News
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DAG-based asymmetric consensus
The research paper DAG-based Consensus with Asymmetric Trust has been accepted for presentation and publication at the PODC 2025 conference, the 44th ACM Symposium on Principles of Distributed Computing, which is held in Santa María Huatulco, Mexico, in June 2025. This work addresses the asymmetric-trust model, in which each participant is free to make its own subjective and individual trust assumptions about others. The paper shows the first asymmetric protocol for computing a common core, equivalent to that in the threshold model. Implementing this primitive then leads to the first randomized asynchronous DAG-based consensus protocol with asymmetric quorums,
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Best student paper award for David Lehnherr
The research paper Simplicial Belief has been accepted to the SIROCCO 2025 conference, the 32nd International Colloquium On Structural Information and Communication Complexity. SIROCCO is devoted to the study of the interplay between structural knowledge, communication, and computing in decentralized systems of multiple communicating entities.
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Seminar on blockchains and cryptocurrencies
In the fall semester 2024, a seminar in the Joint Master in Computer Science at the University of Bern was offered by the CRYPTO group and focused on blockchains and cryptocurrencies.
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New team members: Vivien Bammert and Annalisa Cimatti
In November 2024 Vivien Bammert has joined the CRYPTO group as a researcher and Ph.D. student. Her background is in algebra, coding theory, and code-based cryptography. She holds a M.Sc. in mathematics from the University of Zurich.
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Boquila project wins hackathon at the 2024 IC3 Blockchain Camp
The CRYPTO group has integrated some of its research with the Initiative for CryptoCurrencies and Contracts (IC3), a blockchain research effort based at Cornell Tech in New York. In the context of this collaboration, Jayamine Alupotha and Mariarosaria Barbaraci participated in the annual IC3 Blockchain Camp earlier in June.
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Welcome, Juan Villacis
Juan Villacis has joined the CRYPTO research team as a Ph.D. student in June 2024. Prior to that, he obtained a B.Sc. degree from the Costa Rica Institute of Technology and a M.Sc. degree in Computer Science from ETH Zurich.
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Avalanche Consensus - Does it Perform as Promised?
We have recently looked at the “Snow” consensus protocols. They were introduced in a whitepaper by a team that later went on to found Ava Labs and pioneered the Avalanche blockchain infrastructure. The corresponding research paper is presented at SIROCCO 2024 and appears in the proceedings; a complete version can be found in a technical report.
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Eating Sandwiches: Modular and Lightweight Elimination of Transaction Reordering Attacks
The problems of maximal-extractable value (MEV) and front-running attacks have plagued decentralized finance (DeFi) in the recent years. Recent work published at OPODIS 2023 addresses the problem of sandwich attacks in general way and introduces a protocol to transform any blockchain consensus algorithm into a new one that has the same security, but in which sandwich attacks are no longer profitable.
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Asymmetric Distributed Trust - An Update
Trust in blockchain networks has traditionally been symmetric, such that all nodes in a system use one common assumption about potential faults. Such trust is homogeneous, now it becomes heterogeneous.
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Overview of courses
Here is an overview of the planned course offerings.
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Ph.D. degree for Jovana Milojević
On 7 March 2024, Jovana Milojević passed the Ph.D. examination with her thesis titled “Security and Fairness of Blockchain Consensus Protocols”. She did most of the research leading to this degree as Jovana Mićić. The external examiner was Pascal Felber from the University of Neuchatel. Congratulations!
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Ph.D. degree for Ignacio Amores Sesar
Ignacio Amores Sesar successfully defended his Ph.D. thesis “Scaling the Unscalable: A Study About Consensus” today. Congratulations! Many thanks to Arthur Gervais of UCL for serving as external examiner.
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IC3 Winter Retreat 2024
Most of the team has participated in the Winter Retreat 2024 of the Initiative for Cryptocurrencies and Contracts (IC3), a joint research initiative of faculty members from many leading universities in the space of blockchain research. The event featured more than two days of insightful presentations and discussions, opportunities to connect with fellow researchers, industry experts, and IC3 partners, as well as networking and group activities to foster collaborations.
