Inventory of DA solutions

In the previous article about data availability, "Web3 Popular Science | Why is data availability so important to Layer2? (Part 1)", we introduced that the data availability (DA) problem faced by L2 is mainly the trade-off between security and cost. Under the trade-off, on-chain and off-chain DA solutions are also produced. The following will introduce these two different solutions in detail.

On-chain solution: Proto-Danksharding

The on-chain solution means that L2 still uses Ethereum as the DA layer and relies on Ethereum to reduce data availability costs.

Proto-Danksharding (also known as EIP-4844) is Ethereum’s solution to reduce the cost of data availability. It introduces a new transaction format — Blob. The transaction data uploaded by L2 will be stored non-permanently in the Blob format on the Ethereum consensus layer, bringing cheaper data availability to L2.

This means that Ethereum will serve as a real-time bulletin board in the future. The data on the board will be deleted after a period of time, and L2 must find a way to store backups of all data on its own.

Proto-Danksharding is expected to go live in Ethereum's Cancun upgrade at the end of this year.

Off-chain solutions

In layman's terms, off-chain solutions are to stop using Ethereum as a DA layer and instead look for a more economical way to obtain data availability. Based on the differences in decentralization and security, off-chain solutions can be divided into four types: Validium, Data Availability Committee (DAC), Volition, and general DA solutions.

  • Validity

In the expansion plan initially explored by Ethereum, the one that uses validity proof and publishes data on the chain is called ZK Rollup, and the one that also uses validity proof but publishes data off-chain is called Validium; the one that uses fraud proof and publishes data on the chain is called OP Rollup, and the one that also uses fraud proof but publishes data off-chain is Plasma.

The Plasma expansion solution has now been abandoned by Ethereum. After Ethereum announced the expansion route centered on Rollup, Validium has gradually fallen into disfavor. However, because the transaction data released by Validium to the off-chain is managed by a centralized operator, Validium is now specifically referred to as a highly centralized DA solution.

In this model, although the privacy of the transaction parties is greatly protected and the DA cost is reduced to a minimum, the risk is also the highest. If the off-chain operator fails or acts maliciously, the user's funds will not be recovered.

  • Data Availability Committee (DAC)

In order to reduce the risk of single point failure caused by a single operator, Validium is currently mostly used in conjunction with the Data Availability Committee (DAC). DAC is similar to a consortium chain, consisting of multiple authoritative or trusted node members, which will save copies of transaction data and make the data public when the operator fails or acts maliciously, making it easier for users to withdraw funds.

The operating cost of DAC is also relatively low, but from a security perspective, a small DAC (8-10 people) is still prone to private key theft or collective malicious behavior, and on-chain funds can also be frozen or stolen.

  • Volition

Volition is a hybrid model that allows users to choose whether the data of a single transaction is published on-chain or off-chain. For example, in a DEX that chooses this model, users can control multiple accounts and transfer assets to off-chain data accounts for frequent and cheap transactions when they need to trade, and then transfer assets back to the on-chain data account after the transaction is completed.

Therefore, compared with pure Validium, Volition can inherit part of the security of Ethereum.

  • Universal DA Solution

The DA off-chain solutions discussed above are all in the context of Ethereum, but there is also a general DA solution that can not only provide data availability for Ethereum's L2, but also serve more chains and projects. For example, EigenDA, Celestia, Avail, etc. will be introduced in detail in the next section.

Although the technical implementations of general DA solutions vary, the overall idea is to enhance the security of data availability in order to achieve public chain-level security. Therefore, they have their own verification nodes, block producers, and consensus mechanisms, but without smart contracts.

DA layer project introduction

Under the concept of modular blockchain, Ethereum occupies almost 90% of the consensus layer and settlement layer. After fierce competition, the execution layer has initially formed a "four-legged tripod" pattern (i.e. Optimism, Arbitrum, Starknet, zkSnyc). Only the data availability (DA) layer is still in its infancy. The following author will introduce several popular DA layer projects for readers' reference.

StrongEx

StarkEx is a framework developed by the StarkWare team that provides expansion solutions for specific applications. Because it also provides data availability solutions for applications, it is also classified as a DA layer project. StarkEx has three data availability modes: on-chain, Validium, and Volition. Different from the pure Validium introduced above, the Validium solution provided by StarkEx integrates DAC to improve security.

Projects currently using StarkEx to provide data availability include dYdX v3, Immutable, Sorare, DeversiFi, etc.

zkPorter

zkPorter is an off-chain DA solution proposed by zkSync's R&D team Matter Labs in April 2021. zkPorter is an independent chain dedicated to L2 publishing transaction data. The chain maintains security through the PoS consensus mechanism. zkSync token holders can stake tokens to become zkPorter guardians to verify and sign blocks. This is one of the reasons why the community believes that zkSync will issue coins and airdrops, because zkPorter's consensus mechanism involves governance tokens.

In addition, in Matter Labs' vision, accounts on zkPorter can interact seamlessly with accounts or contracts on ZK Rollup (zkSync Era). From the user's perspective, perhaps the only obvious difference is that the fees of zkPorter accounts will be many times cheaper.

