Interview: Jack, BlockBeats
Translation: DaiTJ, Jaleel, BlockBeats
Editor: Jack, BlockBeats
After nearly five years of research and development, the Linea team announced the launch of the mainnet Alpha during the Paris ETHCC conference in July, which attracted widespread attention from the community. As of August 4, according to Dune data, its mainnet had attracted more than 100 ecological projects within a week, with more than 20,000 ETH, more than 170,000 transactions, and more than 127,000 interactive addresses, making Linea one of the projects with the largest transaction volume and the fastest growth rate on Goerli.
Since the beginning of this year, the ZK track has entered the stage of an arms race, and this competition has entered a white-hot state in recent months. zkSync and Starknet followed the OP camp and competed to release their own L3 plans. Also at the beginning of the year, Linea squeezed into the already crowded ZK track with a sudden appearance, and gradually attracted more and more users and attention as a dark horse.
In March this year, "Web3 giant" ConsenSys launched a public testnet and renamed it Linea. This test network, which was launched in the fourth quarter of 2022, has processed more than 350,000 on-chain transactions in 3 months. In an official blog post, the team wrote: "Linea represents the next stage of evolution of ConsenSys zkEVM, which is to power the next generation of dApps on Ethereum."
This blockchain expansion solution built by the owner of MetaMask hopes to combine powerful zero-knowledge proofs with the ecologically active EVM to help developers build or migrate existing dApps in the simplest way. As an EVM-equivalent Type 2 zkEVM, Linea provides new possibilities for solving the compatibility problem between ZK Rollup and EVM. In addition, ConsenSys also hopes to make full use of its ecological advantages to allow Linea to natively integrate the company's MetaMask wallet and developer toolkit Truffle.
Declan joined the ConsenSys team as Linea product lead in 2021. His core responsibility is to think about the features that the Linea core development team should drive, and to gain insight into the importance of these features and the challenges that customers and partners may encounter when using our network. However, Declan said in the interview that from a broader perspective, his long-term goal is to gradually make his role "redundant."
“It may sound arrogant, but I think the real success for Linea is that people pay more attention to our Web3 infrastructure and team. When people focus on the application itself rather than the infrastructure behind it, we know we are on the right track. This mindset is not unfamiliar in the Web2 world. For example, people usually don’t care which cloud server Facebook runs on, they really care about the Facebook application itself. So this is what we are going to do in terms of infrastructure.”
Recently, BlockBeats interviewed Declan Fox and discussed in depth Linea mainnet Alpha, ConsenSys ecological landscape, the current status and future of the zkEVM track, as well as account abstraction, multi-prover and other topics.
About Mainnet Alpha
At the ETHCC conference in July, Linea released its mainnet Alpha. Driven by the airdrop expectations and a series of mission activities, in less than a month, the TVL on the Linea network has exceeded 30 million US dollars, and more than 100 application projects mainly based on DeFi have quickly emerged in the ecosystem. However, during the interaction process, there are many feedbacks about "difficult cross-chain" and "slow interaction". What explanation will the Linea team give for this?
According to L2 BEATS data, Linea mainnet TVL grew to over $30 million in about two weeks and is currently stabilizing at around $28 million.
BlockBeats: First of all, congratulations to you. The TVL of Linea mainnet has exceeded 30 million USD in such a short time. In your opinion, what is the main reason?
Declan Fox: I think there are two main reasons for our success. First, as you said, we have accumulated a lot of momentum from the testnet. The Linea testnet launched a 9-week "Linea Journey", where users can experience different themed dApps every week, such as DeFi Week, NFT Week, Cross-chain Week, etc. This event was very successful, we saw about 50 million transactions, and attracted many new and interesting protocols to join, such as the Account Abstraction Protocol, which attracted more than 1 million user operations on the testnet.
We launched the mainnet very quickly after the testnet event, bringing this momentum forward. Secondly, at the launch of the mainnet, we also conducted an NFT airdrop, which was one of the largest on-chain NFT airdrops, airdropping 352,000 NFTs to participants in the testnet event to reward them for helping test the network and promote the mainnet launch. We also opened up the public free minting of NFTs to more people.
I think the second reason is that people see the prospects of Linea and are full of expectations for the future of Linea. As a zkEVM public chain, Linea can seamlessly migrate existing dApps or develop new dApps for developers. At the same time, Linea is also integrated with other ConsenSys products, and it is integrated into MetaMask by default when the mainnet is launched.