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Ph.D. degree for Orestis Alpos
On 23 August 2023, Orestis Alpos defended successfully his Ph.D. thesis “Distributed protocols with threshold and general trust assumptions”. The external examiner was Jesper Buus Nielsen from Aarhus University. Congratulations!
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Summer retreat 2023 in Ligerz
The CRYPTO group organized a retreat in Ligerz on beautiful Bielersee in July. All members gave insight into their current research work and explored future research ideas together. Everyone also presented some technical topic outside their comfort zone. A hike through the Twannbachschlucht concluded the event.
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Welcome, Jayamine Alupotha and Michael Senn
In May and July 2023, two researchers joined the team. Jayamine Alupotha obtained a Ph.D. degree in Computer Science from Queensland University of Technology (QUT) in Australia, with specialization in cryptography. She works in the area of secure distributed consensus protocols.
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Ph.D. degree for Luca Zanolini
Luca Zanolini passed his Ph.D. exam successfully on 6 July 2023. His thesis is titled “Asymmetric Trust in Distributed Systems” The external examiner was Rachid Guerraoui, but he could not attend in person unfortunately. Congratulations!
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New team members: Philipp Schneider and François-Xavier Wicht
In February 2023, Philipp Schneider has started as a postdoc in the CRYPTO research group. He holds a Ph.D. in computer science from the University of Freiburg (Germany), where he worked in the area of distributed algorithms.
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New project on the digital transformation of central bank money
Cryptocurrencies based on blockchain technology have been created as an alternative to regulated financial markets. But the almost 15-year history of Bitcoin, digital ledgers, and decentralized finance shows that these digital systems do not live in a vacuum: they exist for and through people.
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Seminar in Civil Law and Computer Science
Interdisciplinary Seminar in Civil Law and Computer Science - Distributed Trust in Finance
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Quorum systems in permissionless networks
Our recent work on Quorum Systems in Permissionless Networks will be presented at the OPODIS 2022 conference. It is coauthored by Luca Zanolini and Christian Cachin of the University of Bern and Giuliano Losa of the Stellar Development Foundation.
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A security analysis of Avalanche consensus
Spring is coming - When does the snow melt?
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Crypto-events mailing list
The Cryptology and Data Security Research Group operates a mailing list for annoucements of talks in Bern and some occasional news items.
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Welcome, Mariarosaria Barbaraci
Mariarosaria Barbaraci has joined the CRYPTO research group in July 2022. She graduated with a Master of Science in Computer Engineering from Università degli studi di Napoli Federico II.
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Sebati Ghosh joins from Indian Statistical Institute, Kolkata
Sebati Ghosh has joined the Cryptology and Data Security group in March 2022.
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Differential order-fairness and quick order-fair atomic broadcast
A new, efficient protocol eliminates attacks on decentralized finance platforms and ensures a novel notion of differential order-fairness for transactions in atomic broadcast.
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Duc V. Le joins the group from Purdue University
Welcome, Duc V. Le, to the Cryptology and Data Security group!
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David Lehnherr joins the team
In October 2021, David Lehnherr has joined the team as a Ph.D. student. He graduated with a M.Sc. degree in Computer Science from the University of Bern in 2021. In his M.Sc. thesis he developed a logic of interactive proofs and is now looking into concurrency and cryptographic protocols in secure distributed systems.
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How to Trust Strangers
Trust is the basis of any distributed, fault-tolerant, or secure system. A trust assumption specifies the failures that a system, such as a blockchain network, can tolerate and determines the conditions under which it operates correctly. In systems subject to Byzantine faults, the trust assumption is usually specified through sets of processes that may fail together. Trust has traditionally been symmetric, such that all processes in the system adhere to the same, global assumption about potential faults. Recently, asymmetric trust models have also been considered, especially in the context of blockchains, where every participant is free to choose who to trust.
