings., pp. 482–491, 2003.
  [3]: Y. Dinitz, S. Dolev, and M. Kumar, “Local deal-agreement algorithms for load balancing in dynamic general graphs,” Theory of Computing Systems, vol. 67, pp. 348–382, Apr 2023. 

• 19.03.2025 15:30-16:00 Giacomo Mossio Master Thesis progress report

  Title: Progress Report: Ant-Colony Algorithms for Power Grid Creation

  Abstract: This presentation covers the ongoing work on using Ant Colony Optimization (ACO) to generate synthetic Medium Voltage (MV) grids, with an emphasis on enhancing efficiency and scalability.
  The methodology leverages ACO along with real-world data to create valid grid solutions, optimizing their topology while tackling key challenges such as cost minimization, network overloads, and scalability.

  19.03.2025 16:00-16:30 Matthias Bundy Bachelor Project Final Presentation
  
  

  Title: Simulation of Near-Field-Impedance Matrices
  
  Abstract:  

  We discuss the Hertzian dipole model and its simplifications from the real world situation. The Hertzian model, although it is very old, has never completly been analysed, since it is a very common practise only to consider situations where the antennas are far away from each other (in their far-field region) and there is only a small number of antennas present. With the increasing interest in the near-field region of Hertzian dipoles it is important to reason about the correctness of the model. Since previous inaccuracies in the model could always be blamed on the approximations made, the question remains weather this model is correct if we consider all aspects of it. In order to do so, we especially look at lots of antennas in their respective near-field region. We present two strategies trying to provide examples where the Hertzian model fails to describe the behavior of the antennas in a correct way. While there already are examples for the simplifying case of far-field situations, there is (still) no situation found proving the complete Hertzian model inaccurate, especially in the near-field region.
  
  The approaches of proving the Hertzian model inaccurate as well as the results of the simulations will be presented.

• 12.03.2025 14:00-14:30: Henrik Leisdon, Master Thesis final presentation 
  
  vulnerabilities in optical and non-optical gates, revealing attack vectors that can compromise encryption data. To address these, we proposed several counter measures, including improved key generation and encryption method selection.

• 12.03.2025 14:45-15:15: Fateh Aslam , Master Thesis final presentation

  Title: Verbesserung des 2D-Visuellen-Kryptografie-Schemas durch diffuse Reflexion

  Abstract: In dieser Arbeit wird ein innovatives kryptografisches System auf Basis der Interaktion eines Lichtstrahls mit einer zweidimensionalen Umgebung entwickelt. Durch Modifizierung des Reflexionsverhaltens des Lichts wird eine diffuse Reflexion ermöglicht – im Gegensatz zur herkömmlichen spiegelgerichteten Reflexion mit gleichem Einfalls- und Ausfallswinkel.

  Die Umsetzung der diffusen Reflexion beruht auf einer rotationsbasierten Streuung entlang der berechneten Oberflächennormalen. Es ergibt sich eine Menge diffuser Sekundärstrahlen, die nach dem lambertschen Kosinusgesetz gewichtet werden. Abschließend untersucht diese Arbeit die kryptografischen Besonderheiten dieser Reflexionsmethode und deren Einfluss auf die Sicherheit des Systems. Dabei werden verschiedene kritische Angriffsmethoden betrachtet und der Einfluss der diffusen Reflexion im Vergleich zur spiegelgerichteten Reflexion analysiert. Die Ergebnisse unterstreichen eindeutig, dass die Einführung der diffusen Reflexion die Sicherheit des Systems erheblich verbessert und zusätzliche Barrieren für potenzielle Angreifer
  schafft.

• 12.03.2025 15:30-16:00: Lukas Franz, Master Thesis final presentation 
  
  Title:  Relevant Lattice Code Research for Mental Card Game Applications
  
  Abstract: This literature review examines whether advancements in lattice-based cryptography can support the implementation of mental card games. The primary focus lies on finding a primitive that allows operations on ciphertexts encrypted by multiple parties and finding a lattice-based zero knowledge proof of a shuffle. The findings suggest that while the necessary cryptographic primitives are available, no research has yet shown how to integrate them into a fully operational mental card game protocol, increased by the fact that the various components were designed separately and optimized for different applications and might require modifications. Moreover this review provides an extensive overview of potential candidates for constructing such a protocol.
  
