Interview: Jack, BlockBeats, Vision, MetaStone

Organized by: Sharon, BlockBeats

Currently, blockchain is facing a triple dilemma: lack of scalability, security, and decentralization—lack of trustless cross-chain communication, lack of Rollup scalability when the number of transactions grows large enough, and inability to improve Maintaining high levels of security and decentralization while targeting throughput. This is a long-standing problem, and the essence of the problem is to find a way to store data securely in a smaller, lighter container without using a storage device that is too large or too expensive.

Most blockchains today are monolithic. The core functions of a blockchain, including execution and consensus, occur simultaneously and are executed by the same set of validators. Monolithic architectures are difficult to scale because every transaction must be initiated by a full node. Execution, leading to bottlenecks; while a modular blockchain is a blockchain that completely outsources at least one of the 4 components (consensus, data availability, execution, settlement) to an external chain.

Celestia is the first modular blockchain network and a cloud computing network for Web 3. It is a pluggable consensus and data availability layer that allows anyone to quickly deploy decentralized areas. blockchain without the overhead of bootstrapping a new consensus network. Some in the industry believe that Celestia is the most important underlying innovation in the blockchain industry since Ethereum. Both Ethereum and Celestia are building a secure base layer. This time, BlockBeats had an exclusive interview with Nick White, co-founder and COO of Celestia, at the TOKEN 2049 conference to explore the relationship between Celestia and Ethereum, as well as the story behind Celestia.

Without Celestia, Ethereum cannot scale Rollup

Among these three dilemmas, the lack of scalability has the greatest impact - only by enhancing the scalability of the blockchain can hundreds of millions of people also open the window to the chain. This is also the biggest dilemma faced by mainstream blockchains including Ethereum. Currently, Ethereum already has extension solutions such as Optimism, ZKsync and Starknet. However, these scaling solutions rely heavily on Ethereum itself for data availability. At the same time, Ethereum’s gas fees are still very expensive.

Previously, Vitalik, the founder of Ethereum, once described what he believed to be the ultimate form of the Ethereum blockchain, spending a lot of space describing a new Ethereum built by Rollup and DA. This undoubtedly points out the way for Ethereum to break through in the next ten years - modularization.

**BlockBeats: Can you tell us a little about you and your background? **

Nick: Of course. I'm Nick White. I am the Chief Operating Officer (COO) of Celestia Labs. We are building Celestia, the first modular blockchain network, which means that Celestia is a proponent of a new paradigm for building blockchains, where we no longer try to do it all in one protocol, but Separate the protocol into different layers, each focused on specific functionality, which can then be recombined to build blockchains and applications.

Therefore, Celestia focuses on the consensus and data availability layers of the stack without any execution. Execution is achieved through Rollup (one of the Layer2 solutions). People can deploy Rollup on top of Celestia, and Celestia provides a scalable decentralized block space for people to build on. So you can think of us as the first layer of a future designed specifically with Rollup in mind, to extend Rollup.

**BlockBeats: When did you first start hoping to adopt a modular blockchain? **

Nick: It all stems from two white papers that appeared in 2018 and 2019. The first white paper was co-authored by Celestia co-founder Mustafa Albasan and Vitalik, called "Data Availability Sampling and Fraud Proofs." In this paper, he shows that it is possible to build a blockchain that can expand the lock space with the number of nodes in the network, thus solving the scalability problem.

He then wrote another white paper called "Lazy Ledger" based on his previous work. "Lazy Man's Ledger" is a continuation and expansion of the concept of data availability expansion, in which he proposed a new idea - building a blockchain that is only responsible for data availability and does not perform any transactions. At the time, he called it a "client-side smart contract."

The client of the blockchain will execute transactions independently of the first layer, which is now Rollup. Rollup is actually the off-chain execution of smart contracts and applications. Therefore, "Lazy Man's Ledger" indeed introduces the concept of modular blockchain. Then, when Rollup came along, he further showed how the whole system works because Rollup can make the execution layer as scalable as data availability sampling.

**MetaStone: The launch of Ethereum’s project sharding will reduce the cost of Layer 2. Has it had an impact on Celestia? **

Nick: ETH sharding, which is Ethereum, is actually moving on the roadmap to mimic the way Celestia is building. Before that, they were building ETH 2.0, which is sharding technology, but in late 2020, they decided to pivot and follow the way Celestia was built. Over time, they gradually aligned their architecture more and more with Celestia's model. So, Danksharding is basically a different implementation of a similar idea to Celestia.

However, there are several differences, the first being time. Celestia is coming out in a few months and Danksharding is still in the design and research stages, it's hard to know when it will be out, I don't think they've even set a date yet, but they do have Proto-Danksharding, which is EIP-4844, But this will only result in a small, one-time increase in Ethereum’s block space.

Based on the demand we've seen deploying Layer 2, I don't think this is nearly enough to provide the required throughput. Therefore, Celestia will be launched at a time when people want to deploy Rollup in large quantities. I don't think Ethereum can scale Rollup without Celestia. And in the long term, when Danksharding launches, the problem is that it is similar to a data availability layer attached to a single first layer, which is the original Ethereum chain.

