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Department of Informatics - Communication Systems Group

Tracking Trackers and Bridging Legal, Technical, and Human Perspectives on Privacy in Crowdsourced Location Networks

TRACE Scenario
Scenario: We are all connected through Bluetooth devices everywhere we go. Image AI enhanced. 

Today, most of us carry several wireless devices every day, including smartphones, headphones, smartwatches, tablets, laptops, and smart accessories such as AirTags. These devices constantly communicate with each other and with nearby devices to make technology feel seamless and convenient. This allows headphones to switch automatically between a phone and a laptop, smartwatches to stay connected, or lost keys to be found through crowdsourced location networks.

What often goes unnoticed is that convenience depends on this continuous and invisible background wireless communication. Even when these messages are encrypted, they can still reveal surprising amounts of information through their timing, frequency, size, and communication patterns. By studying these hidden signals, it is possible to learn what types of devices are nearby, whether devices belong together, how people move through spaces, and in some cases whether a device may pose a threat to someone’s privacy or safety.

Our research investigates both the benefits and the risks of these technologies. In particular, we study how tracking devices such as AirTags can be misused for stalking or unwanted surveillance, while also exploring ways to better detect suspicious devices and improve privacy protections for users. The project combines technical, legal, and human-centered perspectives to better understand how privacy and personal safety can be protected in a world increasingly shaped by pervasive sensing technologies.

Publications

  • Katharina Olga Emilia Müller, Louis Bienz, Bruno Bastos Rodrigues, Chao Feng, Burkhard Stiller: HomeScout: Anti-Stalking Mobile App for Bluetooth Low Energy Devices; The 48th IEEE Conference on Local Computer Networks (LCN), Daytona Beach, Florida, U.S.A., October 2023, pp 1–8.
  • Katharina Olga Emilia Müller, Delia Datsomor, Daria Schumm, Bruno Bastos Rodrigues, Burkhard Stiller: Big Brother is Watching You: Non-Intrusive ZigBee User Profiling; 20th International Conference on Network and Service Management, "IEEE CNSM 2024", Prague, Czech Republic, October 2024, pp 1–7.
  • Katharina O.E. Müller, Samuel Frank1, Dario Monopoli, Daria Schumm, Bruno Rodrigues, Burkhard Stiller: Smart Shielding: Using ML and AirTag RSSI Data for Better Privacy; The 50th IEEE Conference on Local Computer Networks (LCN), Sydney, Australia, October 2025, pp 1–7.
  • Katharina O. E. Müller, Stefan Saxer, Daria Schumm, Weijie Niu, Bruno Rodrigues, Burkhard Stiller: AirTagged: A Dataset and Processing Framework for Heterogeneous High-Density IoT Environments:  21st International Conference on Network and Service Management, "IEEE CNSM 2025", Bologna, Italy, October 2025, pp 1–7.
  • Katharina O. E. Müller, Keisuke Yokota, Weijie Niu, Daria Schumm, Burkhard Stiller: Towards Markov Synthetic BLE Packet Generation for IoT Systems;  21st International Conference on Network and Service Management, "IEEE CNSM 2025", Bologna, Italy, October 2025, pp 1–7.
  • Katharina O. E. Müller, Stefan R. Saxer, Daria Schumm, Bruno Rodrigues, Burkhard Stiller: Tracking Trackers: ML-Based Personal Tracker Detection in Crowded IoT Environments; 31st IEEE Symposium on Computers and Communications (ISCC), Vilamoura, Algarve, Portugal, June 2026, pp 1–7.

Prototypes

The prototypes and Proof of Concept Implementations have been published on GitHub: 

Datasets

Personal Tracker Dataset

UZH Personnel and Contributors