What are the privacy solutions on Ethereum?

好的，咱们来聊聊以太坊上的隐私问题和对应的解决方案。

以太坊这地方，默认情况下就像一个“透明的玻璃房子”。你做了什么交易、账户里有多少钱、跟谁有过往来，只要有你的地址，任何人都能在 Etherscan 这样的浏览器上查得一清二楚。这在很多场景下是很酷的，完全公开透明。但如果你想买个东西不让全世界知道，或者不希望别人根据你的钱包余额来判断你的身家，这就很尴尬了。

所以，为了解决这个问题，社区里的大佬们想出了各种各样的方法。我把它们分成几类，这样更好理解。

## 1. "Mix it up, nobody can find you" - Mixers

This is the most direct and well-known method.

• How it works: Imagine a giant "communal piggy bank" or "mixing pot." Many people throw their funds (e.g., 1 ETH) into this pot. After some time, you withdraw 1 ETH from this pot to a brand-new address. Because the pot contains funds from hundreds or thousands of people, it becomes very difficult for outside observers to trace the connection between the ETH you withdrew and the ETH you initially deposited. This effectively severs the chain of fund flow.

• Typical Representative: Tornado Cash

  • Tornado Cash is the most famous implementation of this "mixing pot." It utilizes a technology called "zero-knowledge proofs," allowing you to prove to the system that "I did indeed deposit funds" when withdrawing, without having to reveal the specific deposit.
  • Pros: Simple, direct, and effectively severs the link for individual transactions.
  • Cons: Because of its effectiveness, it has also been used by illicit actors for money laundering, leading to strong regulatory crackdowns and legal risks associated with its use today. Furthermore, it primarily addresses "transfers" and is ineffective for more complex smart contract interactions.

## 2. "Let's chat in a private room next door" - Privacy Layer 2 Solutions

The mainnet (Layer 1) is too public, so we move our activities to a "private" Layer 2 network, only interacting with the mainnet when necessary.

• How it works: You first deposit your funds from the public Ethereum mainnet into a privacy-enabled Layer 2 network. Within this Layer 2 network, all your transactions and transfers are encrypted, so others cannot see the details. You can interact freely with others there. Finally, when you need to withdraw funds back to the mainnet, you follow a withdrawal process. Throughout this entire process, others only know that you "deposited funds" and "withdrew funds," but what happened in between remains completely unknown to them.

• Typical Representatives:

  • Aztec Network: This is currently a leading privacy Layer 2 solution. It's a network based on ZK-Rollup technology. In Aztec, transactions are encrypted by default. You can think of it as an "encrypted version of Ethereum," where you can perform private transfers and DeFi operations. It bundles a large number of users' private transactions, then generates a "zero-knowledge proof" and submits it to the Ethereum mainnet, proving to the mainnet that "all these transactions we performed on the Layer 2 network are valid," without revealing any transaction details whatsoever.
  • StarkNet / zkSync etc. Generic ZK-Rollups: While their primary goal isn't privacy, the ZK technology (zero-knowledge proofs) they employ inherently possesses the potential to enable privacy. In the future, more privacy-focused dApps may emerge on these platforms, allowing users to perform selective private operations.

## 3. "Here's a disposable alias" - Stealth Addresses

This solution primarily protects the privacy of the "recipient."

• How it works: Imagine you don't want others to know your home address, but you still want to receive packages. So, you use a package collection point and generate a unique pickup code each time. Others deliver the package to the collection point, write down your pickup code, and only you know that this code corresponds to you. Stealth addresses work similarly. When you need to receive funds, you can generate a one-time, brand-new Ethereum address for the sender. The sender sends funds to this new address, and only you can access these funds, but from the blockchain, others cannot discern any connection between this new address and your identity. This prevents everyone from sending money to your single, public address, thereby exposing your total assets.

• Current Progress: Vitalik Buterin (V God) himself is actively promoting this solution. Through technologies like Account Abstraction (ERC-4337), stealth addresses are becoming increasingly practical and may become a fundamental feature in many wallets in the future.

## Summary

Overall, privacy on Ethereum is by no means a false proposition; rather, it's a rapidly developing field. There isn't a "perfect" solution yet, and different technologies are suited for different scenarios. For the average user, the most likely features to become widespread in the future are wallet-native "stealth address" functionalities, and using privacy Layer 2 networks like Aztec for complex private operations when needed.