Dialogue Scroll Co-founder Haichen: The mainnet launch is a new beginning, with a greater focus on real-world applications in the ecosystem

Interview: Frank, PANews

Written by: zen, PANews

As an open-source Layer 2 solution led by Asian entrepreneurs, Scroll has been highly anticipated and followed by the community. After two years of intensive development and a year of testing, on October 10, 2023, the Scroll mainnet produced its genesis block at 2 PM. A week later, on October 17, Scroll officially announced the mainnet launch.

As of October 27, according to L2beat data, the total value locked (TVL) on the Scroll chain has exceeded 19.3 million USD; according to Blockscout data, the number of wallet addresses on the Scroll mainnet has surpassed 147,000, with a total of over 860,000 verified transactions. From October 20 to October 26, the average daily transaction volume was nearly 80,000, with the highest single-day transaction volume reaching 101,375 on October 22.

This week, Scroll co-hosted the ETH Hong Kong event with Web3 venture capital firm Newman Group at Cyberport in Hong Kong, marking the first major event organized by the Ethereum community in Hong Kong. During the conference, PANews conducted an exclusive interview with Scroll co-founder Haichen Shen. Below are the interview details.

PANews: Please briefly introduce yourself and Scroll.

Haichen: Hello everyone, I’m glad to be here today for an interview with PANews. I am Haichen, one of the three co-founders of Scroll, and I mainly oversee the engineering team within Scroll. To give you a brief background, I worked at Amazon Web Services (AWS) for a few years, primarily focusing on AI Compilers. Later, I met ZhangYe and Sandy during Ethereum community events and learned about zero-knowledge proofs, which piqued my interest. I believe this is a very promising field that can be used to create practical products and systems, ultimately scaling Ethereum to accommodate more transactions and reduce user fees.

PANews: Why did Scroll host the ETH Hong Kong conference?

Haichen: We realized that Hong Kong might be more business-oriented and lacks a strong Ethereum community. Hosting this event here allows many students in Hong Kong and builders from the Ethereum community in the Asia-Pacific region to participate, learn about the latest developments in Ethereum, and help expand the Ethereum community back into Hong Kong and the Asia-Pacific region. We believe this is significant for the developer ecosystem in Hong Kong and the Asia-Pacific region, which is why we decided to hold this event here.

PANews: What areas do the projects participating in this hackathon focus on, and what information are you expecting?

Haichen: Nearly 100 projects are participating in this hackathon, and we will select 16 of them for the final presentation competition. We will ultimately choose some winners and reward them. These projects mainly provide infrastructure services to Ethereum or Layer 2 for community developers, as well as projects aimed at enhancing user experience.

PANews: After a year of running the testnet, what does the official launch of the zkEVM mainnet mean?

Haichen: This is a very important milestone for us. We have spent about two and a half years completing the development of the entire infrastructure components, including the zkEVM circuits and the sequencer for generating blocks. After extensive testing on the testnet, we have ensured that everything is in place. In the last few months, we focused on optimizing various security aspects, bringing in independent external audits to ensure that all code has been audited by third-party organizations.

With the mainnet launch, users can now bridge assets from Ethereum to Scroll and use various applications on Scroll. This is a significant milestone, but also a new starting point. We will continue to roll out more features in the future to further enhance security, reduce actual user costs, and provide developers with more features to build better and more innovative applications.

PANews: After one week of launch, is the progress of Scroll's ecosystem development in line with expectations, and what points are worth noting?

Haichen: Overall, it is in line with our expectations. Since we announced the mainnet launch, over 15 million USD has entered our Scroll chain. We have already seen some DeFi applications generating transactions on Scroll, which is a satisfactory achievement. After about a week, we currently rank eighteenth in the overall Layer 2 TVL. We are also pleasantly surprised to see many contracts being deployed, with many developers starting to deploy more contracts. The growth in contract deployments is actually outpacing the TVL. We believe this is a very healthy sign, as more active developers will be building on it, and we are likely to see more innovative applications deployed on Scroll for users.

PANews: Why did Scroll choose the zkEVM-based zkRollup solution, and what is the significance of EVM equivalence?

Haichen: First, let me explain why we chose the zk route. We believe zk is a great solution for scaling Ethereum. zk provides users with more security, as zk Rollup actively submits proofs rather than passively waiting for challenges regarding errors, thus offering users faster and stronger security guarantees. All transactions generated on Layer 2 are proven correct by zk, providing a better user experience for both users and developers. The finality time for Layer 2 is shorter, typically within one to a few hours, allowing users to confidently use the validated state.

