发表机构
University of Colorado, Boulder; University of Colorado Denver（科罗拉多大学博尔德分校; 科罗拉多大学丹佛分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对PoW区块链的51%攻击，提出结合早期算力监控预警与检查点限制链重组深度的两层防御，经蒙特卡洛模拟验证可有效降低攻击影响。
AI 中文摘要
51%攻击仍然是工作量证明（PoW）区块链中一个重大的安全问题，其中不断增加的哈希算力集中度可能造成恶意多数控制风险，并使对抗性链重组成为可能。本文提出了一种结合早期哈希算力监控与基于检查点的缓解措施的两层防御机制。第一层监控挖矿算力集中度，并在达到关键多数控制阈值之前提供早期预警。第二层利用检查点机制限制可接受的链重组深度。采用蒙特卡洛模拟在不同攻击场景下评估这两种机制。在1000次模拟运行中，45%的预警阈值在达到建模的50%关键阈值之前，提供了平均10.531分钟的预警至临界提前时间。在选定的检查点深度N=6时，约63.68%的模拟重组尝试被拒绝，而平均重组深度结果从7.948个区块降至1.634个区块，约减少79.4%。结果表明，早期检测与基于检查点的缓解措施提供了互补机制，可在评估条件下降低51%攻击的潜在影响。
英文摘要
The 51% attack remains one of the significant security concern in Proof-of-Work (PoW) blockchains, where increasing hash-power concentration can create a malicious majority-control risk and enable adversarial chain reorganization. This paper proposes a two-layer defense that combines early hash-power monitoring with checkpoint-based mitigation. The first layer monitors mining-power concentration and provides an early warning before the critical majority-control threshold is reached. The second layer uses checkpointing to restrict the depth of accepted chain reorganizations. Monte Carlo simulations are used to evaluate both mechanisms under different attack scenarios. Across 1,000 simulation runs, a 45% warning threshold provided a mean warning-to-critical lead time of 10.531 minutes before the modeled 50% critical threshold was reached. At the selected checkpoint depth of N = 6, approximately 63.68% of simulated reorganization attempts were rejected, while the mean reorganization-depth outcome decreased from 7.948 to 1.634 blocks, representing an approximately 79.4% reduction. The results demonstrate that early detection and checkpoint-based mitigation provide complementary mechanisms for reducing the potential impact of 51% attacks under the evaluated conditions.