Not only does this make it easier to onboard users, but for developers it also means their users can easily access dApps on the Linea mainnet. I think people see the value in this integration and are joining the Linea ecosystem even though it’s still in its infancy. We also intentionally marked this as an Alpha release to make it clear that this is a major milestone. There are now over 30 million TBR on Linea, not including our upcoming Token Bridge, which will enable cross-chain stablecoins and other ERC 20 tokens.
Linea has many exciting features coming soon, and many dApps are waiting for these features to go live. In short, Linea has made a good start so far.
BlockBeats: You just mentioned many DeFi and NFT applications based on Linea. With the launch of the mainnet Alpha, what kind of applications do you most want to see appear on Linea?
Declan Fox: DeFi is definitely a focus area for Linea. DeFi already occupies an important position in cryptocurrency and Web3, and Linea brings more possibilities to DeFi.
First of all, Linea is not only a general smart contract platform that supports the combination of different DeFi protocols, but also provides lower gas fees and higher throughput, which is not available on Ethereum. This brings a better user experience for DeFi users.
At the same time, as a ZK rollup, Linea inherits the security of Ethereum and does not need to make dangerous trade-offs like sidechains. As a ZK rollup, Linea can complete the finality of L2 transactions in minutes, which is critical for DeFi, and can provide finality guarantees for high-value transactions in minutes, instead of weeks as in the past.
In addition, considering the cross-chain bridge with other systems such as Ethereum, Linea's fast finality can also greatly improve the efficiency of cross-chain fund use. This is similar to a country that has abolished capital controls and can attract external funds more flexibly.
In summary, as a zkEVM rollup, Linea brings unique advantages to DeFi, ensuring security while providing an efficient and low-cost user experience. This will be the key to the flourishing of DeFi on Linea.
Blockbeats: Next, I would like to ask about the delayed withdrawal time. Previously, Linea announced that for security reasons, it would artificially set a withdrawal delay of at least 8 hours. Can you explain the reasoning behind this move?
Declan Fox: The 8-hour withdrawal delay can be seen as a temporary safety measure or "training wheels". As I said, the Linea mainnet is still in the Alpha stage. We have just deployed the system and need to ensure that users' assets are protected while the system is still in its early stages.
The purpose of setting an 8-hour withdrawal delay is to allow enough time to suspend operations or intervene if there are any problems with the rollup or we need to investigate to protect user assets. We mentioned in the risk disclosure document that a security committee can be activated to take action and intervene if necessary. We don't want to do this, but it is a safety measure.
The withdrawal delay is currently 8 hours, and we will gradually remove this limit as we learn more about the system and the mainnet is running longer and everything is working. I believe zkSync still has a withdrawal delay of 21 hours, or even longer. But all of these systems have "training wheels" at the beginning, and I believe that these limitations will continue to decrease over time.
BlockBeats: However, when interacting with the Linea network, we do hear complaints about network latency. What is the reason for this?
Declan Fox: There are two types of delays. The finality on Layer 2 is softer, while Layer 1 is the finality of transactions confirmed by Ethereum itself. Currently, the delay on Layer 1 is mainly caused by the 8-hour withdrawal delay we set, but this will gradually decrease over time.
Currently Linea itself has a delayed block time of 12 seconds and a quota of 30 million gas. In the coming months, we will gradually reduce the block time. Reduce latency. Technically there is no bottleneck, we just want to roll out the system in stages. The next stage will reduce the block time by about 60%, bringing it to a block time of 4 seconds and a quota of 15 million gas, and then further reduce the block time and increase the quota.
It is not easy to reduce latency and increase throughput, but we are in a good position because we have the technical support of the Basu team. The Basu team is currently executing blocks on Ethereum Layer 1 and will become a sorting node for Linea in the future.
This is an experienced team that has developed battle-tested client software that can be seamlessly applied on Linea. This will be a key differentiator in ensuring that we can achieve both fast block times and large transaction volumes. In short, this is not a technical bottleneck, but the result of a phased and gradual rollout of the system.
About Linea and ConsenSys
It has to be admitted that many people pay attention to Linea because of the powerful backer behind it - "Web3 giant" ConsenSys. This OG crypto company founded in 2014 now has business throughout the entire crypto industry. As one of the largest and most basic entities in the field of blockchain technology, ConsenSys has top computer scientists, protocol engineers, software developers, and enterprise delivery experts. In 2018, ConsenSys was called "the most famous and most common decentralized application developer and promoter in the Ethereum community" by The New Yorker.
