Martin Florian

Federated Byzantine Agreement

I investigate a novel approach to consensus protocols that is ecologically sustainable and rigorously secure while enabling more decentralization than your typical permissioned system. It's kind of like bootstrapping consensus from a web of trust.

Federated Byzantine Agreement Systems (FBASs)1 are a fascinating new paradigm in the context of consensus protocols. FBASs can be used for bootstrapping blockchain systems that are energy-efficient and secure while supporting decentralization and open membership. The FBAS model could play a decisive role for redirecting the demand for decentralized systems like Bitcoin towards a vastly more sustainable technological base. Every member of an FBAS is free to configure with whom it requires agreement, with FBASs emerging as the sum of all individual configurations. Intuitively, FBAS-based protocols can enable secure bottom-up consensus through leveraging the individual knowledge and relationships of each participating entity. The FBAS paradigm powers the Stellar Consensus Protocol (SCP) used by the Stellar and MobileCoin networks.

An example FBAS.

I'm especially interested in the properties that specific FBAS instances must exhibit in order to function as a safe foundation for consensus protocols and blockchain networks, and how the preconditions to these properties influence the decentrality and openness of resulting systems. We've developed a pretty useful analysis methodology for FBASs here, also formally deriving some limitations to "decentrality". Our analysis framework fbas_analyzer is in production use at, the monitoring service for the Stellar network. We also use our framework (in-browser!) in websites like these.

Output: (among others)

Funding: Weizenbaum, DFG2

1 What I'm talking about here is perhaps better described as Asymmetric Quorum Systems (AQSs). "FBAS" is the original term, however, as coined by David Mazières, and it seems to be the more recognizable one.

2 My project proposal was accepted in December 2021. However, at the time of writing, we haven't yet used any of the granted funds.