MEV：區塊鏈隱私的隱藏威脅

中本聰是個天才，但在隱私方面，他卻敞開了大門。現在，禿鷹正在大快朵頤。

Satoshi Nakamoto was a genius, but when it comes to privacy, he left the door wide open. Now, the vultures are feasting. The original blockchain and its many descendants are transparent, immutable, and decentralized. That might sound like everything you ever wanted from a financial system, but you’re wrong.

中本聰是個天才，但在隱私方面，他卻敞開了大門。現在，禿鷹正在大快朵頤。最初的區塊鏈及其許多後代都是透明的、不可變的和去中心化的。這聽起來可能像是您想要從金融系統中獲得的一切，但您錯了。

Privacy is a vital component of any secure financial system. There’s an inherent contradiction between blockchain technology and privacy. The desire for privacy is essential, and the right to be forgotten is enshrined in law. Still, blockchain technology violates this principle with its very existence because it’s an infusible, yet permanent and public, data ledger.

隱私是任何安全金融系統的重要組成部分。區塊鏈技術與隱私之間存在固有的矛盾。對隱私的渴望是至關重要的，被遺忘的權利是法律規定的。儘管如此，區塊鏈技術的存在仍然違反了這個原則，因為它是一個不可熔的、永久的、公共的資料分類帳。

Maybe you don’t care because the only information that anyone can see is a string of random letters and numbers, however, this has real-life implications for transactions on the chain.

也許您不在乎，因為任何人都可以看到的唯一資訊是一串隨機字母和數字，但是，這對鏈上交易具有現實意義。

Consider a potential example: You go to Uniswap to buy a token, place your order, execute…and receive significantly less of the token than you expected. You check the pair’s order history and find that a large buy was made just before yours, pushing the price up, with a hefty sell following after your order went through. You’ve just been “front-run,” and probably not for the first time. 

考慮一個可能的例子：您去 Uniswap 購買代幣，下訂單，執行…並收到比您預期少得多的代幣。您檢查了該貨幣對的訂單歷史記錄，發現在您的訂單之前進行了大量買入，推高了價格，而在您的訂單完成後又進行了大量賣出。您剛剛“搶先”，而且可能不是第一次了。

Front-run? You might think: “I was an ace runner in school; no one’s beating me!” Let’s take a step back and explain what front-running is.

搶先跑？你可能會想：“我在學校是一名優秀的跑步運動員；我是一名優秀的跑步運動員。”沒人打我！讓我們退一步解釋一下什麼是搶先交易。

What is MEV?

什麼是MEV？

Maximal extractable value (MEV) refers to the maximum value a blockchain miner or validator can make by including, excluding or changing the order of transactions during the block production process.

最大可提取價值（MEV）是指區塊鏈礦工或驗證者在區塊生產過程中透過包含、排除或更改交易順序可以賺取的最大值。

Blockchain networks are immutable ledgers secured by a decentralized network of nodes known as “block producers.” In proof-of-work blockchains, this means miners. For proof-of-stake networks, this refers to validators. The block producers are responsible for regularly aggregating pending transactions into blocks, which are then validated by the entire network and appended to the global ledger. While blockchain networks ensure all transactions are valid (e.g. no double-spends) and new blocks of transactions are continually produced, there isn’t a guarantee that transactions will be ordered as they were submitted to the blockchain.

區塊鏈網路是不可變的分類賬，由稱為「區塊生產者」的去中心化節點網路保護。在工作量證明區塊鏈中，這意味著礦工。對於權益證明網絡，這是指驗證者。區塊生產者負責定期將待處理的交易聚合到區塊中，然後由整個網路驗證並附加到全局分類帳中。雖然區塊鏈網路確保所有交易都是有效的（例如沒有雙花）並且不斷產生新的交易區塊，但不能保證交易在提交到區塊鏈時會被排序。

As each block can only contain a limited number of transactions, block producers have complete autonomy in selecting which pending transactions are in the mempool. In this memory pool, block producers store unconfirmed transactions offchain, which they will include in their block. As a result, block producers have full autonomy to engage in rent-seeking behavior by extracting MEV with impunity. For instance, the cumulative value of MEV extracted on Ethereum reached $78 million in early 2021, which then shot up to $554 million by the end of the year. MEV extracted on Ethereum now stands at over $600 million.