  

• 05.03.2025 15:00-15:30: Christian Simeon Maria Armbruster, Bachelor Thesis Final Presentation 
  
  Title:  Proving Matrix Multiplication using Bulletproofs
  
  Abstract: We present an interactive protocol for proving matrix multiplication in logarithmic communication complexity. That means: For a public matrix M and a public vector c as well as private, committed vectors a and b, the prover can demonstrate that M * a = b + c. Our argument is complete, sound and zero-knowledge. The protocol achieves logarithmic communication complexity by using two function calls to the inner product argument of Bulletproofs [BCC+2016; BBB+2018]. It is a modified version of the matrix product argument of Schindelhauer [Sch2024]. 

• 21.02.2025 15:00-15:30 Zoom only: Robin Steiger, Master Thesis Final Presentation 
  
  Title:  Adaptive Local Planning - for Improved Pose Certainty in Active SLAM
  
  Abstract: The thesis presents a novel approach to autonomous navigation in unknown environments by enhancing the DWA Planner within ROS. By leveraging a novel pose certainty estimation, the proposed method dynamically balances goal-directed navigation with real-time pose improvement. Evaluations in both simulated and real-world settings demonstrate promising results in navigation accuracy.
• 19.02.2025 14:00-14:45 Zoom only:  Ludwig Ettner, Seminar presentation
  
  Title: How not to prove your election outcome
  
  Abstract:The paper ‘How not to prove your election outcome’ by Sarah Jamie Lewis analyses vulnerabilities in the SwissPost-Scytl sVote internet system, which allow manipulated deciding evidence to be created, which can be formally verified but provide false results.

  This talk summarises the key messages of the paper and explains the underlying cryptographic methods and their significance for the verifiability of voting systems. The aim is to develop an understanding of the problem and to analyse the implications of such vulnerabilities for the verification of voting systems.

• 29.01.2025 14:00-14:30 Sid Moreira, Bachelor Thesis Final Presentation

  Titel: Entwurf und Analyse eines Selbststabilisierungsmechanismus für Kademlia unter Verwendung von zufälligen Graphtransformationen

  Abstract: In dieser Präsentation werde ich die Entwicklung und Analyse von HybridKad vorstellen, einem selbststabilisierenden Overlay-Netzwerk. Peer-to-Peer-Netzwerke spielen eine zentrale Rolle bei der Entwicklung verteilter Systeme, jedoch zeigen etwa Kademlia-basierte Systeme, Schwächen in hochdynamischen Umgebungen, insbesondere bei Knotenfluktuation (Churn) und adversarialem Verhalten.
  
  Der zentrale Ansatz von HybridKad besteht darin, das Kademlia-Netzwerk durch ein d-reguläres Overlay (R-Netzwerk) zu erweitern, das durch KadFlip- und 1-Flip-Operationen sukzessive zu einem Expander-Graphen konvergiert. Diese Operationen stellen die Stabilität des Netzwerks sicher. Die KadFlip-Operation verschiebt dabei Kanten zwischen den Overlays und verhält sich auf dem Graphen des R-Overlays äquivalent zur Switch-Operation, wodurch starre Topologien und Separating Gadgets überwunden werden.
  
  Die Analyse zeigt, dass ein HybridKad-Graph unter KadFlip-Operationen zu einem Expander-Graphen konvergiert, was durch erste Simulationen gestützt wird. Gleichzeitig nutzt HybridKad eine angepasste k-Bucket-Aktualisierungsstrategie, um den Zusammenhang des Netzwerks zu garantieren und gleichzeitig das Routing über die k-Buckets beizubehalten.
  
  Abschließend werde ich die von Mahlmann und Schindelhauer in [1] zusammengefassten Kriterien für Graphtransformationen im Zusammenhang mit KadFlip diskutieren und zukünftige Forschungspfade aufzeigen.
  
  [1] Peter Mahlmann und Christian Schindelhauer. „Random Graphs for Peer-to-Peer Overlays“. In: The European Integrated Project "Dynamically Evolving, Large Scale Information Systems (DELIS), Proceedings of the Final Workshop 222 (2008), S. 1–22.

• 29.01.2025 15:00-15:30 Shuran Liu, Bachelor Thesis Kickoff Presentation  
  
  Topic: Exploring the Feasibility of Multiplicative Shared Public Key Systems in Cryptography

  Outline:  The shared public key system based on the El-Gamal algorithm plays a vital role in cryptography, providing a foundation for secure communication and multi-party protocols. In traditional methods, the shared public key relies on additive forms of key generation. This research explores the feasibility of a novel multiplicative approach to shared public key creation. The proposed method involves constructing the shared public key as the product of individual public keys, derived from private keys contributed by all participants.
  
