Incentive Analysis of Bitcoin-NG, Revisited

Bitcoin-NG is among the first blockchain protocols to approach the near-optimal throughput by decoupling blockchain operation into two planes: leader election and transaction serialization. Its decoupling idea has inspired a new generation of high-performance blockchain protocols. However, the existing incentive analysis of Bitcoin-NG has several limitations. First, the impact of network capacity is ignored. Second, an integrated incentive analysis that jointly considers both key blocks and microblocks is still missing. In this paper, we aim to address the two limitations. First, we propose a new incentive analysis that takes the network capacity into account, showing that Bitcoin-NG can achieve better incentive compatibility against the microblock mining attack under limited network capacity. Second, we leverage a Markov decision process (MDP) to jointly analyze the incentive of both key blocks and microblocks, showing that Bitcoin-NG is as secure as Bitcoin when the adversary controls less than 35% of the computation power. We hope that our in-depth incentive analysis for Bitcoin-NG can shed some light on the mechanism design and incentive analysis of next-generation blockchain protocols.