由於每個區塊只能包含有限數量的交易，因此區塊生產者在選擇記憶體池中哪些待處理交易方面擁有完全的自主權。在這個記憶體池中，區塊生產者將未確認的交易儲存在鏈下，並將其包含在區塊中。因此，區塊生產者擁有完全的自主權，可以透過提取 MEV 來從事尋租行為而不受懲罰。例如，2021 年初，以太坊上提取的 MEV 累計價值達到 7,800 萬美元，到年底飆升至 5.54 億美元。目前在以太坊上提取的 MEV 價值超過 6 億美元。

Problems and solutions around MEV 

MEV相關問題及解決方案

Thankfully, the last few years have seen the development of various methods to mitigate the problem of MEV. These fall into two buckets: new transaction ordering protocols and modifications to existing protocols that reduce the scope for manipulation.

值得慶幸的是，過去幾年出現了各種方法來緩解 MEV 問題。這些分為兩類：新的交易排序協議和現有協議的修改，以減少操作範圍。

One solution that takes the former approach is Fair Sequencing Services (FSS), which ensures that transactions are ordered relatively to reduce opportunities for front-running or reordering by miners and validators. One example is Chainlink’s Fair Sequencing Service, which uses decentralized oracles to maintain fair transaction ordering. Another such protocol is First-In-First-Out (FIFO), which processes transactions as they arrive at the mempool. This method offers a straightforward solution to maintain order integrity, minimizing the chance for miners to manipulate transaction sequences for MEV.

採用前一種方法的解決方案是公平排序服務（FSS），它確保交易相對排序，以減少礦工和驗證者搶先交易或重新排序的機會。一個例子是 Chainlink 的公平排序服務，它使用去中心化的預言機來維護公平的交易排序。另一個這樣的協議是先進先出（FIFO），它在交易到達記憶體池時對其進行處理。這種方法提供了一種簡單的解決方案來維護訂單完整性，最大限度地減少礦工操縱 MEV 交易序列的機會。

Recent: ‘Unlucky’ MEV bot takes out huge $12M loan just to make $20 in profit

最近：「不幸的」MEV 機器人借了 1200 萬美元的巨額貸款，只是為了賺取 20 美元的利潤

These approaches have a common goal: to create a fairer and more secure transaction ordering system and reduce the potential for manipulation. This objective is essential for building the trust necessary for decentralized ecosystems to go mainstream.

這些方法有一個共同的目標：創造一個更公平、更安全的交易排序系統並減少操縱的可能性。這個目標對於建立去中心化生態系統走向主流所需的信任至關重要。

MEV mitigation approach

MEV緩解方法

The block producers rely on visible transaction data to manipulate transactions for profit. Privacy protocols solve the issue, although the primary function has never been eliminating MEV.

區塊生產者依靠可見的交易數據來操縱交易以獲取利潤。隱私協議解決了這個問題，儘管主要功能從來不是消除 MEV。

Ring Confidential Transactions (RingCT) obfuscates vital transaction details, including the transaction amount, sender and recipient. RingCT prevents miners from determining which transactions might be lucrative to manipulate, reorder or front-run. If specific details of individual transactions are made invisible, MEV extraction becomes virtually impossible, as miners are left blind to potential arbitrage or front-running opportunities.

環形機密交易 (RingCT) 會混淆重要的交易詳細信息，包括交易金額、發送方和接收方。 RingCT 可以防止礦工確定哪些交易可能透過操縱、重新排序或搶先交易而獲利。如果單筆交易的具體細節不可見，MEV 提取幾乎變得不可能，因為礦工對潛在的套利或搶先交易機會視而不見。

Likewise, stealth addresses are another powerful privacy tool to mitigate MEV. They generate unique, one-time addresses for each transaction, hiding the recipient’s identity. Since the addresses are untraceable, miners cannot focus on high-value transactions, removing the incentive to prioritize or reorder them for personal gain.

同樣，隱形位址是緩解 MEV 的另一個強大的隱私工具。它們為每筆交易產生唯一的一次性地址，隱藏收件人的身分。由於地址無法追踪，礦工無法專注於高價值交易，從而消除了為了個人利益而對它們進行優先排序或重新排序的動機。

MEV relies on the ability of miners or validators to see transaction data to manipulate transaction order or inclusion. Privacy-centric design targets miners

MEV 依賴礦工或驗證者查看交易資料來操縱交易順序或包含的能力。以隱私為中心的設計針對礦工