Publications

I enjoy collaborating with other researchers. During my PhD I collaborated with Luca Zanolini, now at Ethereum Foundation, on topics including consensus protocols, general and asymmetric trust assumptions, and composition of distributed systems. Moreover, with Duc V. Le, staff research scientist at VISA Research, we worked on polynomial commitments and digital signatures. With Giorgia Azzurra Marson from NEC Laboratories Europe we explored foundational properties of smart contracts. At the same time, I (co-)supervised 3 MSc and 9 BSc student theses on topics related to cryptography and blockchains, and (sub-)reviewed multiple academic papers.

In September 2022 I visited the crypto group at the Aarhus University. With Simon Holmgaard Kamp and Jesper Buus Nielsen we developed an asynchronous consensus protocol for proof-of-stake blockchains.

2025

• Pod: An Optimal-Latency, Censorship-Free, and Accountable Generalized Consensus Layer
  Orestis Alpos, Bernardo David, Dionysis Zindros
  (under submission)
  Deployed on the pod blockchain!

• Thetacrypt: A Distributed Service for Threshold Cryptography
  Mariarosaria Barbaraci, Noah Schmid, Orestis Alpos, Michael Senn, Christian Cachin.
  (under submission)

2024

• Asymmetric distributed trust
  Orestis Alpos, Christian Cachin, Björn Tackmann, Luca Zanolini.
  In Distributed Computing Journal, 2024.

2023 - 2020

• Distributed Protocols with Threshold and General Trust Assumptions
  PhD thesis, Orestis Alpos. University of Bern, 2023
  See related blogpost.

• Practical large-scale proof-of-stake asynchronous total-order broadcast
  O. Alpos, C. Cachin, S. H. Kamp, and J. B. Nielsen.
  In Advances in Financial Technology, AFT 2023.

• Thetacrypt: A Distributed Service for Threshold Cryptography On-Demand: Demo Abstract
  Orestis Alpos, Mariarosaria Barbaraci, Christian Cachin, Noah Schmid, Michael Senn.
  In Middleware Conference 2023.
  Open source implementation of Thetacrypt.

• DSKE: Digital signature with key extraction
  O. Alpos, Z. Wang, A. Kavousi, S. Y. Chau, D. Le, and C. Cachin.
  To appear in the proceedings of CT-RSA 2025

• Eating sandwiches: Modular and lightweight elimination of transaction reordering attacks
  O. Alpos, I. Amores-Sesar, C. Cachin, and M. Yeo.
  In International Conference on Principles of Distributed Systems, OPODIS 2023.

• Do not trust in numbers: Practical distributed cryptography with general trust
  O. Alpos and C. Cachin.
  In Symposium on Stabilization, Safety and Security of Distributed Systems, SSS 2023.
  Best paper award!

• How to Trust Strangers: Composition of Byzantine Quorum Systems
  O. Alpos, C. Cachin, and L. Zanolini.
  In IEEE Symposium on Reliable Distributed Systems, SRDS 2021.
  See related blogpost.

• On the Synchronization Power of Token Smart Contracts
  O. Alpos, C. Cachin, G. A. Marson, and L. Zanolini.
  In IEEE International Conference on Distributed Computing Systems, ICDCS 2021.
  See related blogpost and presentation.

• Consensus Beyond Thresholds: Generalized Byzantine Quorums Made Live
  O. Alpos and C. Cachin.
  In IEEE Symposium on Reliable Distributed Systems, SRDS 2020.
  See related blogpost and presentation.