ZK Rollup and zkPorter have strong interoperability

However, it is worth noting that although zkPorter was proposed a few years ago, there is still no movement, and Matter Labs has not disclosed any information about the zkPorter testnet and development progress.

EigenDA

EigenDA is a DA layer project developed based on EigenLayer. Friends who are not familiar with EigenLayer can read the previous article of Insight Weekly "Research Report | EigenLayer: Strengthening Ethereum Security and Inspiring a New Era of Staking".

But fundamentally, unlike general-purpose DA projects such as Celestia and Avail, EigenDA is a middleware that does not have its own consensus mechanism. Its security is obtained through the Ethereum validator re-staking model of EigenLayer.

EigenDA is also the first active verification service (AVS) on EigenLayer. Re-stakers re-stake ETH into EigenDA to perform data verification services in exchange for compensation. Buyers (L2) publish data to EigenDA to obtain lower transaction costs and higher TPS.

Although EigenDA has not yet been launched on the testnet, many teams have plans to integrate EigenDA into their L2, such as Mantle, Layer N, Offshore, etc.

Celestia

Celestia is a general-purpose DA public chain with its own verification nodes and PoS consensus mechanism. Although it is more expensive than other off-chain DA solutions, its security is significantly higher than them.

Celestium is an Ethereum L2 chain that uses Celestia as the DA layer and Ethereum as the settlement and consensus layer.

Celestium implements data availability as shown below:

  • Celestium uploads the proof data (Proofs) to Ethereum as usual, but publishes the transaction data (Transaction Date) to Celestia;

  • The data availability proof is signed by Celestia’s verification node and sent to the DA Bridge Contract deployed on Ethereum for verification and storage;

  • L2 contracts on Ethereum can access it at any time.

Celestia has completed two rounds of financing, including US$1.5 million in the seed round in March 2021 and US$55 million in the second round in October 2022, with the participation of several well-known VCs.

At the same time, the airdrop news released by Celestia on September 26 drew people's attention to the modular blockchain and DA layer track.

According to official information, Celestia will airdrop TIA (Celestia's native asset) to 7,579 developers and 576,653 on-chain addresses. Developers include public products and key protocol infrastructure, Eth Research, and public contributors to DA layer projects (such as Avail, EigenLayer, and Solana). On-chain addresses include active users in Ethereum Rollup, pledgers of Cosmos Hub and Osmosis, and IBC relayers.

Avail

Avail was originally a project founded by Polygon Labs in 2020 to solve the problem of data availability, but in March of this year it separated from Polygon and operated as an independent DA public chain, no longer limited to Polygon or Ethereum.

Technically, it is more complex than Celestia. The mainnet is expected to be launched in the first quarter of 2024, and only the testnet is currently online. The Avail testnet has now entered the second phase, and users can participate in a variety of ways, including:

  • Token acquisition: Users can obtain AVL testnet tokens to explore staking and nomination functions;

  • Blockchain development: Users are free to develop modular blockchain applications or chains that integrate with Avail;

  • Network Roles: Users can choose to join the testnet as a validator or a light client, thereby facilitating the data verification process.

Obviously, compared to L2 interaction, the interaction threshold of DA layer projects is higher, but since Celestia has announced the airdrop, friends who have the conditions can explore the interaction. Avail There is currently a test network incentive activity "Clash of Nodes Challenges"
https://docs.availproject.org/clash-of-nodes/challenges/…

But the conclusion is: running a node is useless, you can't get points. If you want to get points, you have to apply for a validator, which is not easy. Ordinary users are now waiting for new tasks, so you can continue to pay attention.

Summary and Thoughts

In the future roadmap of Ethereum presented by Vitalik in 2022, it is clearly shown that after The Merge, the focus of The Surge to be achieved in the next stage of Ethereum is to further reduce the cost of publishing data for L2 through EIP-4844. This means that Ethereum is only willing to separate the execution layer, and hopes to continue to maintain the functions of the DA layer, settlement layer and consensus layer.

Therefore, it is not difficult to explain why the EIP-4844 proposers and L2BEAT are not inclined to recognize expansion projects that use off-chain DA solutions as L2.

After the Cancun upgrade is officially completed, these off-chain DA layer projects (especially the DA public chain) may face direct business competition with Ethereum. By then, in addition to focusing on lower costs, how will they improve their competitiveness?

Celestia chose to issue coins at this time to incentivize developers and active addresses on the chain, perhaps also with strategic considerations to seize the initiative and win people's hearts. At the same time, for users, it is also worth looking forward to whether big projects like Optimism and Arbitrum will emerge in the future competition at the DA layer.

References:

【1】PSE Trading: A new narrative for modular blockchains - competition among DA layer players

【2】The Ethereum Off-Chain Data Availability Landscape

【3】Intro to EigenDA: Hyperscale Data Availability for Rollups

【4】Proto-Danksharding FAQ

[5] Is there any way to solve Ethereum congestion? zkPorter: A composable Ethereum Layer 2 expansion solution

【6】Quantum Gravity Bridge: Secure Off-Chain Data Availability for Ethereum L2s with Celestia

【7】Volition and the Emerging Data Availability spectrum

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