Original Content:
As Ethereum’s L2 network competition heats up and the Bitcoin network ecosystem becomes increasingly rich, the Bitcoin L2 network has become the “next crypto highland.” As a newcomer to the Bitcoin L2 network with a dual-layer architecture and recently successful development of ZKP verification, Zulu Network is expected to be the first to connect the Bitcoin L1 network, Bitcoin L2 network, and L3 network.
Odaily Planet Daily recently conducted an in-depth interview with Zulu Network CTO Cyimon to shed light on the behind-the-scenes of the Bitcoin L2 network.
Q: Can you give a brief introduction of yourself, your past work experience, and the responsibilities you have taken on since joining Zulu Network?
Cyimon: I entered the blockchain industry in 2018, focusing mainly on the ZK field, with about six years of technical experience. I joined the Zulu team in October of last year. The reason for choosing the Bitcoin Layer 2 track was mainly due to the release of the BitVM whitepaper. Based on these theories, we can truly realize the vision of the Bitcoin Layer 2. After joining the Zulu team, I have been handling the overall technical direction and development-related work. We will provide a detailed introduction to this, including Zulu’s unique design and current technical progress. Overall, Zulu is a network that aims to bring more expansion features to Bitcoin.
It is worth mentioning that as the industry’s first Bitcoin L2 project to complete ZKP simulation using the Bitcoin Script language, Zulu has made significant contributions to the BitVM 2 official GitHub repository, earning high praise from BitVM inventor Robin Louis.
Q: What challenges does building an L2 on the Bitcoin network face? What kind of technical solutions do other Bitcoin L2 networks on the market use?
Cyimon: This question is crucial and directly reflects the core vision of Zulu’s establishment. As a Bitcoin L2 network, or even before the Bitcoin L2 network became popular, most people heard about the Ethereum L2 network. Whether it’s a Bitcoin L2 or an Ethereum L2, the main challenge they face is how to ensure that the L2 network inherits the security of the L1 network.
For Ethereum, this is a relatively simple task because it is already very mature, for example, it can verify ZKP and has a certain programmability. But when it comes to the Bitcoin network, it becomes a bit awkward because the limitations of ZKP programmability directly lead to the inability of the L2 network’s on-chain state to be directly verified on the Bitcoin network. Due to this limitation, many Bitcoin L2 networks on the market actually have no direct relationship between their on-chain state and the Bitcoin network itself, meaning their on-chain state may claim to be able to generate a ZK proof, but this proof was never validated on the Bitcoin network. So in a way, these Bitcoin L2 networks are more like sidechains, so I think a key challenge of building an L2 network based on the Bitcoin network is how to ensure that the L2 network enjoys the security of the Bitcoin network without forking the Bitcoin network.
The security here mainly involves two aspects: the first aspect is the economic security of the Bitcoin network, which can form a POS network through staking to maintain the validation of the off-chain state. If there are issues, the corresponding assets will be forfeited. The second aspect is the network security of the Bitcoin network itself, which is the POW network security. In this scenario, ZKP verification is not done through staking node networks but by putting it on the Bitcoin network. This is what we truly want to do and a key issue that a Bitcoin L2 network must solve, i.e., how to inherit the security performance of the Bitcoin network. So, in fact, the on-chain security of other Bitcoin L2 networks is not directly related to the Bitcoin network. The high difficulty problem here is how to complete ZKP verification on the Bitcoin network.
Zulu has been focusing on how to achieve programmability on the Bitcoin network and implement ZKP since the release of the BitVM whitepaper. After several months of effort, we finally announced a milestone achievement last week, which is the current ability to implement ZKP verification using Bitcoin Script (see Zulu open-sourced code for ZKP verification using Bitcoin Script, involving Groth 16/FFlonk mainstream algorithms). This is a significant technological breakthrough in the industry, as it means that once zk verify can be achieved through Bitcoin Script, it can implement a challenge mechanism similar to Arbitrum to penalize the malicious party. Therefore, this is a way to indirectly enjoy the security of the Bitcoin network. Compared to other Bitcoin L2 networks, this is a unique technological implementation by Zulu and a leading solution approach.
