Nakamoto共识中验证前挖矿的安全极限

中文摘要 AI 辅助

验证前挖矿允许矿工在完成对新接收区块的有效性检查之前扩展该区块，从而在争夺下一个区块奖励的竞赛中获得领先优势。然而，这种领先优势伴随着安全风险：拒绝一个无效区块也会丢弃建立在其上的诚实工作，当验证被视为瞬时完成时，这种影响会被忽略。我们在一个具有有界网络延迟和独立于处理负载的验证时间界限的Nakamoto共识模型中量化了这种风险。我们建立了对手挖矿能力的显式阈值，低于该阈值时，诚实矿工的完全验证链继续增长，并在任何固定观察期内以高概率就稳定历史达成一致。我们还构造了一种攻击，反复将诚实挖矿引向无效分支。当对手在允许的验证时间内平均产生超过一个区块时，该攻击最终可以在任何固定的初始确认深度移除目标区块。结合普通的私有挖矿，这种攻击在完全去中心化机制中产生匹配的渐近界限，其中每个诚实矿工具有可忽略的挖矿能力。结果表明，验证延迟如何限制验证前挖矿的安全性，超出了网络延迟所施加的约束。

英文摘要

Mining before validation allows miners to extend a newly received block before completing its validity checks, giving them a head start in the race for the next block reward. This head start, however, comes with a security risk: rejecting one invalid block also discards the honest work built on it, an effect missed when validation is treated as instantaneous. We quantify this risk in a model of Nakamoto consensus with bounded network delay and a validation-time bound independent of processing load. We establish an explicit threshold on adversarial mining power below which honest miners' fully validated chains continue to grow and agree on a stable history with high probability over any fixed observation period. We also construct an attack that repeatedly draws honest mining onto invalid branches. When the adversary produces more than one block on average during the allowed validation time, the attack can eventually remove a target block at any fixed initial confirmation depth. Combined with ordinary private mining, this attack yields a matching asymptotic bound in the fully decentralized regime, where each honest miner has negligible mining power. The results show how validation latency limits the security of mining before validation, beyond the constraint imposed by network delay.

发表机构

• Huazhong University of Science and Technology（华中科技大学）
• University of Warwick（华威大学）

机构由 AI 辅助整理，请以论文原文为准。