In today's era of rapid digital development, blockchain technology is changing our lifestyle and business model with an unstoppable momentum. Especially in the field of cryptocurrency, security and privacy have become the most concerned issues for users. With the rise of Layer2 technology, ZK (Zero-Knowledge) zero-knowledge proof, as an innovative solution, is gradually being applied to wallet cross-Layer2 transactions. This article will explore in detail how ZK zero-knowledge proof can improve security and privacy and promote technological progress in cross-Layer2 transactions.

Before going into detail, it is necessary to understand what ZK zero-knowledge proof is. Simply put, zero-knowledge proof is a cryptographic protocol that allows one party (the prover) to prove the truth of a statement to another party (the verifier) without revealing any other information. For example, suppose you want to prove to a friend that you have enough funds to buy a new phone, you can use zero-knowledge proof to prove this without showing your bank account balance. This technology not only protects personal privacy, but also improves the security of transactions.

With the popularity of Layer2 solutions, especially on public chains such as Ethereum, the problems of transaction speed and fees are gradually being solved. Layer2 greatly reduces the congestion of transactions by conducting transactions outside the main chain. However, how to protect the privacy and financial security of users in this rapidly developing environment has become an urgent problem to be solved. ZK zero-knowledge proof just provides a perfect solution to this problem.

Imagine that when a user uses a Layer2 wallet to make a transaction, he can ensure the authenticity of the transaction without leaking any sensitive information. This scenario is not a distant dream. With ZK technology, users can conduct encrypted transactions to ensure that the transaction information is only visible to the participants, and external observers cannot know any details. This privacy protection feature provides users with an unparalleled sense of security.

In practical applications, the advantages of ZK zero-knowledge proof are not only reflected in transaction privacy, but also in its efficient verification process. Take zk-SNARK (zero-knowledge succinct non-interactive argument) as an example, it can quickly verify the legitimacy of the transaction without a lot of calculations. This means that even in the case of high-concurrency transactions, users can enjoy a smooth transaction experience. Such high efficiency undoubtedly lays the foundation for the popularization of cross-Layer2 transactions.

Furthermore, the application of ZK zero-knowledge proof can be extended to more fields, such as identity authentication and data sharing. In digital identity management, users can use zero-knowledge proof to verify their identity while protecting their personal information from being leaked. The introduction of this technology can effectively prevent security risks such as identity theft and information leakage. In the field of data sharing, companies can use ZK technology to share the authenticity and validity of data without disclosing specific data, thereby promoting in-depth business cooperation.

Of course, the popularization of ZK zero-knowledge proof is not without challenges. The complexity of the technology and the cost of implementation are the main obstacles currently faced. In addition, how to ensure compliance while ensuring privacy is also an issue that cannot be ignored. As the regulatory policies of various countries on digital currency and blockchain technology become clearer, the future development of ZK technology needs to adapt to the regulatory environment in order to better serve users.

In this process, community participation and continuous iteration of technology will play a vital role. As developers continue to explore and optimize the application scenarios of ZK technology, more and more projects will emerge, which will create a more secure and private trading environment for users. For example, some emerging decentralized finance (DeFi) projects are trying to combine ZK technology with liquidity mining to create more privacy-protected financial products. This innovation can not only attract more users to participate, but also inject new vitality into the entire industry.

In terms of personal experience, the convenience and security brought by ZK zero-knowledge proof are unmatched by other technologies. As an ordinary user, I feel an unprecedented sense of peace when using a wallet that supports ZK technology for transactions. Every transaction is like a silent conversation, which can confirm the authenticity of the transaction without worrying about the leakage of my information. It feels like being in a busy market, still able to maintain my privacy and enjoy my own space.

Looking to the future, cross-Layer2 transactions of ZK zero-knowledge proof wallets will become an important trend. With the continuous maturity of technology and the growth of user demand, more innovative applications based on ZK technology will emerge in the market. In this process, the security and privacy of users will be better protected, and it also provides strong support for the popularization of blockchain technology.

