Biography
I am a junior research group leader for data protection and sovereignty with Fraunhofer FIT.
I joined Fraunhofer FIT in 2023 after concluding my PhD with COMSYS at RWTH Aachen University.
My main research interests are the scenario-specific application of blockchain technology as well as the design of privacy-enhancing systems.
Blockchain technology, as introduced by Bitcoin, constitutes a virtually unchangeable log of events, e.g., financial transactions, and thereby eliminates attacks such as equivocation.
In my research, I am interested in general properties of blockchains as well as their applications, e.g., to improve the trustworthiness of existing systems and to discover entirely novel use cases.
Privacy-enhancing technologies (PETs) usually comprise basic principles and technologies that can be utilized to increase user privacy.
With respect to privacy-enhancing systems, I am interested in developing new architectures that allow to utilize PETs in novel ways and thereby further reduce the trust users are required to put into the online services they use.
Featured Publications
Eric Wagner, Roman Matzutt, Martin Henze Transactions on Privacy and Security, 29(2):1-30
While anonymity networks such as Tor provide invaluable privacy guarantees to society, they also enable all kinds of criminal activities. Consequently, many blameless citizens shy away from protecting their privacy using such technology for fear of being associated with criminals. To grasp the potential for alternative privacy protection for those users, we design Seldom, an anonymity network with integrated selective deanonymization that disincentivizes criminal activity. Seldom enables law enforcement agencies to selectively access otherwise anonymized identities of misbehaving users while providing technical guarantees preventing these access rights from being misused. Seldom further ensures translucency, as each access request is approved by a trustworthy consortium of impartial entities and eventually disclosed to the public (without interfering with ongoing investigations). To demonstrate Seldom’s feasibility and applicability, we base our implementation on Tor, the most widely used anonymity network. Our evaluation indicates minimal latency, processing, and bandwidth overheads compared to Tor; Seldom’s main costs stem from storing flow records and encrypted identities. With at most 636 TB of storage required in total to retain the encrypted identifiers of a Tor-sized network for two years, Seldom provides a practical and deployable technical solution to the inherent problem of criminal activities in anonymity networks. As such, Seldom sheds new light on the potentials and limitations when integrating selective deanonymization into anonymity networks.
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ACM DL
Code
arXiv
@article{2026-acmtops-wagner-seldom,
author = {Wagner, Eric and Matzutt, Roman and Henze, Martin},
title = {{Seldom: An Anonymity Network with Selective Deanonymization}},
journal = {Transactions on Privacy and Security},
publisher = {ACM},
year = {2026},
volume = {29},
number = {2},
month = {3},
pages = {1--30},
keywords = {Tor, Exceptional Access, Translucent Ledger, Threshold Encryption},
issn = {},
doi = {10.1145/3794848},
}
Roman Matzutt PhD thesis
Bitcoin introduced the blockchain as a decentralized data structure to establish consensus about who owns which coins. Since then, blockchain technology has evolved and now enables distrusting parties to engage in various online interactions without trusted intermediaries.
However, this technology is not without its own shortcomings. While prior work has extensively studied technical challenges, it neglected the influence of the data stored on the blockchain so far. In this dissertation, we take a data-driven perspective to assess and improve permissionless blockchains as building blocks for decentralized data management systems. We identify two core challenges, i.e., the need for moderating what data is recorded and the need for alleviating the storage requirements of ever-growing blockchains, and assess the technology’s potential to foster further applications.
With the four contributions we present in this dissertation, we shed new light on the potential impact of the data persisted on blockchains. Our analyses and technical contributions therefore widen the scope for resilient and durable blockchain designs for data management tasks.
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Publisher Page
Amazon
@phdthesis{2024-phdthesis-matzutt-blockchain-data-management,
author = {Matzutt, Roman},
title = {{Demystifying and Adjusting the Promises of Blockchain-based Data Management in the Permissionless Setting}},
school = {RWTH Aachen University},
year = {2024},
}
Jan Pennekamp, Roman Matzutt, Christopher Klinkmüller, Lennart Bader, Martin Serror, Eric Wagner, Sidra Malik, Maria Spiß, Jessica Rahn, Tan Gürpinar, Eduard Vlad, Sander J. J. Leemans, Salil S. Kanhere, Volker Stich, Klaus Wehrle Computing Surveys, 56(2):1-38
We assess the current state of the art regarding security and reliability of information flows in supply chains. Our systematic literature review covering over a decade of survey articles reveals an unexpected technological gap: While technical building blocks for protecting informations flows are theoretically available, they have not yet found widespread applications in protecting supply-chain information flows. Thus, we derive a taxonomy for describing characterstics of supply-chain data flows and propose future research directions toward closing this gap.
