In-depth Discussion on Data Availability Solutions

In the field of blockchain, data availability (DA) has always been an important challenge faced by Layer 2, mainly reflected in the trade-off between security and cost. To address this issue, the industry has proposed two different solutions: on-chain and off-chain.

On-chain solution: Proto-Danksharding

On-chain solutions refer to L2 continuing to use Ethereum as the DA layer, relying on Ethereum to reduce data availability costs. Proto-Danksharding(EIP-4844) is an important solution for Ethereum to lower DA costs. It introduces a new Blob transaction format that allows L2 to perform non-permanent storage in the Ethereum consensus layer in the form of Blobs, thus providing a more economical data availability option for L2.

This means that Ethereum will play the role of a real-time bulletin board in the future, where data on the bulletin board will be deleted after a certain period, and L2 will need to store all data backups on its own. Proto-Danksharding is expected to be implemented in the Ethereum Cancun upgrade at the end of this year.

Off-chain Solutions

Off-chain solutions no longer rely on Ethereum as the DA layer, but seek more economical ways of data availability. Depending on the level of decentralization and security, off-chain solutions can be divided into four categories:

Validium

Validium is a highly centralized DA solution. Transaction data is managed by centralized operators and published off-chain. While this greatly reduces DA costs and protects transaction privacy, it also brings higher security risks. If the operator fails or acts maliciously, user funds may be irretrievable.

Data Availability Committee ( DAC )

To reduce the risks associated with a single operator, most Validium solutions are accompanied by DAC. DAC is similar to a consortium blockchain, consisting of multiple trusted nodes that preserve copies of transaction data and make data public when necessary. Although the operating costs are low, small-scale DACs still face the risk of private keys being stolen or collective malpractice.

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. Users can move assets to an off-chain account for frequent low-cost transactions when needed, and then move them back to an on-chain account after the transactions are completed. Compared to pure Validium, Volition can inherit part of Ethereum's security.

Universal DA Solution

In addition to solutions within the Ethereum ecosystem, there is also a type of general-purpose DA solution that can not only provide data availability for Ethereum L2 but also serve more chains and projects. These solutions typically have independent validation nodes, block producers, and consensus mechanisms, but do not support smart contracts.

Overview of DA Layer Projects

Under the framework of modular blockchain, Ethereum has almost monopolized the consensus layer and settlement layer, and the execution layer is also gradually forming an oligopoly. In contrast, the DA layer is still in its infancy, and here are a few DA layer projects worth paying attention to:

StarkEx

StarkEx is a scalability solution framework developed by the StarkWare team, providing DA solutions for specific applications. It supports three data availability modes: on-chain, Validium, and Volition. The Validium solution of StarkEx combines DAC to enhance security. Currently, several well-known projects are using StarkEx to provide data availability services.

zkPorter

zkPorter is an off-chain data availability solution proposed by the zkSync team at Matter Labs. It is an independent chain specifically designed for L2 to publish transaction data, maintaining security through PoS consensus. zkSync token holders can stake their tokens to become guardians of zkPorter, participating in the validation and signing of blocks. However, although zkPorter has been proposed for some time, there is currently no clear development progress information.

EigenDA

EigenDA is a DA layer project developed based on EigenLayer. Unlike other general-purpose DA projects, EigenDA is a middleware that does not have an independent consensus mechanism; its security comes from the restaking model of Ethereum validators on EigenLayer. EigenDA is the first proactive verification service (AVS) on EigenLayer. Although it has not yet launched on the testnet, several teams have already planned to integrate it into their own L2s.

Celestia

Celestia is a general-purpose DA public chain, featuring independent validation nodes and a PoS consensus mechanism. Compared to other off-chain DA solutions, Celestia, while having a higher cost, significantly enhances security. Celestium is an L2 chain that uses Celestia as the DA layer and Ethereum as the settlement and consensus layer. Celestia has completed two rounds of financing and recently announced a token airdrop plan, attracting industry attention to modular blockchains and DA layers.

Avail

Avail was originally a project under Polygon Labs and has been operating as an independent DA public chain since March of this year. In terms of technical implementation, it is more complex than Celestia, with the mainnet expected to launch in the first quarter of 2024. Currently, Avail has entered the second phase of its testnet, and users can participate in various ways, including obtaining testnet tokens, developing integrated applications, serving as network validators, or light clients.

Conclusion

The future roadmap of Ethereum indicates that reducing data publishing costs for L2 through EIP-4844 is a key focus for the next phase. This means that Ethereum aims to retain the functionalities of the DA layer, settlement layer, and consensus layer, only separating the execution layer. Therefore, it is disputed whether projects using off-chain DA solutions can still be considered L2.

After the upgrade in Cancun is completed, off-chain DA layer projects may directly face business competition with Ethereum. In addition to cost advantages, these projects also need to explore other ways to enhance their competitiveness. For users, it is worth looking forward to whether significant projects similar to Optimism and Arbitrum will emerge in the DA layer competition.