Federated Byzantine Agreement

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Pronunciation

[fed-uh-ray-tid byz-an-teen uh-gree-muhnt]

Analogy

FBA is like a social network where each person trusts a small circle of friends; global emerges from overlapping trust circles.

Definition

A model in which each selects its own slices—subsets of trusted peers—enabling decentralized agreement without global membership lists.

Key Points Intro

FBA’s arises from these properties:

Key Points

Quorum slice: Each node defines which peers it trusts.

Quorum: A set of nodes containing at least one slice for each member.

Decentralized control: No central authority defines quorums.

Fault tolerance: Tolerates Byzantine behavior if trust overlap is sufficient.

Example

The Stellar network uses the (SCP), an FBA implementation where organizations choose trusted sets to reach on transactions.

Technical Deep Dive

Nodes advertise slices. proceeds via nomination (proposing values) and federated voting (accept/confirm). A accepts a value when enough of its slice votes affirmatively; it confirms when enough of its slice confirms. Overlapping slices ensure global consistency.

Security Warning

Poorly configured slices can lead to partitioning or safety failures; nodes must choose slices with sufficient overlap.

Caveat

Security depends on careful slice configuration; dynamic membership changes are complex to manage.

Related Terms

Stellar Consensus Protocol

Byzantine Fault Tolerance

SCP

Blockchain & Cryptocurrency Glossary

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