Deutsche Forschungsgemeinschaft
Prof. Hans P. Reiser
Distributed Ledger Technologies (DLTs), often referred to as blockchains, enable the realisation of reliable and attack-resilient services without a central infrastructure. This offers benefits to a large variety of applications, such as smart contracts, industrial supply chains and distributed storage services. However, the widely used proof-of-work mechanisms for DLTs suffer from high latencies of operations and enormous energy costs. Byzantine fault-tolerant (BFT) consensus protocols prove to be a potentially energy-efficient alternative to proof-of-work. However, current BFT protocols also present challenges that still limit their practical use in production systems.
This research project addresses these challenges by
The topic of scalability aims at finding practical solutions that take into account challenges such as recovery from major outages or upgrades, as well as reconfigurations
at runtime. We also want to design a resilient communication layer that decouples the choice of a suitable communication topology from the actual BFT consensus protocol and thus reduces its complexity. This should be supported by the use of trusted hardware components. In addition, we want to investigate combinations of these concepts with suitable cryptographic primitives to further improve scalability.
Using systematic modelling techniques, we want to be able to analyse the efficiency of scalable, complex BFT protocols (for example, in terms of throughput and latency of operations), already before deploying them in a real environment, based on knowledge of system size, computational power of nodes, and basic characteristics of the
communication links. We also want to investigate robust countermeasures that help defending against targeted attacks in large-scale blockchain systems.
The third objective is to support the systematic and valid implementation in a practical system, structured into a constructive, modular approach, in which a validatable BFT protocol is assembled based on smaller, validatable building blocks; the incorporation of automated test procedures based on a heuristic algorithm which makes the complex search space of misbehaviour in BFT systems more manageable; and a tool for automated deployment with accompanying benchmarking and stress testing in large-scale DLTs.
C. Berger, L. Rodrigues, H. P. Reiser, V. Cogo and A. Bessani, "Chasing Lightspeed Consensus: Fast Wide-Area Byzantine Replication with Mercury" in The 25th ACM/IFIP International Middleware Conference (MIDDLEWARE 24) , New York, NY, USA: Association for Computing Machinery, 2024.
C. Berger, S. B. Toumia and H. P. Reiser, "Exploring Scalability of BFT Blockchain Protocols through Network Simulations" , Formal Aspects of Computing , 2024. Association for Computing Machinery.
DOI: 10.1145/3689343
C. Berger, S. B. Toumia and H. P. Reiser, "Scalable Performance Evaluation of Byzantine Fault-Tolerant Systems Using Network Simulation" in 2023 IEEE 28th Pacific Rim International Symposium on Dependable Computing (PRDC) , 2023. pp. 180-190.
C. Berger, S. Schwarz-Rüsch, A. Vogel, K. Bleeke, L. Jehl, H. P. Reiser and R. Kapitza, "Sok: Scalability techniques for BFT consensus" in 2023 IEEE International Conference on Blockchain and Cryptocurrency (ICBC) , 2023. pp. 1-18.
S. Ben Toumia, C. Berger and H. P. Reiser, "Evaluating Blockchain Application Requirements and their Satisfaction in Hyperledger Fabric" in Proc. of the 22nd Int. Conf. on Distributed Applications and Interoperable Systems (DAIS) , 2022.
C. Berger, H. P. Reiser and A. Bessani, "Making Reads in BFT State Machine Replication Fast, Linearizable, and Live" in Proc. of the 40th IEEE International Symposium on Reliable Distributed Systems (SRDS) , 2021.