Q: In terms of design concepts and ideas, the official documentation mentions the dual-layer architecture multiple times. How should we understand this in terms of features, functions, competitive advantages, etc.?
Cyimon: We need to discuss this from the design concept behind Zulu to help those who are not very familiar with technology understand the dual-layer architecture clearly.
To discuss this, we need to first clarify why the crypto industry needs L2 networks or why Bitcoin needs L2 networks more. Just as the first question mentioned where the security assurance of the Bitcoin L2 network comes from. The reason Zulu adopts a dual-layer architecture is mostly for functional considerations. Take Ethereum as an example, because it is programmable, Ethereum L2 networks mainly help solve two problems for the L1 network: TPS and operating costs. But for the Bitcoin network, in addition to cost and TPS issues, we also want an L2 network that can provide support for expansion and implement functions that the existing Bitcoin network has not yet achieved. This is the reason for the design of the dual-layer architecture. Going back to Ethereum, in the early design stages, the Ethereum network was not a ZK-friendly native environment, and the emergence of L2 networks or the development route centered on Rollup provided an experimental field for more innovative designs. In other words, some innovative features or technologies can now be tried out on L2 networks on a small scale. If the technical superiority is confirmed and gains wider acceptance, it can then be fed back to the L1 network. This is also why Ethereum is gradually integrating Rollup and ZKEVM into the L1 network.
So returning to the Bitcoin network, in addition to helping the Bitcoin network expand TPS and reduce operating costs, expanding functions is also an important aspect.
This brings us to the other layer in our dual-layer architecture – the L3 network, which can be simply understood as the “function expansion layer.” It is based on the UTXO asset type of the Bitcoin network and adds programmability to increase its capabilities. This also lays the foundation for more developers to engage in research and development work in the future.
The current L2 network that has been launched primarily targets Bitcoin-specific DeFi, or what we commonly refer to in the industry as BitcoinFi. Since the Bitcoin network and Bitcoin itself are high-value assets, if we want to activate these assets, we generally prefer to use more mature DeFi frameworks. Zulu’s L3 is an extension platform based on UTXO programmability that often uses a new programming language and a new virtual machine. If we were to build a DeFi application right away, there might be security risks. So, before that, to enable existing Bitcoin assets to quickly access mature DeFi applications in the industry, a Bitcoin L2 compatible with EVM became the best solution. This allows the existing liquidity to be released through applications with higher security. The L3 network is to lay the groundwork for future development and innovation. This is a significant competitive advantage that Zulu currently has.
Most Bitcoin L2 networks that are currently EVM-compatible or only EVM-compatible allow users to move their Bitcoin assets to DeFi applications. However, for industry users and the Bitcoin network, there is relatively little innovation or incremental growth because the gameplay is not much different from Ethereum. Therefore, compared to other Bitcoin L2 networks, Zulu’s dual-layer architecture has more room for development.
Lastly, let me emphasize our security. As mentioned earlier, our security implementation mainly focuses on L3 networks being terminated in the L2 network, and the state of the L2 network is verified through ZKP to enjoy the network security of the Bitcoin network itself, which is our latest development achievement. From this perspective, Zulu is the only Bitcoin L2 network that can enjoy the security of the Bitcoin network.
Q: We have also heard about the development progress of Zulu bridge and Lwazi V4 technologies. Can you elaborate on this?
Cyimon: Lwazi V4 is the codename for the testnet version, and Zulu bridge is a unique bridging tool currently in development that allows for the verification of off-chain states through ZKP on the Bitcoin network, which is at the core of Zulu’s value proposition. When it comes to user participation, we will release a trust-minimized Bitcoin bridge in the future, where users can participate in experiencing the cross-chain asset bridging on the Bitcoin network. User participation will also help us conduct security and convenience testing for the Zulu bridge. Stay tuned for the release of the official documentation for more details.