Among the many products it has created, MetaMask is undoubtedly the most influential. Now, this Web3 wallet with a large user base will bring Linea a natural advantage in the number of users. So far, Linea has raised $726 million in multiple rounds of financing, with a valuation of approximately $7 billion. As a strong hitter of ConsenSys, Linea will undoubtedly carve out a niche for ConsenSys in the expansion track with the largest market space. Of course, this also leads to concerns and thoughts about the decentralized spirit of Web3 and the centralized development of large teams.
ConsenSys founder and CEO Joe Lubin speaks at the 2019 Ethereum New York Conference, with the background title "The Age of Collective Capitalism"
BlockBeats: In your opinion, what role does Linea play in the ConsenSys ecosystem?
Declan Fox: ConsenSys has a whole suite of products. ConsenSys has been around since the beginning of Ethereum, and its founder, Joseph Lubin, is also a co-founder of Ethereum. You could say Ethereum is in the blood of ConsenSys. ConsenSys has been supporting Ethereum throughout its development, launching Infura, which manages more than half of Web3 traffic, and also incubating MetaMask, a leading Web3 wallet.
ConsenSys has also incubated many public products, such as Baesu (one of Ethereum's leading execution clients), Teku (one of ConsenSys's important execution clients for Ethereum 2.0), Web3 Signer (a tool for securely signing private keys or transactions), etc. Linea is a key infrastructure to expand Ethereum's transaction capabilities. We realized this need a few years ago, and we also needed to maintain the network effect of EVM during the expansion process.
Therefore, Linea can be said to complete the ConsenSys technology stack to influence and support the entire process from the user initiating a transaction through MetaMask to the RPC layer and actually executing the transaction on a scalable universal platform, which is EVM-compatible Linea. It can be said that Linea perfectly integrates into the solution portfolio provided by ConsenSys to help promote the development of the entire ecosystem.
BlockBeats: But this has also caused some people to worry that ConsenSys is becoming a centralized force in Web3 and the crypto world. Most people use MetaMask as their wallet, and ConsenSys provides them with RPC, and soon more people will use the Linea network. I wonder what the Linea team thinks of this view?
Declan Fox: I think we should see that all of these products have plans to move towards decentralization and permission-free innovation.
Looking at them one by one, first of all, Linea has released a decentralization and trust minimization roadmap when the mainnet was launched, clarifying that Linea's operations and governance will be gradually decentralized and reduce dependence on ConsenSys. MetaMask users can also choose different RPC nodes and use non-Linea networks. The team is developing MetaMask Snaps, which allows any developer to extend MetaMask without permission.
Linea also supports the use of any wallet. It can be seen that ConsenSys has promoted the development of the entire Web3 ecosystem by providing these key infrastructure products. However, the core concept of these products still adheres to the principles of decentralization and user freedom of choice. Users can choose to exit at any time according to their needs.
BlockBeats: Let's talk about account abstraction on Linea. As an L2 network that natively integrates MetaMask, can Linea better assist MetaMask in achieving innovation in account abstraction?
Declan Fox: Yes, our philosophy is permissionless innovation. So even for Linea today, there are other wallets that support Linea. Likewise, MetaMask will continue to support all other networks except Linea. We are working hard to find ways to improve the user experience together, but there is a delicate balance between maintaining permissionless innovation while creating an environment that can solve user problems and move the space forward.
It is not realistic to implement account abstraction at the protocol layer in the short term. Although it is on Ethereum's roadmap, we will not see the implementation of EIP-4337 tomorrow. We have currently implemented EIP-4337 and smart contract accounts at the application level, but it is still very costly and more suitable for application on Layer 2. Linea, as a Layer 2 zkEVM public chain, is fully compatible with the Ethereum mainnet.
Therefore, various standards promoted by the Ethereum community, such as 4337, can be easily implemented on Linea. This allows us to leverage the rapidly growing community of account abstraction and support this feature from day one of the Linea ecosystem. In addition, we will also seek to support new endpoints to simplify management and protect the RPC layer and serialization layer from denial of service attacks. These all come from the greater Ethereum community consensus. Since Linea is a fully compatible zkEVM, we are fortunate to be able to easily join and continue the network effect of Ethereum.
