Consensus latency of PoW blockchains
Ke Wang, Hyong S. Kim · 2022
We analyze the consensus latency of Proof of Work (PoW) blockchains. A block reaches consensus if it is included in every miner’s longest chain. We define consensus latency in this paper as the duration from when a block is mined to when that block first reaches consensus. Understanding consensus latency helps us reason about when to confirm blocks for a series of confirmation rules. We find that blocks could reach consensus fast in practical scenarios. For instance, in a propagation network with maximum network delay delta, a block could reach consensus in about 1.3 deltas on average. Contrary to common expectations, average consensus latency even decreases when mining becomes easier. We establish an analytical model to understand the relation between consensus latency and various system parameters in various scenarios. We also build a blockchain simulator to validate the accuracy of our analysis. Our estimation closely tracks the simulation results.