In general, ZK zero-knowledge proof, as a cutting-edge encryption technology, is bringing a new revolution to cross-Layer2 transactions. By providing efficient privacy protection and security, ZK technology not only improves the user experience, but also injects new impetus into the healthy development of the entire blockchain ecosystem. In the future, we look forward to seeing more applications based on ZK technology being implemented to create a safer and more private digital transaction environment for users. Whether it is for individual users or enterprise applications, ZK zero-knowledge proof will become an indispensable tool in the digital age. With the continuous evolution of technology and the expansion of application scenarios, I believe that ZK zero-knowledge proof will play a more important role in the future blockchain world.

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Coin Circle (120btc.COM) News: Ethereum co-founder Vitalik Buterin released a new technical document "The 20th" last night. 

Vitalik directly focused on the technical field of specific sub-problems and listed three possible situations to explain: 

 How to read Layer1 from Layer2 more easily 

 How to read Layer2 from Layer1 more easily 

 How to read Layer2 from Layer2 more easily 

At the same time, he emphasized that the above three situations all need to be based on the implementation of the asset/private key library separation framework. In addition, the framework can also optimize cross-Layer2 calls, including asset transfers between Layer1 and Layer2. 

Implementation of the asset/private key library separation framework  

Vitalik first stated a current situation. With the rise of smart contract wallets (such as multi-signature wallets), the private keys required to access certain accounts will change over time, and old private keys will no longer be valid. 

Based on this, if the user has an address on Layer2, including the Layer2 where the user is located, he does not know the address (because ETH uses the "counterfactual" EIP-1014 (CREATE2) protocol). In this case, only relying on the asset/private key library separation architecture can allow users to change their private keys:

 The user has a "private key library contract" (on Layer1 or a specific Layer2), which stores the verification private keys and change rules of all wallets.

 Layer1 and many wallets' "wallet contracts" can obtain verification private keys across chains.

IP-1014 (CREATE2) address algorithm

Layer2 is the best choice for storing private key libraries

V God explained that there are currently five main ways to solve the storage problem of private key libraries, which are:

 Merkle proof

 ZK-SNARK proof

 Special purpose proof (such as using KZG)

 Verkle proof

 No evidence required, relying on static identification

Considering the high network cost of Layer1, V God believes that the aggregation protocol is the best choice, because users can generate aggregate proofs to package user-submitted operations, thereby reducing costs.

Optimizing the delay of reading Layer1 status inside Layer2 to a minimum, and then using Layer2 to directly read Layer1 is an ideal solution to save proof space.

Although security is also an important assessment criterion, the security of storing private key libraries in Layer1 will be much higher than that in Layer2, but in the long run, such storage behavior is too costly and has the highest cost. Therefore, V God believes that storing private key libraries on Layer2 is an economical and secure approach.

Highlights

 To have a cross-chain social recovery wallet, the most realistic workflow is to maintain a wallet with a private key repository in one location, and one in multiple locations.

 A key element to make this possible is cross-chain proofs. We need to work on optimizing these proofs. ZK-SNARKs or custom KZG solutions awaiting Verkle proofs seem like the best options.

 In the long run, an aggregation protocol that generates aggregate proofs as part of creating a bundle of all User Operations submitted by a user will be necessary to minimize costs. This should probably be integrated into the ERC-4337 ecosystem, although changes to ERC-4337 may be required.

 L2s should be optimized to minimize latency in reading L1 state (or at least state roots) from within L2. It would be ideal for L2s to read L1 state directly, saving proof space.

 Wallets can not only be on L2, users can also put wallets on systems with a lower level of connection to Ethereum (L3, or even independent chains that only agree to include Ethereum state roots and reorganizations or hard forks in the event of an Ethereum reorganization or hard fork).

 However, the keystore should be on L1 or high-security ZK-rollup L2. Doing it on L1 saves a lot of complexity, but even that might be too expensive in the long run, so the keystore needs to be on L2.

 Preserving privacy will require additional work and make some choices more difficult. However, we should probably move to privacy-preserving solutions anyway, and at least make sure that anything we propose is forward-compatible with privacy-preserving.