Publications

2020

  • Roman Matzutt, Jan Pennekamp, Erik Buchholz, and Klaus Wehrle. Utilizing Public Blockchains for the Sybil-Resistant Bootstrapping of Distributed Anonymity Services. In Proceedings of the 15th ACM ASIA Conference on Computer and Communications Security (ASIACCS ’20), 10 2020.
    [BibTeX] [Abstract] [DOI] [PDF] [CODE]
    Distributed anonymity services, such as onion routing networks or cryptocurrency tumblers, promise privacy protection without trusted third parties. While the security of these services is often well-researched, security implications of their required bootstrapping processes are usually neglected: Users either jointly conduct the anonymization themselves or they need to rely on a set of non-colluding privacy peers. However, the typically small number of privacy peers enable single adversaries to mimic distributed services. We thus present AnonBoot, a Sybil-resistant medium to securely bootstrap distributed anonymity services via public blockchains. AnonBoot enforces that peers periodically create a small proof of work to refresh their eligibility of providing secure anonymity services. A pseudo-random, locally replicable bootstrapping process using on-chain entropy then prevents biasing the election of eligible peers. Our evaluation using Bitcoin as AnonBoot’s underlying blockchain shows its feasibility to maintain a trustworthy repository of 1000 peers with only a small storage footprint while supporting arbitrarily large user bases on top of most blockchains.
    @inproceedings{MPBW20,
    author = {Matzutt, Roman and Pennekamp, Jan and Buchholz, Erik and Wehrle, Klaus},
    title = {{Utilizing Public Blockchains for the Sybil-Resistant Bootstrapping of Distributed Anonymity Services}},
    booktitle = {Proceedings of the 15th ACM ASIA Conference on Computer and Communications Security (ASIACCS '20)},
    minimal = {},
    year = {2020},
    month = {10},
    doi = {10.1145/3320269.3384729},
    abstract = {Distributed anonymity services, such as onion routing networks or cryptocurrency tumblers, promise privacy protection without trusted third parties. While the security of these services is often well-researched, security implications of their required bootstrapping processes are usually neglected: Users either jointly conduct the anonymization themselves or they need to rely on a set of non-colluding privacy peers. However, the typically small number of privacy peers enable single adversaries to mimic distributed services. We thus present AnonBoot, a Sybil-resistant medium to securely bootstrap distributed anonymity services via public blockchains. AnonBoot enforces that peers periodically create a small proof of work to refresh their eligibility of providing secure anonymity services. A pseudo-random, locally replicable bootstrapping process using on-chain entropy then prevents biasing the election of eligible peers. Our evaluation using Bitcoin as AnonBoot's underlying blockchain shows its feasibility to maintain a trustworthy repository of 1000 peers with only a small storage footprint while supporting arbitrarily large user bases on top of most blockchains.},
    code = {https://github.com/COMSYS/anonboot},
    meta = {},
    }

University Papers

  • Master Thesis: Ongoing (COMSYS, RWTH Aachen University)
  • Master Seminar: App Fingerprinting (ITSEC, RWTH Aachen University)
  • Bachelor Thesis: A User-controlled Data Market for Privacy-preserving Data Analyses
    Advised by Prof. Dr.-Ing. Klaus Wehrle (COMSYS, RWTH Aachen University) and Prof. Dr. Bernhard Rumpe (SE, RWTH Aachen University)
  • Bachelor Seminar: Bloom CookiesFOLKS Best Paper Award (COMSYS, RWTH Aachen University)