  This study evaluates the security, computational efficiency, and practicality of this multiplicative shared public key system, particularly in the context of secure multi-party scenarios such as Mental Card Games. Key metrics include resistance to attacks under the discrete logarithm assumption, computational complexity in generating and using the key, and operational feasibility

• 08.01.2025 14:00-14:30 Peter Gillessen, Bachelor Thesis Kickoff Presentation

  Topic: HTTP/3 Request Smuggling Vulnerabilities: Testing Reverse-Proxies
  in General Graph

  Outline: HTTP/3 is on track to become the primary standard for web app lication communication. While it's increasingly being integrated into modern browsers, there's still much to learn about its security implications. One major concern is Request Smuggling attacks, which pose a significant threat to the security and privacy of web applications. These attacks can lead to serious consequences such as cache poisoning, session hijacking, and DoS attacks. First studies on HTTP/3 Request Smuggling vulnerabilities are currently being carried out by Pisu et al. at the University of Cagliari, among others. This bachelor thesis follows on from the work of Pisu et al. by reviewing and refining their proposed methodology to test reverse-proxies for such vulnerabilities. The enhanced methodology will be applied to popular reverse

• 18.12.2024 14:00-14:30 Yi-Chieh Lin Master Project kickoff 
  
  Topic: Simulation Comparison of Asynchronous Local Deal-Agreement Algorithms in General Graph

  Outline: For the research, we will use the local deal-agreement based algorithm that is proposed by Y. Dinitz et al. [1] in an asynchronous situation to simulate the practical results in various graphs. Asynchronous means that the network is event-based, which states that the transmission of messages are driven by each single event. In the real-world, the simulation of an Asynchronous network can be helpful as it provides the convenience that we do not need to wait for the former one to end, we can keep on doing other operations, solving the restrictions of synchronous ones. Also, the research of Y. Dinitz et al. solve the deadlock problem of a peer being to keep waiting for a message that won’t be backed, by a self-stabilizing load balancing algorithm. It makes sure that every message will be received, and improves the duplications and omissions problem in the original algorithm for asynchronous networks. In this study, we will simulate the self-stabilizing load balancing algorithm in different graphs and analyze the differences and similarities that are presented in the results of the modeling scenarios.

  [1] Dinitz, Y., Dolev, S., & Kumar, M. (2020). Local deal-agreement based monotonic distributed algorithms for load balancing in general graphs. arXiv preprint arXiv:2010.02486.

• 18.12.2024 14:45-15:15 Arthur Mannßhardt, Bachelor Project kickoff 

  Title: Coding of a Domain-Specific Language for Mental Card Games

  Abstract: In our Bachelor Project we develop a Domain-Specific Language(DSL) for Mental Card Game.
  In particular, we try to create a tool to autogenerate code for a given Card game ruleset, which meets the demands for Mental Card Games or at least establishes the groundwork for future other code-related Mental Card game projects.

• 18.12.2024 15:30-16:00 Christian Ambruster Bachelor Thesis Kickoff 
  
  Title: Proving matrix multiplication using bulletproofs

• Abstract: This presentation explores a protocol for proving matrix multiplication using bulletproofs from the lecture Introduction to Cryptography. That is, proving that you know secret vectors a and b, such that M * a = b + c. The protocol uses two function calls to the Inner Product Argument from Bünz et al.: Bulletproofs. Short proofs for confidential transactions and more and uses logarithmic communication complexity. Additionally, the intuition for completeness and soundness of the protocol will be given.

• 11.12.2024 14:00-14:30 Richard Dutt, Bachelor Project, Kickoff
  
  Title:  Defining Security Objectives for Mental Card Games 
  
  Abstract: This presentation explores the importance of security in mental card games (MCGs), with a focus on understanding key objectives, identifying core security terms, and proposing a protocol for testing security in various implementations.
  
  Understanding Security in the Context of MCGs
  1) Why do MCGs require security measures?
  2) Overview of key security objectives like reliability, discretion, and integrity.
  3) Key Security Terms
  4) Brief mention of terms like authentication, sabotage, and proof safe.
  5) Developing a Testing Protocol
  6) Presenting the concept of creating a protocol to test the security of different MCG projects..
  7) Discussion: Security Expectations for MCGs
  8) Engaging the audience to refine priorities for real-life and online scenarios.
  
