Numerous methods have been proposed for suppressing intentional forks by attackers in blockchain systems. Among these, last-generated rules, which select the latest chain among chains in a tie, are effective methods that do not require significant changes to the blockchain protocol. However, existing methods either require a trusted third party or rely on timestamps that attackers can manipulate which makes applying a last-generated rule to existing systems such as Bitcoin challenging. To address these issues, we propose a last-generated rule that can be easily applied to existing proof of work blockchain systems. Our method uses partial proof of work, which does not function as a block, as a time standard with finer granularity. Only weak synchronization, which is already met by existing systems, is required for effective functioning. We evaluated the proposed method through a detailed analysis that is lacking in existing works. In networks that adopt our method, the proportion of the attacker hashrate necessary for selfish mining was approximately 0.31479 or higher, regardless of the block propagation capability of the attacker. Furthermore, we demonstrated through extended selfish mining that the impact of Match against pre-generated block, which is a concern in all last-generated rules, can be mitigated with appropriate parameter settings.

翻译：在区块链系统中，针对攻击者蓄意制造分叉的抑制方法已有诸多研究。其中，选择平局链中最新区块的"最后生成规则"是一种无需对区块链协议进行重大修改的有效方法。然而现有方法要么需要可信第三方，要么依赖攻击者可篡改的时间戳，这使得将最后生成规则应用于比特币等现有系统面临挑战。针对这些问题，我们提出一种可便捷应用于现有工作量证明区块链系统的最后生成规则。该方法采用不构成区块的部分工作量证明作为具有更细粒度的时序标准，且仅需现有系统已满足的弱同步条件即可有效运行。我们通过现有研究缺乏的详细分析对提出方法进行了评估。在采用本方法的网络中，无论攻击者具有何种区块传播能力，其实现自私挖矿所需的算力占比需达约0.31479或更高。此外，通过扩展自私挖矿分析证明，所有最后生成规则共同面临的"匹配预生成区块"问题，可通过合理参数设置得到缓解。