About zkEVM and RaaS
When talking about Linea, the topic of zkEVM cannot be avoided. As the "most competitive" track in the crypto industry, the zkEVM field brings together the most capable and intelligent developers in the industry. In addition to different types of technical implementations of ZK L2, "RaaS" has also recently become the "hardest hit area" for this group of geniuses. After the OP camp launched OP Stack and Orbit, zkSync and Starknet followed suit and released ZK Stack and Appchain. As one of the powerful representatives of zkEVM, will Linea have the same action in this field?
The Rollup SDK Landscape by Kayla Phillips, Partner at Truffle Ventures
BlockBeats: Next I want to talk about the general topic of zkEVM. Why did Linea choose to make Type 2 zkEVM? What is the biggest advantage of Linea compared to Polygon zkEVM and Scroll?
Declan Fox: Our decision to build a Type 2 zkEVM dates back 4 years ago, in January 2019. At the time, our R&D team, Consensus RD (which also helped implement the merge and engine APIs), was working on scaling solutions. In 2019, a lot of discussion was focused on optimistic rollups, and zero-knowledge technology was still in its infancy, and EVM was not easy to simulate directly as a circuit.
So many people are unwilling to go the route of zero-knowledge proofs, and instead build their own zkEVMs, which have their own programming languages, and EVM has the largest ecosystem of developers, tools, and dApps in Web3. Considering the huge EVM ecosystem, we don’t want to start from scratch, but to maintain the network effect of EVM. So at the time, we believed that zero-knowledge proofs were the best expansion solution for the future, and we should also maintain the network effect of EVM. So we set out to achieve this goal, and after 4 years, we finally made a zkEVM that is both high-performance and compatible with EVM.
Being Type 2 means that we are largely comparable to EVM, we use the same Solidity compiler as Ethereum, and the RPC interface is also compatible with Ethereum JSON-RPC. This is very developer-friendly, they don’t need to learn new languages or new tools, and existing dApps can also be seamlessly connected. This is also good for decentralization, users can choose to exit at any time, and there is no risk of vendor lock-in. We follow Ethereum’s standards and are consistent with any project that implements EVM, which is also good for decentralization.
There are other projects that are building similar Type 2 zkEVM. I think the difference between Linea and other projects lies in two main aspects: one is technical implementation, and the other is ecological integration.
On the technical side, we can bring higher performance. Specifically, the speed and verification cost of the Prover in zero-knowledge proof are critical to user experience and transaction fees. We started building our own Prover in January 2019, and after 4 years and a lot of R&D resources, it can be said to be the best in the industry. We directly arithmetize EVM operations instead of adding intermediate translation steps. This allows us to make optimization adjustments at a lower level, which other systems cannot do.
In terms of ecological integration, Linea has been deeply integrated with other products under ConsenSys. For example, the native integration with MetaMask is just the beginning, but it has demonstrated the possibility of providing a complete user experience from wallet to RPC to execution. In addition, Infura provides infrastructure support to improve the stability and security of Linea. Finally, the Basu team provides us with execution clients and sorting nodes. This collaboration can create a more comprehensive and coherent user experience, which is difficult to match on other platforms.
BlockBeats: In addition to different types of ZK Rollups, another popular concept recently is "RaaS" (Rollup as a Service). As a strong competitor in the zkEVM field, does Linea have any plans in this direction?
Declan Fox: This is an interesting topic indeed. In general we are talking about the proliferation of Appchains or chains for specific use cases, which is not a new concept. I think with the advent of rollups, it is now much easier and more meaningful to spin up a new chain than the monolithic Appchains of the past.
The reason why someone wants to do this is sometimes because they need a more flexible execution environment, or they may want to have their own isolated block space and fully control the throughput and needs of their application. I think it is unlikely that there will be only one shared execution environment to handle all transactions in the future. This is similar to the development of computing, which initially ran multiple applications on a single server, and then later had a trend of one application per server.
Of course, there is still value in shared execution environments, and we can continue to push forward with their development to see what use cases can be built. Shared execution environments enable synchronous composability, which is difficult to replicate in a fragmented multi-chain world. Linea has committed to open source code, so the Linea technology stack can be instantiated. If the trend of fragmentation continues to intensify and there is more demand for different instantiations of the Linea virtual machine, then extremely fast proof generation will be critical in order to verify the state with other chains and ensure a smooth user experience.
