Writing: EigenLabs

Compilation: Deep Tide TechFlow

EigenDA is a secure, high-throughput, and decentralized data availability (DA) service built on Ethereum, using EigenLayer's re-staking basic module. Developed by EigenLabs, EigenDA will be the first active validation service (AVS) launched on EigenLayer. Once launched, restakers will be able to delegate staking rights to node operators performing validation tasks for EigenDA in exchange for service payments, and Rollup will be able to publish data to EigenDA for lower transaction costs, higher transaction throughput, and security composability within the EigenLayer ecosystem. The security and throughput design can scale horizontally with the number of restakers and operator selection to provide services for the protocol.

We hope that EigenDA will contribute to the Ethereum ecosystem in the following ways:

• Provide innovative DA solutions for Rollup to contribute to Ethereum's ultimate goal of scalability and obtain security and value from Ethereum stakers and validators. EigenDA is built on some core ideas and libraries that are key upgrades to Danksharding and can be tested in practical applications of these technologies.

• Provide high throughput and low-cost standards to promote the growth of new on-chain application use cases. EigenDA will support applications such as multiplayer games, social networks, and video streaming with a flexible cost model, including variable and fixed fees.

• Protect decentralized key elements. In a shared security system like EigenLayer, if every node operator needs to download and store every chain using the system, few node operators can keep up, potentially leading to centralization. EigenDA is designed to prevent this centralization trend by distributing work among many participating nodes, achieving high performance, and requiring each operator to complete only a small amount of work.

• Prove the power of programmable trust. EigenDA aims to demonstrate that Ethereum stakers and validators can support critical Ethereum infrastructure. In addition to Ethereum consensus, AVS (such as EigenDA) and AVS users (such as Rollup using EigenDA) can successfully implement new business and token models on a modular basis within the Ethereum trust network.

We are pleased to see several teams planning to integrate EigenDA into their L2 infrastructure, including: Celo transitioning from L1 to Ethereum L2; Mantle and its range of complementary products in the BitDAO ecosystem; Fluent providing zkWASM execution layer; Offshore providing Move execution layer; Layer N providing zk-OP hybrid Rollup for financial applications, and more.

Technical Architecture

The following diagram shows the basic process of data in EigenDA.

The Rollup Sequencer creates blocks with transactions and sends requests to disperse data blocks.

The Disperser is responsible for encoding data blocks into chunks using erasure coding, generating KZG commitments and KZG multi-reveal proofs, and sending the commitments, blocks, and proofs to the operational nodes of the EigenDA network.

Rollup can run its own Disperser or use a third-party (such as EigenLabs) for dispersal services to facilitate and share the cost of signature verification. When the service is unresponsive or under review, Rollup can use its own Disperser as a backup to benefit from cost sharing without sacrificing review resistance.

EigenDA nodes use multi-reveal proofs to verify the received blocks against KZG commitments, persist the data, and then generate and return signatures to the Disperser for aggregation.

Technical Considerations

Now that we have a basic understanding of EigenDA's architecture, let's discuss the benefits and features that the system aims to achieve. Here is a brief list of some essential features that we believe are necessary for a good and useful data availability layer for Rollup:

• Cost-effectiveness
• Throughput
• Security
• Customizability

We will explain each feature from EigenDA's perspective.

Cost-effectiveness

Today, many L2s use Ethereum as their data availability layer because it provides cryptographic economic security guarantees. This results in high and volatile costs as Rollup competes for limited block space with all other Ethereum users, based on congestion pricing. For example, Arbitrum and Optimism have spent tens of millions of dollars on Ethereum's data availability fees this year, with no consistency month to month. One of the main value propositions of a data availability system is to significantly reduce these costs and provide greater predictability in cost structure for Rollup.

Cost Reduction

Operating a data availability system incurs costs in three basic dimensions. Let's analyze how EigenDA minimizes the underlying cost structure in each dimension:

Cost of staked capital. To secure the data availability layer, restakers may want to earn a certain proportion of returns to offset their opportunity costs. EigenDA reduces the cost of staked capital by using EigenLayer, which adopts a shared security model, allowing the same staking to be shared across various applications, creating economies of scale.