  

• 11.12.2024 14:30-14:45 Katsiaryna Mironava, Bachelor Thesis, Kickoff
  
  Title: Implementierung und Migration zu sicheren Post-Quanten-Kryptographie-Verfahren in Unternehmensumgebung

  Abstract:
  Ziel dieser Bachelorarbeit ist es, die Implementierung und Migration zu sicheren Post-Quanten-Kryptographie (PQK)-Verfahren in Unternehmensumgebungen zu untersuchen. Zunächst wird ein Hintergrund zum Thema gegeben, gefolgt von einer Analyse der Bedrohungen, die klassische Kryptographie durch Quantencomputing erfahren wird. 
  Im dritten Kapitel werden gitterbasierte Verfahren als eine vielversprechende Lösung im Bereich der PQK vorgestellt. Dies umfasst die mathematischen Grundlagen, Public-Key-Verfahren, Schlüsselaustauschverfahren und digitale Signaturverfahren. Das vierte Kapitel sollte sich mit der Migration zu PQK beschäftigen, einschließlich der Terminologie, Hauptphasen und Rollen innerhalb des Migrationsprozesses. Es werden verschiedene Implementierungsstrategien, wie rein PQK-basierte und hybride Ansätze, beleuchtet sowie die damit verbundenen Herausforderungen diskutiert.
  Abschließend wird die Arbeit die Erkenntnisse zusammenfassen und einen Ausblick auf die zukünftige Entwicklung und Anwendung von PQK in Unternehmensumgebungen geben.

• 11.12.2024 14:45-15:15 Mikado Wilpert, Bachelor Thesis, Kickoff
  
  

  Title: Optimization of Bluetooth Low Energy distance measurements with Machine Learning
  
  Abstract: Bluetooth Low Energy (BLE) distance estimation has many potential uses, but many require decent accuracy. This is often hindered by environmental factors such as interference and signal variability. This presentation introduces the potential of using machine learning techniques to address these challenges. I will outline the project’s objectives, planned methodology, and current progress.

• 11.12.2024 15:30-16:15 Mattis Bless and Maximilian Herych, Bachelor Project Kickoff

  Title: Efficient Shuffle for Mental Card Games 
  Efficient Shuffle for Mental Card Games - Theoretical Aspects (Mattis Bless)
  Efficient Shuffle for Mental Card Games - Practical Issues and Implementation (Maximilian Herych) 
  
  Abstract: Mental Card Games can be described as playing digital card games via networks without the need of a trusted party. Since there is no trusted party, everyone has to prove to or at least convince everyone else that nobody cheated in the game. This can be achieved by encoding the cards using a cipher system and applying zero-knowledge argument protocols. However, since the runtime affects the overall playability of the game, these protocols as well as the actual game should be implemented in an efficient way. Furthermore, there is no protocol which can just be applied to the entire game. Instead, the operations needed to play card games and either being performed on the cards directly, like playing a card, or on stacks of cards, like shuffling, have to be implemented as zero-knowledge arguments. Among these operations, shuffling is one of the more involved operations: A player shuffling a stack of cards or even the entire deck needs to convince every other player that the cards were shuffled correctly, meaning they were permuted without injecting new and removing old cards or just copying cards. At the same time, no other player should gain any information about the actual permutation since they could use this to their advantage. In current research, there are already several efficient zero-knowledge arguments for a shuffle of cipher texts. Applying such arguments to the shuffle operation in Mental Card Games serves as the basis of this project which consists of the following two parts: The first part deals with theoretical aspects regarding the applicability of different zero-knowledge shuffle arguments to the unique setting of Mental Card Games. This also includes considerations, for example, concerning the possibility of cheating by using different permutations for different parts of the encoding of the cards or hiding information about certain cards in the structure of the permutation. The second part consists of the implementation of the efficient shuffle while applying our considerations for safety in a Mental Card Game environment. The shuffle argument protocols will be implemented in Mathematica serving as a foundation for implementations in other languages.