Secondly, we believe EVM equivalence is a very important metric, as it provides users and developers with a better experience. Developers do not need to install new plugins and can directly use the developer kits from Ethereum on Layer 2 without any modifications. In contrast, some other zkEVM solutions may require some changes. For example, zkSync requires the installation of certain plugins. This could introduce more bugs and lead to slight differences in underlying logic, resulting in unexpected reactions in corner cases, ultimately causing issues with transactions or applications. Therefore, we believe that EVM equivalence is crucial, and the entire EVM model has undergone extensive testing, proving to be a reliable execution model. We believe it also provides users and developers with more assurances, such as security guarantees.

PANews: From a technical principle perspective, what makes Scroll unique among various ZK-EVMs?

Haichen: As I mentioned earlier, our compatibility with Ethereum's EVM is very high. In terms of more detailed development, we write zero-knowledge proof circuits under conditions that closely resemble EVM, meaning that for each instruction in EVM, we have corresponding zk circuit components to prove that the instruction was executed correctly. Currently, while we do not fully support all precompiled contracts in the entire zk rollup, we support the most precompiled contracts, with about six currently supported.

We know that many zk developers want to deploy new zk applications, so we will support necessary operations on elliptic curves to provide users and developers with a more complete experience. For example, EC add (elliptic curve addition), EC MUL (elliptic curve multiplication), and EC Pairings (elliptic curve pairings). Additionally, in terms of the sequencer, our sequencer is based on Go-Ethereum (Geth), which is a popular implementation of Ethereum nodes. We have made some adjustments for the Scroll chain, while other parts follow the usage of the Go-Ethereum client, providing users and developers with stronger compatibility, as nearly all Ethereum native APIs can be fully replicated on Scroll.

PANews: Is there any information you can disclose about Scroll's token?

Haichen: Currently, there is no information that can be disclosed.

PANews: What are Scroll's next plans for ecosystem and developer incentives? Which projects will be prioritized?

Haichen: In the initial weeks, we will primarily focus on supporting basic infrastructure services, such as RPC, indexing, and various third-party cross-chain bridge ecosystem support, as well as oracles, which are necessary development environments and tools for developers. Once these are supported, we will see a wave of DeFi applications. We have already communicated with various DeFi projects, and they will begin deploying on Scroll within two to three weeks, at which point we will see more DeFi applications interacting.

Moving forward, we will build a more open and neutral platform for various developers to come and develop and deploy. We will not favor large or small projects but treat them equally, allowing them to enjoy the same support on Scroll. However, we may want to focus on projects with real-world applications, such as stablecoin payments or Account Abstraction wallet projects. We will likely concentrate more on these projects. We will also pay attention to supporting public goods, such as developer tools that benefit ecosystem development and provide support. I can hint that we will have some developer incentive activities in the future, possibly using NFTs to provide more incentives for developers to deploy contracts on Scroll.

PANews: Born in a bull market and growing in a bear market, has Scroll encountered difficulties and challenges during its entrepreneurial journey?

Haichen: We initially experienced a significant bull market, and our fundraising rounds went relatively smoothly. Overall, I think everything from development to now has been quite smooth. We raised some funding early on, which ensured that we could focus on development for a long time to come, working on the entire zkEVM and community ecosystem.

I believe the challenges mainly stem from technical aspects. While building the entire zkEVM, we encountered many challenges that we had not anticipated at the beginning. Subsequently, we discussed internally and collaborated with the open-source community (such as the Ethereum Foundation's Privacy and Scaling Explorations group) on how to solve the technical route of zkEVM and develop it together. Everyone reviews each other's code to check for bugs, which increases the overall reliability of our code. Of course, there were challenges, including discovering that the overall performance of the solution was not particularly good after completing the initial plan, leading us to undergo one or two rounds of code refactoring and optimization to finally reach the level we expected.

PANews: As a participant in the ZK-based L2 track, how does Scroll view the competition and development of zkEVM and the L2 track?

Haichen: Personally, I think the competition in the entire Layer 2 ecosystem is still in its early stages. There has been a significant shift this year; for the previous two years, the focus was more on Optimistic Rollup solutions, but this year, more zk Rollup solutions have emerged. However, zk Rollup still has some issues to address, including making the entire Layer 2 more trustless, so that it does not rely on a single project for technical support but allows more developers to participate. This will provide more security guarantees for Layer 2, enabling users to trust the security of zk Rollup and safely place their assets on Layer 2.

Additionally, I believe there is still much room for development in Layer 2, including the potential to develop new applications through zk Rollup that facilitate faster information exchange between Layer 1 and Layer 2. Moving forward, we need more developers to create interesting and innovative projects on zk Rollup. I believe the entire market is not a zero-sum game but rather one that can be expanded further.