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ACM DL
Kudos
@article{2023-csur-pennekamp-scsok,
author = {Pennekamp, Jan and Matzutt, Roman and Klinkm{\"u}ller, Christopher and Bader, Lennart and Serror, Martin and Wagner, Eric and Malik, Sidra and Spi{\ss}, Maria and Rahn, Jessica and G{\"u}rpinar, Tan and Vlad, Eduard and Leemans, Sander J. J. and Kanhere, Salil S. and Stich, Volker and Wehrle, Klaus},
title = {{An Interdisciplinary Survey on Information Flows in Supply Chains}},
journal = {Computing Surveys},
publisher = {ACM},
year = {2023},
volume = {56},
number = {2},
month = {9},
pages = {1--38},
keywords = {information flows, data communication, supply chain management, data security, data sharing, systematic literature review},
issn = {0360-0300},
doi = {10.1145/3606693},
}
Roman Matzutt, Vincent Ahlrichs, Jan Pennekamp, Roman Karwacik, Klaus Wehrle Proceedings of the 2022 IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2022)
In this paper, we propose a moderation framework, RedactChain, that allows small and periodically replaced juries to redact transactions from a Bitcoin-like blockchain, e.g., when users report illicit content being engraved on the blockchain. In contrast to previous schemes, our approach enables the swift and transparent removal of such content while keeping per-redaction overheads low. Furthermore, RedactChain defines rules to handle the redaction of manipulated transactions, whose outputs hold currency and might be spendable, without affecting the transaction graph. Namely, spendable outputs are obfuscated such that their content cannot be retrieved anymore, but the output’s associated coins remain spendable.
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Code
IEEE Xplore
@inproceedings{2022-icbc-matzutt-redactchain,
author = {Matzutt, Roman and Ahlrichs, Vincent and Pennekamp, Jan and Karwacik, Roman and Wehrle, Klaus},
title = {{A Moderation Framework for the Swift and Transparent Removal of Illicit Blockchain Content}},
booktitle = {Proceedings of the 2022 IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2022)},
publisher = {IEEE},
year = {2022},
pages = {},
keywords = {redactable blockchain, illicit content, chameleon hash functions, threshold cryptography},
isbn = {978-1-6654-9538-7},
doi = {10.1109/ICBC54727.2022.9805508},
}
Roman Matzutt, Benedikt Kalde, Jan Pennekamp, Arthur Drichel, Martin Henze, Klaus Wehrle Transactions on Network and Service Management, 18(3):3064-3078
In this paper, we present the full design of CoinPrune, our block-pruning protocol that is retrofittable to Bitcoin via a velvet fork. This work extends our initial paper presented at IFIP Networking 2020 by enabling CoinPrune to obfuscate most objectionable content stored in the UTXO set and introducing an additional store for application-level data. Furthermore, we extend our security discussion, our discussion of related work, we updated our performance evaluation, and we released a prototype implementation of CoinPrune.
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Code
Dataset
IEEE Xplore
@article{2021-ieeetnsm-matzutt-coinprune-v2,
author = {Matzutt, Roman and Kalde, Benedikt and Pennekamp, Jan and Drichel, Arthur and Henze, Martin and Wehrle, Klaus},
title = {{CoinPrune: Shrinking Bitcoin's Blockchain Retrospectively}},
journal = {Transactions on Network and Service Management},
publisher = {IEEE},
year = {2021},
volume = {18},
number = {3},
month = {9},
pages = {3064--3078},
keywords = {blockchain, block pruning, synchronization, bootstrapping, scalability, velvet fork, Bitcoin},
issn = {1932-4537},
doi = {10.1109/TNSM.2021.3073270},
}
Roman Matzutt, Jan Pennekamp, Erik Buchholz, Klaus Wehrle 15th ACM ASIA Conference on Computer and Communications Security (ACM ASIACCS 2020)
We present AnonBoot, an architecture for securely bootstrapping anonymity services seizing a public blockchain as a trust anchor. Through periodic peer advertisements, we create a Sybil-resistant repository of privacy peers that can be directly utilized to establish circuits for onion routing networks, or that can be elected to establish small distributed anonymity services such as mixnets or cryptotumblers. Our proof-of-concept implementation shows how AnonBoot can operate even on simple public blockchains such as Bitcoin.
