什麼是 Zk-Rollups？ Layer-2 可擴展性技術解析

Original title: What is Zk summary? Layer 2 Scalability Technologies

Summary

• Blockchain’s low scalability results in slowdowns, transaction fees Improvement and poor user experience. This problem can potentially be fixed with corresponding solutions such as Layer 1 (e.g. sharding) and Layer 2 (e.g. rollups).
• Layer 1 solutions aim to upgrade the blockchain itself, while Layer 2 solutions create a framework based on the existing chain.
• Rollups are a popular Layer 2 solution, they package transactions off-chain for faster computation.
• Zk-rollups is a rollup implementation using zero-knowledge proofs.
• Zero-knowledge proof allows verification without revealing the underlying data, ensuring transaction privacy and security.

The race for blockchain scalability

With the widespread adoption of cryptocurrencies, solving the scalability problem of blockchain networks has become critical. It's important. A crowded blockchain can lead to slower speeds and higher transaction fees. To solve this problem, we have two main frameworks: Layer 1 and Layer 2 solutions.

• Layer 1 Solutions: These solutions directly improve the infrastructure of the blockchain to enable the entire system to achieve higher throughput. Sharding is a typical example. By dividing the blockchain into different blocks, it increases the capacity of the system and allows transactions to be processed simultaneously.
• Layer 2 solutions: These solutions run on top of the underlying blockchain. In Layer 2, transactions are processed off-chain and submitted together to the underlying chain. Key technologies include state channels, sidechains, and rollups. Zk-rollups are a form of rollups that utilize zero-knowledge proofs.

What are Zk-Rollups?

To understand Zk-rollups, it is important to understand rollups and zero-knowledge proofs.

What are rollups?

Rollups allow blockchains to package transaction data together and process it off-chain. After processing, the final result will be submitted to the underlying chain. Processing so many transactions simultaneously eliminates the potential for blockchain bloat and enables faster, cheaper computation. Rollups are divided into two categories: Optimistic and Zk-rollups.

• Optimistic rollups: Optimistic rollups operate under the assumption that all transactions it packages are legitimate. Before these transactions are committed to the blockchain, they go through a waiting period. During this waiting period, the network raises objections to question suspicious transactions. Optimism, Arbitrum and opBNB are examples of Optimistic rollups.
• Zk-rollups: Unlike Optimistic rollups, zk-rollups verify each transaction through zero-knowledge proof. Although more complex to implement, zk-rollups are designed to bypass the dispute resolution period seen in optical rollups, theoretically processing transactions faster.

Now, let’s understand zero-knowledge proofs.

What is zero-knowledge proof?

Zero-knowledge proof (ZKP) is a cryptographic tool that allows one party (the prover) to prove to another party (the verifier) ​​that a certain statement is true without revealing anything about the statement. details.

ZKP must have three characteristics:

• Completeness: If a statement is true and both parties are true, a proof will always confirm its authenticity.
• Reliability: An untruthful prover should not be able to convince an honest verifier that the false statement is valid in rare circumstances.
• Zero knowledge: the most defining characteristic. At the end of the process, the verifier only learns about the validity of the statement, but not about its content.

So, how does ZKP work? The method can be divided into three steps:

• Witness: In the first stage, the prover provides a secret message, or "witness" to the verifier. The idea here is to prove to the verifier that the prover has access to specific data without explicitly mentioning it. A testimony establishes a set of questions about the information that only a legitimate attestor can answer.
• Challenge: In this phase, the verifier issues a challenge to the prover by selecting a random question from the set.
• Response: The prover successfully answered the verifier's question to prove their trustworthiness.

Now we know what rollups and ZKP are. Let's put it all together and understand how zk-rollups work.

How do Zk-Rollups work?

Zk-rollups has two core components:

• Smart contracts on the chain: Smart contracts define the operating rules of the zk-rollup protocol. It includes main contract and verification contract. The main contract stores rollup blocks, tracks deposits and makes important updates. The verification contract verifies the generated ZKP.
• Off-chain virtual machines: These machines are responsible for handling transaction execution in L2. Off-chain virtual machines operate independently of the Ethereum main chain.

Zk-rollups are closely intertwined with the Ethereum blockchain, albeit on a unique level. They don’t flood Ethereum with the details of every transaction. Instead, they cleverly provide packaging digests, ensuring that the underlying chain remains clean and efficient.

Pros and cons of using Zk-Rollups

So, what are the benefits of using zk-rollups? let's see.

Advantages of zk-rollups

• Increased throughput: zk-rollups moves transaction execution from the underlying chain to a more efficient computing environment. Since transactions are not processed one-by-one on the chain, it increases overall throughput.
• Reduced congestion: By reducing blockchain bloat, zk-rollups help enable efficient Layer 1 operations. Additionally, full nodes only need to store zero-knowledge proofs instead of the entire data.
• Reduced fees: zk-rollups help reduce overall fees due to reduced congestion.
• Safety measures: zk-rollups include security measures that allow users to withdraw funds in the event of problems with the rollup network, which is a clear advantage compared to sidechains, which can compromise funds during network failures.
• Faster transaction challenge period: Using zk-rollups, you only need to verify the validity proof within the rollups to speed up the transaction challenge period.

Disadvantages of zk-rollups

• 複雜性：zk-rollups 的最大缺點是它們的內在複雜性。它們執行起來比optimistic rollups 更為複雜。
• 受底層鏈限制：儘管它們效率高，zk-rollups 仍受到底層基礎層的限制。
• 流動性片段化：任何 Layer 2 都會導致生態系中流動性的分散。底層鏈協定中流動性較淺可能導致潛在問題。

OptimisticRollupsvsZk-Rollups

總結

#可擴展性經常被吹捧為區塊鏈技術的「聖杯」。如果系統不能運作得最佳，那就沒有使用它的意義。 Rollups，包括 optimistic 和 zk，為這個長期存在的問題提供了一個優雅的解決方案。 Zk-Rollups 以其獨特的方法承諾更快的速度、更少的流量和強大的安全性。是的，它們有複雜性，但它們的潛力是巨大的。對於任何關心數位貨幣未來的人來說，了解 zk-rollups 是必不可少的。隨著我們不斷推動更好的區塊鏈效能，現在是時候熟悉 zk-rollups 及其對未來的承諾了。

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