What is Casper in a Nutshell / Casper 懶人包

以下重點整理摘自 2017 Blockchain Tech Seminar @ NCCU

Following notes are taken from 2017 Blockchain Tech Seminar @ NCCU

<特點 Features>

1. 以保證金為設計的權益證明演算法 (PoS)，高度最終安全，低成本的共識演算法。A proof of stake algorithm with validators.
2. 基於拜占庭容錯 (BFT)：拿到超過 2/3 的票數 。 BFT-style proof of stake.
3. 加入懲罰機制。 Adding punishment mechanism.
4. 當區塊鏈收斂成一條鏈 -> 賺錢。 Validators get payment when  blockchain converge .

<PoW vs. PoS>

Proof of Work： 

• 耗費大量電力 。Consume large quantities of electricity.
• 礦池集中問題 。Issues of centralization risk to pools.
• 沒有提供經濟確認性 (Economic Finality)。Without economic finality.
• 礦工不需成本 (只要成為最長的鏈)就能撤銷過去紀錄 。Miners can revoke records without cost if he can be the longest chain.

經濟確認性 (Economic Finality)：一個區塊被認為已成定局，假設在同高度上，存在有誤的另一方並課以 X 等量的罰金。 

Economic Finality: Economic finality is the idea that once a block is finalize, then the only way that at any point in the future the canonical history will contain a conflicting block is if a large number of people are willing to burn very large amounts of money.

Proof of Stake：

• 多回合的共識形成 (Checking Point -> Final Checking Point)。Multi-round consensus algorithm.
• 虛擬挖礦 (Voting會與放置的保證金成正比)。Virtual Mining.
• 提供經濟確認性 (保證金設計)。Provide Economic Finality.
• 節能。No need to consume large quantities of electricity.