区块链论文2（改进的PoW共识机制）

文章来源
https://github.com/baozjian/Top-Blockchain-paper.
Usenix Security A
2019
StrongChain: Transparent and Collaborative Proof-of-Work Consensus
Pawel Szalachowski, Daniel Reijsbergen, and Ivan Homoliak, SUTD; Siwei Sun, IIE and DCS, CAS
论文地址
https://www.usenix.org/system/files/sec19-szalachowski.pdf.

• Abstract
  Bitcoin is the most successful cryptocurrency so far. This is mainly due to its novel consensus algorithm, which is based on proof-of-work combined with a cryptographically-protected data structure and a rewarding scheme that incentivizes nodes to participate. However, despite its unprecedented success Bitcoin suffers from many inefficiencies. For instance, Bitcoin’s consensus mechanism has been proved to be incentive-incompatible, its high reward variance causes centralization, and its hardcoded deflation raises questions about its long-term sustainability.
  比特币是迄今为止最成功的加密货币。这主要归功于其新颖的共识算法，该算法基于工作量证明与受密码保护的数据结构以及激励节点参与的奖励方案相结合。但是，尽管比特币取得了空前的成功，但它仍然存在许多效率低下的问题。例如，比特币的共识机制已被证明是不兼容激励机制的，其高回报差异导致集中化，并且它的硬编码通缩让人们对它的长期可持续性提出了质疑。
  In this work, we revise the Bitcoin consensus mechanism by proposing StrongChain, a scheme that introduces transparency and incentivizes participants to collaborate rather than to compete. The core design of our protocol is to reflect and utilize the computing power aggregated on the blockchain which is invisible and “wasted” in Bitcoin today. Introducing relatively easy, although important changes to Bitcoin’s design enables us to improve many crucial aspects of Bitcoin-like cryptocurrencies making it more secure, efficient, and profitable for participants. We thoroughly analyze our approach and we present an implementation of StrongChain. The obtained results confirm its efficiency, security, and deployability.
  在这项工作中，我们通过提出StrongChain来修改比特币共识机制，该方案引入了透明度并激励参与者进行协作而不是竞争。我们协议的核心设计是反映和利用聚集在区块链上的计算能力，而这种计算能力在当今的比特币中是不可见的和“浪费的”。尽管对比特币的设计进行了重大更改，但引入了相对容易的，尽管重要的更改，使我们能够改善类似于比特币的加密货币的许多关键方面，从而使参与者更加安全，高效和有利可图。我们彻底分析了我们的方法，并提出了StrongChain的实现。获得的结果证实了其效率，安全性和可部署性。

一、现有比特币缺陷

1、Bitcoin has been proved to be incentive-incompatible [9, 11, 39, 47].
与激励机制不相容。一些矿工选择将他们找到的解决方案保留一段时间而不是立即公布。
私自挖矿：矿工将发现的区块块保密，当公共部门的区块数量即将赶上自己保存的区块的数量时释放自己的发现的块，使得其他矿工的努力付诸东流。
某个矿工计算能力超过30%，此种攻击效率更高。
2、Another issue is that the increasing popularity of the system tends towards its centralization.
系统的日益普及使其趋向于集中化。矿工之间竞争激烈使得他们的回报差异太大，导致他们开始使用矿池来分组他们的计算能力，于是数据挖掘池成了主要算力，可能会造成滥用协议的后果。
形成矿池来分工合作，破坏了系统的去中心化的优势同时也带来了池内和池间安全隐患。
交易费用比区块奖励更高，矿工们在可用费用不高的时候避免采矿，甚至在无用的区块上挖掘导致交易的积压。
3、Besides that, unusually for a transaction system, Bitcoin is designed to favor availability over consistency.
比特币更注重可用性而不是一致性。
4、链的分叉

二、本文的解决方案

we propose StrongChain, a simple yet powerful revision of the Bitcoin consensus mechanism. Our main intuition is to design a system such that the mining process is more transparent and collaborative