So, Ethereum has a lot of technical debt and baggage that needs to be developed on top of it, whereas Celestia has the opportunity to start from scratch so there isn't so much state bloat. We don't need execution, our network is very lightweight, simplified, and Ethereum doesn't have that luxury, they still have to carry the burden of Ethereum Layer 1, those are some of the differences I see.

DAS is more trustworthy than DAC

Allowing users to safely own data and the assets represented by the data will dispel ordinary users' concerns about asset security and help guide the next billion users into Web3. Therefore, an independent data availability layer will be an indispensable part of Web3. Data Availability DA (Data Availability) essentially means that light nodes do not need to store all data or maintain the status of the entire network in a timely manner without participating in consensus.

The currently existing DAS (Data Availability Sampling) and DAC (Data Availability Committee) are the two mainstream ways to verify data. The former verifies that a block has been published by downloading some randomly chosen blocks, the latter confirms that it has received the data by signing each update to the state with its quorum.

The industry generally believes that when an independent data availability layer is a public chain, it is better than an availability committee composed of a group of subjective people. Because if enough private keys of committee members are stolen to make off-chain data unavailable, the security of users' funds and data will be greatly threatened. Nick pointed out that what Celestia is currently doing is to make the data availability layer more decentralized - equivalent to providing an independent DA public chain with a series of verification nodes, block producers and consensus mechanisms to improve the security level.

**MetaStone: In the DA market, all DA layers mainly accept data from layer 2 and layer 3, but we know that most layer 3 cannot send their data to the DA layer due to data pledge, but Polygon A bridge will be used to receive this data. I'm wondering what your thoughts are on this and what method Celestia will use to receive data from layer 3? **

Nick: What it does is make sure that the bridge validates the availability of the data on Celestia. Therefore, a third party can publish their data to Celestia, but publish their status updates to another chain, such as Ethereum Layer1, Optimism, Polygon, etc. Aggregation contracts on those chains can verify the availability of data on Celestia through this bridge. So we're able to help expand that.

**MetaStone: In the current DA market, EigenLabs has also launched an EigenDA. At the same time, EigenLabs borrows from Ethereum’s original distributed nodes to secure other networks and reduce node operations. So, what do you think about this? **

Nick: Re-staking is an interesting idea that allows you to use existing funds, such as collateral, to stake a new protocol. But it doesn't inherently scale the blockchain, it's just a way for you to launch a new protocol without having to issue new tokens. Regarding EigenDA, the problem is that their design is not really about data availability. Data availability here refers to the kind of concept that comes to mind when you think of Ethereum, Danksharding, or Celestia. Because EigenDA is just a data availability committee, which is a multi-signature account, someone tells you that the data is available, but you can't verify it yourself. Therefore, EigenDA cannot really be compared to Celestia, they are not exactly the same product.

Another problem is that if they use re-staking ETH or any non-EigenDA token to secure EigenDA, there is no way to punish data retention attacks. A data retention attack is a non-attributable failure, meaning you cannot prove to a smart contract or any other entity on Ethereum Layer 1 that data was retained. So if someone actually did data retention, they wouldn't be able to penalize the re-staking of ETH. This way, you can actually attack EigenDA at zero cost. So, I think this is a deep problem in design. That's what I think of EigenDA.

**MetaStone: In the process of validating data, some off-chain data availability layers choose to use DAC to protect their data, while some other data layers choose to use DAS. What are your thoughts on DAC and DAS? **

Nick: Blockchains are actually verifiable computers. Therefore, you don't need to trust other people, such as a committee. Because the purpose of decentralization is to achieve by allowing end users to verify the chain. Therefore, the Data Availability Committee is not actually a blockchain because when using DAC, by definition you have to trust a committee. In contrast, data availability sampling is a method of directly verifying the chain by taking samples. Therefore, it is a true blockchain from a verifiability perspective. You don't need to trust Celestia's validators, you can validate yourself. Even if they try to deceive you or collude, they can't fool you. This is a fundamental difference, very important, and people should be aware of it. This is also what I said before, EigenDA is not the same thing as Celestia because it is a DAC, you can't really compare.

**BlockBeats: Does DAS also have more benefits for adding or removing nodes to the network? **

Nick: Of course. One of the superpowers of a network like Celestia is that due to data availability sampling, this means you can increase the block size as you add more nodes in the network, which is very powerful. Because in a monolithic chain, you can only use the same block size no matter how many people run nodes. In Celestia, you can actually increase the block size as more nodes are added and sampling begins.

We want to create a culture where users run nodes on their wallet or browser. This means that as more users join the network, the number of nodes increases, so blocks can become larger, providing more block space for new users and new applications. So there's a positive feedback loop here where users actually provide scale for their applications.