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Code
ACM DL
arXiv
@inproceedings{2020-asiaccs-matzutt-anonboot,
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 = {15th ACM ASIA Conference on Computer and Communications Security (ACM ASIACCS 2020)},
publisher = {ACM},
year = {2020},
pages = {531--542},
keywords = {anonymization, bootstrapping, public blockchain, Sybil attack, anonymity network, cryptocurrency tumbler, Bitcoin, Tor},
isbn = {978-1-4503-6750-9/20/10},
doi = {10.1145/3320269.3384729},
}
Roman Matzutt, Martin Henze, Jan Henrik Ziegeldorf, Jens Hiller, Klaus Wehrle Proceedings of the First IEEE Workshop on Blockchain Technologies and Applications, co-located with the IEEE International Conference on Cloud Engineering 2018 (BTA 2018), Workshop paper
Since the insertion of illicit content into public blockchains can have severe consequences for users, we explore and discuss the design space for preventing this insertion. Our findings show that firewall-like scanning of Bitcoin transactions poses no viable solution to the problem. However, while content insertion cannot entirely be prevented by technical means, self-verifying blockchain identifiers make currently simple manipulations hard. Finally, the introduction of mandatory minimum fees can be used to disincentivize content insertion additionally.
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IEEE Xplore
Website
@inproceedings{2018-bta-matzutt-bitcoin-content-countermeasures,
author = {Matzutt, Roman and Henze, Martin and Ziegeldorf, Jan Henrik and Hiller, Jens and Wehrle, Klaus},
title = {{Thwarting Unwanted Blockchain Content Insertion}},
booktitle = {Proceedings of the First IEEE Workshop on Blockchain Technologies and Applications, co-located with the IEEE International Conference on Cloud Engineering 2018 (BTA 2018)},
publisher = {IEEE},
year = {2018},
pages = {364--370},
keywords = {Bitcoin, blockchain, security, objectionable content, countermeasure},
isbn = {978-1-5386-5008-0},
doi = {10.1109/IC2E.2018.00070},
}
Jan Henrik Ziegeldorf, Roman Matzutt, Martin Henze, Fred Grossmann, Klaus Wehrle Future Generation Computer Systems, 80:448-466
CoinParty is a fully decentralized and thus secure Bitcoin mixing service. Our work uses threshold cryptography to combine the adavantages of centralized and decentralized mixers: high usability and strong security guarantees.
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Code
@article{2018-fgcs-ziegeldorf-coinparty-v2,
author = {Ziegeldorf, Jan Henrik and Matzutt, Roman and Henze, Martin and Grossmann, Fred and Wehrle, Klaus},
title = {{Secure and anonymous decentralized Bitcoin mixing}},
journal = {Future Generation Computer Systems},
publisher = {Elsevier},
year = {2018},
volume = {80},
number = {},
month = {3},
pages = {448--466},
keywords = {Bitcoin, digital cash, privacy-preserving protocols, pseudonymity, anonymity, untraceability},
issn = {0167-739X},
doi = {10.1016/j.future.2016.05.018},
}
Roman Matzutt, Jens Hiller, Martin Henze, Jan Henrik Ziegeldorf, Dirk Müllmann, Oliver Hohlfeld, Klaus Wehrle Financial Cryptography and Data Security 2018 (FC ‘18)
We survey methods enabling the insertion of arbitrary content into Bitcoin’s blockchain, quantitatively analyze their utilization, both directly and via content insertion services, and assess potential consequences of being forced to keep potentially illicit content on the users’ hard disks. Our findings show that arguably objectionable content has already been inserted to Bitcoin’s blockchain and that it can lead to legal liability for users in jurisdictions such as Germany.
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The Morning Paper
Website
Springer
@inproceedings{2018-fc-matzutt-bitcoin-contents,
author = {Matzutt, Roman and Hiller, Jens and Henze, Martin and Ziegeldorf, Jan Henrik and M{\"u}llmann, Dirk and Hohlfeld, Oliver and Wehrle, Klaus},
title = {{A Quantitative Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin}},
booktitle = {Financial Cryptography and Data Security 2018 (FC ‘18)},
publisher = {Springer},
year = {2018},
pages = {420--438},
keywords = {},
isbn = {},
doi = {10.1007/978-3-662-58387-6_23},
}