Operating costs. EigenDA does not require each node to download and store all data. Instead, it uses erasure coding to split the data into smaller chunks and requires operators to download and store only a single chunk, which is a fraction of the full data block size. This reduces the cost for each operator compared to storing complete data blocks, enabling many nodes to operate EigenDA in a "lightweight" manner. As more nodes join the EigenDA network, the resource costs per node on the network also decrease. This allows EigenDA to be provided at a lower cost by a large number of operators, achieving gradual cost reduction and promoting abundance rather than scarcity.

Congestion costs. When the bandwidth utilization of any blockchain approaches system capacity, the cost of data begins to rise. EigenDA reduces congestion in two ways: 1. By aiming for higher throughput, it seeks to make congestion a rare occurrence; 2. By allowing bandwidth reservations, EigenDA can guarantee reserved throughput for Rollup at discounted prices. To maintain flexibility, EigenDA also allows Rollup to pay for throughput on demand.

Rollup Economics

The economics of Rollup are fundamentally different from L1 because data availability costs are not only high and unpredictable but also paid in non-native tokens. This makes it difficult for Rollup to make price commitments to users and subsidize initial adoption, as they must bear the "exchange rate risk" between their own Rollup token and the token used to pay data availability fees. In contrast, L1 pays a fixed amount of inflation and can offer a certain number of free transactions per second to attract users.

EigenDA is exploring ways to enable Rollup to pay stakers in native Rollup tokens at a predictable long-term reservation rate, under terms recognized by EigenLayer stakers. This combines the inherent scale advantages of a shared security system with the stability of payment in native tokens to help drive the use of Rollup.

Throughput

Throughput is another fundamental value proposition of a data availability system. EigenDA aims to achieve horizontal scalability, where the more operators on the network, the greater the throughput. In private testing with 100 nodes exhibiting standard performance characteristics, EigenDA has already demonstrated throughput of up to 10 MBps and plans to scale to 1 GBps. This opens the door for bandwidth-intensive applications on Ethereum, such as multiplayer games and video streaming.

EigenDA achieves high throughput through three pillars in its design:

Decoupling DA from consensus. Existing DA systems combine proofs of data blob availability with the ordering of data blobs into an "integrated" architecture. While proofs of data availability can be done in parallel as nodes can independently prove the availability of different data blocks, ordering requires serialization of data blocks, leading to significant consensus lag. While this coupling may be beneficial for systems designed as the ultimate source of ordering for security, it is neither necessary nor useful for DA systems designed to be used in conjunction with the Ethereum blockchain, which already has a sorting system for settlement. By simplifying the unnecessary complexity of ordering and designing a pure DA system, EigenDA has made significant improvements in throughput and latency.

Erasure coding. EigenDA allows Rollup to break down data to be published to EigenDA into smaller blocks and apply erasure coding to these blocks before storing the data. Using KZG polynomial commitments (the core mathematical scheme of ZK proofs), EigenDA only needs to download a small amount of data instead of the entire data block. Unlike systems that use fraud proofs to detect malicious error coding, EigenDA adopts effective proofs of validity in the form of KZG commitments, enabling nodes to verify the correct coding of data.

Direct communication instead of P2P. Existing DA solutions use peer-to-peer (P2P) network to transmit data blocks, where operators receive data blocks from their peers and then rebroadcast the same data blocks to others. This severely limits the achievable DA rate. In EigenDA, the Disperser directly sends data blocks to operators of EigenDA. By relying on direct communication to disperse data, EigenDA can confirm DA through native network latency. This eliminates significant gossip penalties from P2P and leads to faster data commitment times.

Security Features

We consider security as an umbrella term covering security and liveness, as well as decentralization and censorship resistance. The following features demonstrate the security of EigenDA:

EigenLayer. By using re-staking, EigenDA borrows two different security aspects from the EigenLayer system: 1. Economic security; 2. Decentralization. EigenDA is designed to collaboratively leverage these two different trust elements from EigenLayer and the Ethereum ecosystem in a synergistic manner.