Linea happens to have a very fast Prover, so if this trend continues, Linea's technology stack and virtual machine will be very attractive to teams looking to build their own execution environment and eventually roll up to the Ethereum mainnet. Many teams are aware of this in preliminary discussions, but we haven't received any official news yet.
About Multi Prover and the future
In the Linea team, there is another focus, that is, Multi Prover. What does this concept refer to? What can multi-prover bring to zkEVM and the encryption industry? Why does the team think it is so important?
BlockBeats: Linea has been promoting the concept of "multi-prover". What are the team's current thoughts on this proof generation model?
Declan Fox：Yes, this is what we mentioned in the decentralization and trust minimization roadmap released when the mainnet Alpha was launched. The basic idea is that Layer 2 transactions or batches of transactions can be proved by multiple zero-knowledge proofs at the same time. As long as the majority of them are verified on Layer 1, security can be guaranteed. This is more reliable than a rollup with only a single prover and there is no single point of failure risk. As Ethereum continues to develop, the specification needs to be re-audited and updated, and the multi-prover model can help get rid of various limitations.
As a zkEVM that closely replicates the EVM spec, Linea is in an excellent position to unlock the multi-prover model. I think once this is achieved, it will attract new risk-averse enterprises, liquidity, and users to Layer 2. Because it gives them better assurance that even if a prover is vulnerable, the system will remain secure. This is similar to having multiple execution clients on Ethereum mainnet to provide diversity. We hope to replicate the same level of security on Layer 2.
BlockBeats: Does the team currently have a mature design plan?
Declan Fox: The specific design of multiple provers is still an open topic, and we don’t want to converge on a fixed solution too early. But basically, there will be three different implementations of zkEVM generating proofs for a batch of transactions at the same time. As long as a quorum is reached on the Layer 1 verification contract, such as two out of three implementations are valid, then security can be guaranteed even if one implementation has problems.
Multiple provers also allow us to innovate more in Prover because there are fallback guarantees. In short, multiple provers bring a lot of interesting possibilities, which is also a long-term goal in our roadmap. We will remain open to the specific technical solutions and not fix them too early. Our goal is to achieve security diversity similar to the Ethereum mainnet in Layer 2. Multiple provers not only improve stability, but also give us more room for innovation in proof generation, which is very exciting. It will still take time to achieve multiple provers, but it is definitely our long-term goal and vision.
BlockBeats: Is there any discussion within the team about what interesting things can be done with the multi-prover model?
Declan Fox: From a user's perspective, the multi-prover model is roughly the same as it is today. But it gives developers and users greater confidence in the maturity of the system because of the increased diversity and resilience to errors. This is similar to how Ethereum mainnet has a variety of execution clients and consensus clients. If one of the clients fails, Ethereum can still be secure as long as the overall diversity is achieved. We are applying these design principles of Ethereum to Linea and Layer 2.
BlockBeats: Overall, what do you think is the most important thing for the team to do next?
Declan Fox: What we are most concerned about is the growth of user adoption, and we plan to start from several aspects.
First, continue to reduce transaction costs. Linea's fees are already much lower than Ethereum, but there is still room for further reduction in the short term. We can do this by aggregating proofs, where we use zero-knowledge proofs or validity proofs to complete second-layer transactions on Ethereum. In fact, we can aggregate many proofs together and recursively prove them in order to spread the fixed proof verification cost over a larger set of transactions, reducing gas fees.
Data compression can also help reduce the cost of calling data from Linea to Ethereum. We also hope to apply EIP-4844, which will also reduce the cost of publishing call data to Ethereum. This Ethereum protocol change will be applied later this year, and we will pass on the cost savings to users at that time.
The second is to improve the entry experience for new users. Simplify the process of wallet opening and initial use of DApps through account abstraction and other means to attract a new wave of users to join. We have implemented the application of EIP-4337 for account abstraction on Linea. On the Linea mainnet, we are also exploring the possibility of opening a wallet without entering a password with partners such as Pimnico.
We will also strengthen security. We will encourage ecosystem partners and security-focused protocols to provide insights and information about malicious smart contracts to users, helping users avoid being scammed in a non-permissioned manner. There are currently many frauds on various chains, which is not conducive to large-scale user adoption. We will strive to improve security in a decentralized manner while maintaining openness.