• 20.11.2024, 14:00-14:30 Veena Srinivasan, Master Thesis Kickoff presentation
  
  Title: Evaluation of a New Mobile Communication Standard for Energy Efficient Sensor Meshes 
  
  Abstract: This thesis will be pursued in Endress + Hauser (E+H), Maulburg. E+H is an Industrial automation company which produces different types of sensors for monitoring parameters like flow, level, pressure and temperature. Given the recent advances in IIOT, the company has increased interest in researching and implementing modern communication protocols that can be used to create autonomous sensor networks. The topic of this research follows in the same direction. The abstract of the thesis is as follows.
  
  Use cases such as flood forecasting or monitoring of rivers and sewers often require many sensors distributed over a large area. In addition, the measuring points are often difficult to access, and devices must be largely autonomous and battery-operated to reliably transmit measured values over several years.
  
  New mobile radio standards such as DECT NR+ promise the development of self-managing and self-healing measurement networks that can be provisioned and operated in an energy-efficient manner.
  
  The aim of this thesis is to evaluate DECT NR+ regarding its applicability for energy-limited sensor systems. A prototype is to be developed with which the latency, throughput, range and energy consumption of a measurement network can be determined. In addition to energy consumption, particular attention will be paid to automatic provisioning and the distribution of over-the-air updates to all network nodes.
  
  The results will be compared with existing technologies such as WirelessHART or Bluetooth to decide whether DECT NR+ is a better alternative to these technologies. 
  
  Evaluation boards and internally developed microcontroller systems (using ARM M33) with corresponding modems will be used for this purpose. On the software side, the real-time operating system Zephyr RTOS will be used. Also, a distributed algorithm will be developed where the roles of the forwarding and routing nodes will be intelligently switched based on the energy levels available in the respective nodes.

• 20.11.2024, 15:00-15:30 Lukas Franz, Bachelor Project Kickoff presentation 
  
  Title: Relevant Lattice Code Research for Mental Card Game Applications
  
  Abstract: In this presentation, we explore the field of lattice cryptography, focusing on its foundational concepts and recent advancements. Lattice-based cryptographic schemes are widely regarded as secure against quantum attacks, making them a promising alternative to traditional cryptographic methods. The presentation begins with an introduction to lattice structures, key lattice problems such as the Shortest Vector Problem (SVP) and Closest Vector Problem (CVP), and their relevance to cryptographic protocols. We will then delve into specific applications, including Ajtai’s SIS function and Learning With Errors (LWE), which form the backbone of modern lattice-based cryptographic schemes.
  
  The second part of the talk will transition into a discussion on how lattice cryptography can be applied to mental card games, an area of research that remains largely unexplored. By reviewing current literature in lattice cryptography, I want to investigate how these techniques could work for mental card games. Providing efficient and secure operations for mental card game environments. Especially the shuffle operation will be interesting. This research could offer new insights into the intersection of post quantum cryptography and mental card games.

• 20.11.2024, 15:30-16:15, Jan Orlanski, Bachelor Project final presentation
  

  
  Title: Zero-Knowledge Proofs for Rule Control in Mental Card Games
  
  Abstract: The goal of mental card games is to ensure a secure and fair game without the need to blindly trust a third party. In this project, I specifically focus on enforcing the rules of the card game Uno and implement the necessary proofs using Mathematica. A game of Uno between two players is automatically simulated. Each time a player plays a card, a zero-knowledge proof is used to show that the card played was actually in that player's deck, without revealing which other cards are in the deck. In addition, there is a rule in Uno that says that the "Wild Draw Four" card can only be legally played if the player who wants to play it has no cards of the current color in their deck. To ensure that this condition is also met, the cards are encoded in such a way that the cards are represented by a different number of binary bits depending on their color. Bulletproof range proofs are then used to show that the player has no cards of the corresponding color in their deck

• 13.11.2024, 12:00-12:30 Mario Goltz, Bachelor Project Kickoff

  Topic: Simulated Dynamic Averaging Load Balancing for undirected Graph Types

  Abstract: In this project, we investigate the load balancing problem by comparing Dynamic Averaging Load Balancing by Berenbrink et al. with Peer-to-Peer Networks Based on Random Transformations by Mahlmann et al. These approaches aim to transfer loads to neighboring states in order to achieve balanced loads across the graph. The load on these graphs can represent various scenarios, such as the demand on video streaming servers, CPU core usage, and more. Consequently, load balancing seeks to distribute tasks across systems to ensure an even load, optimizing computational resource use. To provide a meaningful analysis, we implement the aforementioned load balancing approaches and evaluate them through simulations. The comparison is conducted on undirected graphs, including Torus, Grid, Lollipop, and Ring of Cliques structures. We measure performance based on the number of iterations required for load balancing on different graph types and sizes, the mean squared error, and the relative difference between the most and least loaded nodes, assessed in both relative and absolute terms.