Q: From an ultimate perspective, what applications do you think the Bitcoin network needs to support, what essential components should the ecosystem architecture have, and will the Bitcoin network produce multiple L2 networks like the Ethereum network?
Cyimon: The question of Bitcoin network application scenarios is worth addressing first. Currently, we can see that apart from Bitcoin, the Bitcoin network does not have any other assets, which is actually quite remarkable. Including previous projects like Inscription, and the recently popular Rune project, none of them have broken through the asset framework of Bitcoin. So, I believe that the Bitcoin network, Bitcoin itself carries huge potential energy. Specifically in terms of application scenarios, the first is similar to Babylon where existing assets are activated, releasing the liquidity power of these assets through staking or other actions. This is one aspect. After unlocking existing assets, can we then build on this to do something more?Enhancing cybersecurity is a highly anticipated application scenario, which is why some projects choose the path of asset pledging or re-pledging on the Bitcoin network. These trends stem from the massive funds available on the Bitcoin network, leading to the appreciation of Bitcoin network assets.
Given the current lack of high market value projects derived from the Bitcoin network, another important scenario is to support programmability based on Bitcoin asset types. This allows developers to diversify their application development based on UTXO asset types. For example, the previous Ordinals protocol had many index indexes running in a centralized manner, leading to differences in asset recognition due to varying platform standards. By developing programmability based on extended UTXO, indexes can be standardized industry-wide, similar to the concept of smart contracts.
The concurrent capabilities of extended UTXO (as each UTXO spend can be independent, unlike the account model that only allows one transaction at a time) can support many scenarios that require concurrent processing capabilities, thereby providing support for mass adoption in the industry.
Regarding the necessary components of the ecosystem architecture, bridging is considered a core component. This involves ensuring the secure transfer of assets between the Bitcoin network and L2 network while also ensuring that the L2 network enjoys the security protection of the Bitcoin network.
In terms of the number and development pattern of Bitcoin L2 networks, it is currently believed that the development of Bitcoin L2 networks has drawn inspiration from Ethereum. Therefore, there may not be as many L2 networks as seen in Ethereum. Bitcoin L2 networks may introduce chains with different virtual machines, such as projects building EVM-compatible networks on the Bitcoin network or Solana virtual machine compatible networks. Some may focus on creating networks compatible with the Move language. It is known that some are attempting to build SVM on Bitcoin, as Bitcoin L1 network lacks a virtual machine. Thus, Bitcoin L2 networks may exhibit greater diversity compared to Ethereum L2 networks.
Regarding Zulu’s development stages and upcoming milestones in the next three to six months, there are three main parts. Firstly, the most crucial Zulu bridge for the L2 network, secondly, the release of L3, and finally, the gradual open-sourcing of various mature technologies and features by the Zulu team to support more projects in adopting secure solutions.
From a technical perspective, in terms of developer, application, and partner selection, Zulu looks forward to collaborating with outstanding projects and teams to further develop the Bitcoin ecosystem. Zulu aims to serve as a true Bitcoin L2 network, helping to extend the functionality of the Bitcoin network while maintaining its security protection.
In conclusion, the ultimate vision of Zulu is to expand the functionality of the Bitcoin network comprehensively. The development milestones will focus on technical iterations and updates to bridge the gap between Bitcoin and other public blockchains.
Regarding Bitcoin Lightning payments and the Lightning Network, the current focus is on Bitcoin as a digital gold asset rather than as a peer-to-peer payment system, with the hope that developers will continue to expand the use of the Lightning Network.
In essence, Zulu aims to be a true extension layer for the Bitcoin network, offering a wide range of extensions including performance enhancement, cost reduction, and ecosystem expansion. The focus will be on continuous technical advancements to bridge the gap between Bitcoin and other public blockchains, with Zulu bridge, L3 network, and Bitcoin ecosystem expansion being the key targets for future breakthroughs.
