François-Xavier Wicht

PhD student

Research statement

I’m a PhD student in the Cryptology and Data Security Group at the University of Bern, working on the privacy and scalability of digital currencies, covering both decentralized cryptocurrencies and centrally managed systems like CBDCs.

A core part of my research is developing formal definitions for privacy: ways to precisely characterize and compare the guarantees different systems provide. From there, I design cryptosystems that can provably meet those definitions or introduce new privacy properties altogether. I’m also interested in the storage overhead that privacy-preserving mechanisms introduce and the consequences this has on node synchronization. More broadly, my interests include privacy-enhancing technologies and censorship-resistant systems, drawing on cryptography and Byzantine fault-tolerant protocols.

The work is also interdisciplinary: I collaborate with legal researchers and think a lot about how to meaningfully balance privacy and regulatory oversight. This tension isn’t unique to digital currencies; it runs through the traditional financial system too. Building mechanisms where people have real privacy and regulators can still act when it matters is one of the things I find most exciting about this field. Beyond compliance, cryptography lets us enforce rules at a technical level, offering protection against regime change or corruption that no legal framework alone can guarantee.

More information is available on my personal page.

Teaching

• Fall Semester 2023: Diskrete Mathematik
• Fall Semester 2024: Distributed Algorithms
• Spring Semester 2026: Privacy and Data Security
• Spring Semester 2026: Seminar on Usable Security

Bachelor and Master thesis

Besides the list of available thesis topics, I stand available to discuss interesting ideas and supervise potential thesis topics.

Publications

1. Cachin, C., & Wicht, F.-X. (2025). Toxic Decoys: A Path to Scaling Privacy-Preserving Cryptocurrencies. Proceedings on Privacy Enhancing Technologies, 2025(4), 926–943. https://doi.org/10.56553/popets-2025-0165
2. de Laage, R., Yuhala, P., Wicht, F.-X., Felber, P., Cachin, C., & Schiavoni, V. (2025). Practical Secure Aggregation by Combining Cryptography and Trusted Execution Environments. Proc. Distributed and Event-Based Systems (DEBS), 152–163. https://doi.org/10.1145/3701717.3730543
3. Wicht, F.-X., Wang, Z., Le, D. V., & Cachin, C. (2025). A Transaction-Level Model for Blockchain Privacy. In J. Clark & E. Shi (Eds.), Proc. 28th International Conference on Financial Cryptography and Data Security (FC) (Vol. 14745). Springer. https://doi.org/10.1007/978-3-031-78679-2_16
4. Amores-Sesar, I., Cachin, C., Chatterjee, R., Soezima, L., Wicht, F.-X., & Yeo, M. (2026). Track Me If You Can: Ephemeral Coin Tracing. e-print, arXiv:2608.09249 [cs.CR]. https://arxiv.org/abs/2608.09249
5. Cachin, C., Lehnherr, D., Villacis, J., & Wicht, F.-X. (2026). The Consensus Number of Untraceable Cryptocurrencies. Cryptology ePrint Archive, Paper 2026/1503. https://eprint.iacr.org/2026/1503
6. Wicht, F.-X., Tong, Z., Zhou, S., Yin, H., & Yaish, A. (2025). Persistent BitTorrent Trackers. Cryptology ePrint Archive, Paper 2025/2131. https://eprint.iacr.org/2025/2131