• 23.10.2024, 14:00-14:30 Emre Bayazıtoglu's Bachelor Thesis Kickoff Presentation

  Title: Exploring Extensions of the Push-Pull Sum Protocol for Load Balancing in Peer-to-Peer Networks: Design, Implementation, and Comparative Analysis

  Abstract: The Push-Pull Sum protocol, introduced in [1], combines features of the Push-Sum [2] and Pull-Sum protocols. Push-Sum, originally proposed by Kempe et al., is a load-balancing algorithm where each node randomly selects a neighbor to transfer half of its sum and weight. Similarly, the Push-Pull Sum protocol operates as a randomized load-balancing mechanism in peer-to-peer networks, modeled as undirected graphs. Nodes exchange loads with their neighbors to reach a balanced state. In this thesis, I introduce and implement three variations of the Push-Pull Sum protocol, each enhancing or modifying key properties. These include a partly randomized approach, a threshold-based version, and a clustered approach. For each, I provide pseudocode, implement them in a simulation tool, and analyze outcomes across different topologies, focusing on properties like determinism, monotonicity, and faster convergence. The performance of these variations is evaluated through mean squared error (MSE) reduction over time, and results are visualized in log-log and log-linear graphs. This analysis compares convergence rates and stability in various scenarios, while also addressing potential drawbacks like increased communication overhead or slower convergence. 
  [1]: S. Nugroho, A. Weinmann, and C. Schindelhauer, "Adding Pull to Push Sum for Approximate Data Aggregation," Springer, 2023. 
  [2]: D. Kempe, A. Dobra, and J. Gehrke, "Gossip-based computation of aggregate information," 44th Annual IEEE Symposium on Foundations of Computer Science, 2003, pp. 482–491.

  23.10.2024, 15:00-15:45 Christian Schindelhauer, Impromptu Talk

  Title: Key Sharing Mechanisms for Mental Card Games

  Abstract: This talk explores three mechanisms for sharing public keys in Mental Card Games. The focus begins with operations that enable shared public keys for card manipulation, starting with the classical XOR scheme from S. 99. Next, we review the Stamer 2005 method based on Barnett and Smart, which utilizes ElGamal encryption and has become a standard. This method adds secret keys in the exponent. Finally, we discuss a third technique where secret keys are multiplied in the exponent, relying on a different homomorphic property. The talk will compare computational and message complexities, along with their relevance to asymmetric encryption systems.

• 16.10.2024, 14:00-14:30 Steven Kirschenbauer, Master Thesis intermediate presentation
  
  Title: Analysis of a paxcounter for non-invasive estimation of crowd density and pedestrian flow
  
  Abstract: This thesis analyzes a Bluetooth/BLE/WiFi-probe system ("paxcounter") for modeling and estimating crowd density and pedestrian flow in public spaces. It is part of the FreiburgRESIST project, which focuses on developing resilient digital strategies for emergency situations in urban areas, with an emphasis on real-time crowd monitoring and GDPR compliance.

• 16.10.2024, 15:00-15:30 Katsiaryna Mironava, Bachelor Project final presentation
  
  Title: Analyse und Umsetzung von OFI in Kryptografie als Vorbereitung zum Rezertifizierungsaudit des ISMS bei der JobRad GmbH
  
  Abstract: Im Rahmen meines Bachelorprojekts bei der JobRad GmbH lag der Fokus darauf, die Sicherheit und Effizienz der Speicherung kryptografischer Schlüssel angesichts aktueller Cyberbedrohungen zu optimieren. Zusätzlich untersuchte ich, ob die Implementierung eines Hardware-Sicherheitsmoduls (HSM) oder alternativer Module/Verfahren sinnvoll wäre. Ich prüfte die Aktualität der Richtlinie “Kryptografie”, um sicherzustellen, dass sie den aktuellen Anforderungen und Standards entspricht. Darüber hinaus wurden zusätzliche Standards und Leitfaden in diesem Bereich berücksichtigt. Anschließend erfolgte die Analyse der bestehenden Implementierung, um Abweichungen von den Anforderungen zu identifizieren. Im nächsten Schritt suchte ich nach einer angemessenen Lösung, um die Abweichungen zu beheben und die Implementierung zu optimieren. Letztendlich entschied ich mich aufgrund dieser Prüfung für eine alternative Optimierungslösung zur Speicherung kryptografischer Schlüssel, anstelle einer Integration des HSMs.
• 25.09.2024, 14:00-14:45 Ahmet Bulut, Master Thesis final presentation
  