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Seminar Civil Law and Computer Science
In the spring term 2021, the Institute for Civil Law and the Institute of Computer Science jointly organized an interdisciplinary seminar with participants from the Faculty of Law and from the Faculty of Science.
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Synchronization power of smart contracts
Our recent research on the synchronization power of smart contracts explores the scalability of blockchain networks.
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Nathalie Steinhauer joins the group
Welcome back, Nathalie Steinhauer! As of April 2021, Nathalie has joined the team as a Ph.D. student. She graduated with a M.Sc. degree in Computer Science from the University of Bern in early 2020. Her M.Sc. thesis addressed a practical implementation of distributed cryptography and was already carried out at the Cryptology and Data Security research group.
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New interdisciplinary Seminar in Civil Law and Computer Science
The Institute for Civil Law and the Institute of Computer Science will hold an interdisciplinary seminar on the topic of Distributed Trust and Blockchain. Students of computer science and law and will work closely together on questions concerning the blockchain and its potential in the legal domain. The goal of the seminar is to explore how the characteristics of blockchain technology can support the transfer and enforcement of rights.
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No Consensus in the Ripple Network
A technical analysis of Ripple’s protocol reveals that it ensures neither safety nor liveness under the stated assumptions.
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Seminar on Trusted Computing and Secure Protocols
The Cryptology and Data Security Research Group organizes a seminar on Trusted Computing and Secure Protocols, to be held at Uni Bern on September 8, 2020, 10:15-12:00.
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Consensus Beyond Thresholds
Congratulations to Orestis Alpos to the paper on Consensus Beyond Thresholds at SRDS 2020 in September. Due to the pandemic, the conference takes place online and nobody travels to Shanghai, unfortunately.
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Course Overview
After starting teaching in cryptology and data security during 2019 and 2020, we are currently planning the following course offerings.
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Seminar on Privacy and Data Protection
The seminar has been postponed due to the Coronavirus situation
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Christian Cachin elected ACM Fellow
Every year, the Association for Computing Machinery (ACM) recognizes the top 1% of its members for their outstanding accomplishments in computing and information technology.
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Giorgia Azzurra Marson joins the group
In December 2019, Giorgia Azzurra Marson has joined the team as a postdoctoral researcher.
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Jovana Mićić and Alex Pellegrini join the group
At the start of September 2019, Jovana Mićić and Alex Pellegrini have joined the team.
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Swiss Crypto Day in Bern
The first edition of the Swiss Crypto Day takes place on 5 September 2019 and is hosted by the crypto group at the University of Bern. It is an informal event to promote research in cryptology in Switzerland and will take place at irregular intervals.
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Ignacio Amores Sesar joins the team
As the third Ph.D. student in the group Ignacio Amores Sesar joins the team. Originally from Spain, he has a background in mathematics and most recently completed his M.Sc. at the University of Copenhagen in Denmark. Welcome!
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Trusted Computing meets Blockchain - Paper at SRDS 2019
Our paper Trusted Computing meets Blockchain: Rollback Attacks and a Solution for Hyperledger Fabric describes how to run smart contracts on Hyperledger Fabric within an Intel SGX trusted execution environment. It will appear at IEEE SRDS 2019 in Lyon this October. You’ll find the code on github in a Hyperledger Lab.
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Crypto@Bern blog
Started a new blog: Crypto@Bern
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Orestis Alpos joins the team
Welcome Orestis Alpos! He joins from Greece, where he studied Electrical Engineering and Computer Science at NTUA and graduated with a thesis topic linking computer security with machine learning.
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Luca Zanolini joins the team
Welcome Luca Zanolini! He has a degree in mathematics and joins the Cryptology and Data Security Research Group this month from a blockchain startup.
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Website goes live
The website of the Cryptology and Data Security Research Group is live at crypto.unibe.ch, thanks to Jekyll, SCSS, and git.
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