Hosting proof. A key failure mode for operators in EigenDA is nodes signing data items without actually storing the required data. To address this issue, EigenDA uses a mechanism called hosting proof, initially proposed by Justin Drake and Dankrad Feist of the Ethereum Foundation. With hosting proof, each operator must regularly compute and commit to the value of a function that can only be computed when they have stored the allocated data block. If they prove the data block before computing this function, anyone with access to their data items can slash the ETH held by the node.

Dual arbitration model. EigenDA also features a function called dual arbitration, where two independent arbitrators can be requested to prove the availability of data. For example, one arbitrator can consist of ETH restakers (ETH quorum), and the second arbitrator can consist of restakers of the native token of the rollup.

Censorship resistance. Compared to coupled DA layers, EigenDA provides higher instantaneous censorship resistance. This is because coupled DA architectures typically rely on a single leader or block proposer to linearly order data blocks, creating an instantaneous censorship chokepoint. In contrast, in EigenDA, rollup nodes can disperse and receive signatures directly from the majority of EigenDA nodes, thereby elevating censorship resistance to the majority of EigenDA nodes, rather than being limited to a single leader.

Security Analysis

As discussed earlier, EigenDA is based on ETH staking through EigenLayer and built using erasure coding with configurable encoding rates set by the rollup. Security analysis for blockchain systems like EigenDA has three different perspectives; we describe each perspective and how it applies to the above EigenDA:

Byzantine Fault Tolerance (BFT): Assuming some nodes are honest and fully compliant with the protocol, while others are malicious and can deviate from the protocol arbitrarily.

EigenDA is secure, meaning data retrieval is possible as long as X% of nodes are honest, where X can range from 10% to 50%, depending on the encoding rate.

Nash Equilibrium Model: Analyzing the economic incentives for each node or small colluding nodes to comply with the protocol, assuming independent behavior of nodes among different colluding nodes.

As long as the collusion scale is less than (1-X), storing and providing data to users is a Nash equilibrium: storing data is guaranteed through storage proof as a balance, and the ETH of nodes storing data will be slashed; providing data is guaranteed by dispersing data to many nodes, creating a competitive market to provide data.

Pure Cryptoeconomic Model: Assuming all stakes are held by the same node and modeling the cost of economic corruption.

As long as data is available, or in other words, as long as X% of nodes are honest, any node not hosting data will have its staked ETH slashed. However, EigenDA does not have unconditional cryptoeconomic security; if all nodes collude and conceal data, they may not be slashable. In the dual arbitration model described earlier, even if ETH cannot be slashed, rollup can slash the native token when staked alongside ETH.

As we can see, EigenDA is built on a trust model that requires not only economic trust from ETH staking but also decentralization and independence of operators to operate securely. Fortunately, EigenLayer allows EigenDA to borrow both of these trust mechanisms from Ethereum.

Customizability

Rollup developers can implement a flexible EigenDA and adjust parameters as needed. The modular nature of EigenDA allows rollup to customize security/liveness trade-offs, staking token models, erasure coding, accepted payment tokens, and more.

As discussed in the previous section, some of the most important flexible decisions in EigenDA are economic decisions. For example, rollup can choose to use dual arbitration staking, where their own tokens are staked to ensure data availability; or rollup can choose an on-demand or reservation cost structure.

Strategic Considerations

Finally, we believe that EigenDA provides strategic value for rollup beyond its technical attributes.

Ethereum's stakers and validators are the driving force behind EigenLayer and therefore also the driving force behind EigenDA. By adopting EigenDA, Rollup can align with these Ethereum stakeholders, who value decentralization, censorship resistance, open-access software, and composable, permissionless innovation.

EigenDA plans to be one of the first of many AVSs launched in the EigenLayer ecosystem. We anticipate that as the number of AVSs grows, there will be combinatorial benefits among them, benefiting the end users of AVS, and we expect these users to include various types of Rollup. For example, following EigenDA, we expect to see AVSs with use cases such as ordering, fast confirmations, monitoring networks, bridging, fair ordering, and even artificial intelligence.

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