KZG commitment may be used in the future

Quantum Gravity Bridge (hereinafter referred to as QGB) is a data availability bridge between Celestia and Ethereum. It is deployed on Ethereum by Celestia, and then Ethereum Layer 2 operators can publish their transmission data. to the Celestia network, where it is put into a block by Celestia's Proof-of-Stake (PoS) validators. This data is then forwarded from Celestia to Ethereum in the form of a proof of data availability. The proof is the Merkle root of the L2 data signed by a Celestia validator, proving that the data is available on Celestia.

The QGB contract verifies the signature on the DA certificate from Celestia. Therefore, when the Layer2 contract on Ethereum updates its state, it does not rely on the transfer data published to Ethereum, but checks whether the correct data is provided on Celestia by querying the DA bridge contract. The contract will respond positively to any valid proof feedback previously forwarded to it, otherwise it will respond negatively. Nick pointed out that Celestia will provide high-throughput data availability for Ethereum Layer 2, which is more secure and cheaper than other off-chain data availability solutions.

**BlockBeats: Do you think a quantum gravity bridge would be more expensive or cheaper relative to the cost of EigenDA? **

Nick: One of the problems with EigenDA is that they haven’t released any information about how they actually built it. So, it's hard to know what it would look like without the code. I think for EigenDA, depending on how they are built, it could be expensive to prove, because you have to generate KZG commitments (Kate-Zaverucha-Goldberg, polynomial commitment scheme) and verify the signature on Ethereum, like every For each batch you have to verify a bunch of signatures. So this may actually consume a lot of Gas. The nice thing about QGB is that we designed it in a way specifically to minimize gas costs.

First, we have batch processing. It's like there are multiple Celestia blocks, they are all batched into one block, and then a commitment is generated, signed, and then published to Ethereum. So, instead of delivering and validating every block, you only do it once in a batch, which significantly reduces the gas cost of validating commitments.

Secondly, we are also building a zero-knowledge QGB, which will verify all these signatures through zero-knowledge proofs, further reducing the Gas cost of verifying commitments on Ethereum Layer1. Because the gas cost of verifying the commitment on Ethereum Layer1 is a large overhead for any off-chain DA. And then there's the actual DA cost of paying for data like on Celestia and EigenDA, it's hard to know right now what that's going to cost. I think the cost is going to be very, very low, in either case, so low that I doubt it's going to be a different factor unless there's sudden congestion in Celestia or something else that makes the cost very high.

**BlockBeats: You just mentioned KZG, but why hasn’t Celestia used KZG yet? What’s the thinking behind it? **

Nick: Yeah, the problem with the KZG promises is that they're still fairly new and computationally very slow. Therefore, creating blocks will be more expensive if KZG commitments are used. Also, as the block size grows, you have to calculate more and more open values, which causes slowdowns. Therefore, Celestia made the very practical decision to use ordinary Merkle trees (hash trees) with fraud proofs.

But the thing is, if it becomes practical, we can easily replace it with a KZG commitment. Excitingly, a few weeks ago at the SBC (Science Blockchain Conference), Ethereum Foundation researcher Dankrad Feist shared some promising research on KZG hardware acceleration, and we are paying attention to this area if there is any Any changes and improvements will be fully considered for replacement. But KZG adds a lot of complexity, so it's a challenge.

**BlockBeats: I want to ask some questions about Rollkit (a modular rollup framework). What role do you think Rollkit will play in the future? **

Nick: The first thing people should know is that Celestia is completely neutral. In fact, we are currently working with almost every rollup SDK to integrate Celestia as a DA option. We started Rollkit when there was no open source rollup framework, because there was Layer2 at the time, but they were all trying to build their own single thing, rather than trying to build a software SDK for anyone to be able to build their own rollup, and that's what we incubated Rollkit reasons.

I think one of the unique things about Rollkit is that it is the first to be designed with a concept that is not tied to Ethereum and does not involve settlement with smart contracts. Therefore, it is more suitable for running Sovereign rollup. Another important aspect is that Sovereign Rollkit is compatible with ABCI (Application BlockChain Interface, blockchain application interface), so any Cosmos SDK application or execution environment that is compatible with ABCI can be compatible with it. People have taken many different virtual machines and made them ABCI-compatible and then been able to start them on Rollkit. This is very important because it opens up another ecosystem of projects for building rollups. Another cool thing is that the Rollkit team built a fraud proof system for Cosmos SDK applications. So it's actually possible to build an optimistic rollup on Rollkit, which is very exciting.

**BlockBeats: Is there anything you want to say to Chinese developers or practitioners? **

Nick: We're very excited to have a greater presence in China, and we know that China played such an important role in the origins of blockchain and cryptocurrency from the very early days. There are so many talented engineers and users in China, and the Chinese community is full of enthusiasm. So, we are very much looking forward to being able to engage and participate with them. I have lived in Hong Kong for a year and a half and have traveled around China a lot. I love Chinese culture and I really appreciate the Chinese mentality. They are full of desire. , has a builder’s mentality and a striver’s mentality, which I like very much.