Clear DefinitionsDelegated Byzantine Fault Tolerance
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Pronunciation
[del-uh-gey-tid biz-uhn-teen fawlt tol-er-uhns]
Analogy
Imagine a large country needing to make important decisions. Instead of everyone in the country participating in every complex BFT-style debate and vote, the citizens elect a smaller parliament (the delegates). This parliament then uses a BFT protocol amongst themselves to make decisions. This is faster and more efficient than involving everyone, but relies on the parliament members being honest and competent.
Definition
A Byzantine Fault Tolerance (BFT) consensus mechanism where a limited set of nodes (delegates or validators), often elected or chosen by token holders, are responsible for executing the BFT protocol to validate transactions and reach consensus. This is a common approach in Delegated Proof-of-Stake (DPoS) systems.
Key Points Intro
Key Points
A specific type of BFT mechanism used in systems with a limited, often elected, set of consensus nodes (delegates).
Token holders typically delegate their voting power or stake to these chosen delegates.
The delegates then run a BFT protocol (like a variant of PBFT) among themselves to agree on blocks.
Aims for faster consensus finality and higher transaction throughput due to the smaller number of participating consensus nodes.
Example
NEO is a well-known blockchain platform that uses Delegated Byzantine Fault Tolerance (dBFT) as its consensus mechanism. NEO token holders vote for consensus nodes (bookkeepers), and these nodes then run the dBFT protocol.
Technical Deep Dive
In DBFT, once the set of delegates is chosen (e.g., through DPoS voting), these delegates engage in a multi-round communication protocol to propose, validate, and commit blocks. This usually involves a primary (speaker) proposing a block, and other delegates validating and voting on it. Consensus is reached if a supermajority (typically 2/3+1) of delegates agree. If the primary is faulty, a view change protocol can elect a new primary. The security relies on the assumption that no more than 'f' out of '3f+1' (or a similar threshold) delegates are malicious or faulty.
Security Warning
The security of DBFT depends on the honesty and operational security of the elected delegates. If a sufficient number of delegates collude or are compromised, they can potentially censor transactions or halt the network. The mechanism for selecting delegates and ensuring their accountability is crucial.
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