  Title: Efficient ZK Argument for Shuffle Implementation in Rust
  
  Abstract: A shuffle operation in cryptography is an operation that takes a committed, anonymous series of values and returns the original series modified with a permuted order. It is an important operation in many real-world scenarios (e-voting, mental card games). Due to the plaintexts or data being encrypted for privacy, the correctness of a shuffle of commitments is not straightforward to verify. While there are algorithms to construct such arguments, we are providing the first comprehensive pure Rust library for the Correctness of a Shuffle Operation. The library is built over elliptic curve prime order groups to commit and encrypt data for privacy, while exploiting the homomorphism of the elliptic curves for efficiency. This argument for correctness combines two separate arguments (Multi-exponentiation Argument, Product Argument) to produce a Shuffle Argument for correctness. Utilizing the Rust programming language, with its efficiency in runtime and security in memory, we aim to provide an extensive and easy-to-use zero-knowledge proof framework that can be seamlessly incorporated and used by other proof schemes, or used to construct complex arguments.

• 18.09.2024, 14:00-14:45 Alex Lenitschek, Bachelor Thesis final presentation
  
  Title: Design, Implementation, Simulation and Evaluation of a Density-based Clustering Algorithm for Indoor Localization based on Directed and Reflected Signals
  
  Abstract: The Indoor Localization based on Directed and Reflected Signals (ILDARS) project aims to create a device capable of locating sound-emitting sources within unknown room environments by analyzing sound emissions like direct sounds or reflected sounds and the time difference between their arrival. This thesis focuses on a critical early stage of the ILDARS pipeline: clustering signals to determine wall positions. Specifically, an ILDARS-adapted version of the Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) algorithm is designed and implemented to effectively cluster the input data. The motivation behind this work lies in the crucial role accurate clustering plays in the overall ILDARS pipeline, as all subsequent algorithms rely on the precision of these initial clustering results for accurate source localization. The HDBSCAN algorithm is designed, implemented, simulated, and its performance across diverse virtual environments evaluated. The analysis considers various factors, such as room size, shape, and the presence of noise in the signal data, to assess the algorithm's robustness and effectiveness in clustering the data.

• 18.09.2024, 14:45-15:15 Peter Gillessen, Bachelor Project final presentation
  
  Title: Investigating HTTP/3 Request Smuggling Vulnerabilities in nginx
  
  Abstract: This project investigates potential HTTP/3 request smuggling vulnerabilities in the popular reverse-proxy nginx. Following the methodology proposed by Pisu et al., tests were conducted using an environment that forces HTTP/3 to HTTP/1.1 conversions. Out of 203 malformed HTTP/3 requests, 201 were successfully rejected or modified, adhering to RFC 9114. However, two requests containing disallowed ASCII characters (0x20 and 0x9) in header values were forwarded unmodified to the backend, indicating a potential risk for request smuggling. These findings highlight the need for further investigation into specific edge cases, despite the overall robustness of nginx in handling such vulnerabilities.

• 11.09.2024, 13:00-13:30 Emre Bayazıtoglu, Bachelor Project final presentation
  
  Title: Comparative Analysis of Load Balancing Algorithms in General Graphs
  
  Abstract: In this work, we study the load balancing problem comparing the Push-Pull Sum protocol proposed in Nugroho et al. [1] to the Single Proposal Load Balancing protocol proposed in Dinitz et al. [2]. In undirected graphs, nodes can transfer loads to their neighbors, aiming to achieve a balanced state in the network. These loads may represent computational tasks related to CPU usage, memory utilization, or even internet traffic. Balancing loads helps improve the efficacy of distributed systems and prevent system and performance errors. In cloud computing, load balancing algorithms are crucial for improving response times, ensuring system stability, and contributing to customer satisfaction. We implemented the aforementioned load balancing algorithms and evaluated their performance through simulations. Simulations were conducted using the PeerSim simulation tool, comparing the progression of the mean squared error across multiple computation rounds. The simulations were performed on various topologies to identify the limitations and strengths of each algorithm.