Next-Gen DA for Ethereum L2s: ZK-Powered Blobstream
Article1,098 words
Explains how Blobstream attests Celestia data to Ethereum L2s versus data availability committees, and how ZK versions from Succinct and RISC Zero cut overhead. Blobspace starts at 8MB per block, roughly 9,000 to 30,000 ERC-20 TPS.
Key claims
Blobstream updates in batches of about 400 blocks, roughly every 100 minutes
8MB blocks translate to 9,000 to 30,000 ERC-20 TPS
Contract requires signatures from 2/3 of Celestia stake
Next-Gen DA for Ethereum L2s: ZK-Powered Blobstream
Data availability has long been the primary scaling bottleneck for Ethereum rollups. With Blobstream finally live on mainnet and ZK-powered implementations already on the way, this is history.
Let me walk you through this game-changing piece of technology for the Ethereum L2 ecosystem and explain why you should be even more excited about zkVM-based Blobstream implementations like the one @RiscZero is cooking up.
Ready for alpha anon?
What is Celestia?
@CelestiaOrg is a modular data availability layer implemented as a purpose-built L1 on the Cosmos SDK and running a CometBFT-based PoS consensus protocol.
It leverages cutting-edge technologies such as data availability sampling light nodes to provide an abundance of block space to rollups that need a scalable base layer to publish transaction data to.
What is Blobstream?
Blobstream is the first data availability solution (built on @CelestiaOrg) for Ethereum that securely scales with its user base.
Previously known as the Quantum Gravity Bridge, Blobstream relays commitments from Celestia's data root to an on-chain light client on Ethereum, allowing developers to integrate these into L2 contracts.
This empowers Ethereum developers to build high-throughput L2s using Celestia's optimized DA layer.
Any ecosystem can simply deploy a Blobstream light client on-chain to enable L2s and L3s to securely publish data to Celestia.
Why does Blobstream matter?
While EIP-4844 has significantly lowered on-chain data cost for Ethereum-based rollups, it is still more expensive than using off-chain alternatives such as a more centralized data availability committee (DAC) that guarantees to make the data available.
However, these come with certain tradeoffs. Blobstream aims to overcome those and provide a more decentralized, secure and scalable framework for rollup DA.
Decentralization and Security
Blobstream relies on Celestia's CometBFT-based proof-of-stake system, sharing Celestia's security guarantees. In contrast, Data Availability Committees (DACs) are often centralized, relying on specific off-chain entities or individuals for DA.
Mechanism of Verification
Blobstream confirms data presence on Celestia through data availability attestations, which are Merkle roots of batched L2 data. Ethereum L2 contracts can directly verify data publication with Blobstream. DACs, however, depend on attestations or confirmations from their permissioned members.
Flexibility and Scalability
Blobstream offers high-throughput data availability for Ethereum L2s, independent of Ethereum's gas costs, focusing on byte-based resource pricing for enhanced scalability. The scalability and flexibility of DACs vary based on their specific design and implementation.
Weren't there L2s that used Celestia before Blobstream?
Yes anon.
But let me explain what the difference is.
In summary: If the DA Blobstream bridge is not utilized, Ethereum lacks the capability to verify if data has been posted to Celestia. This assertion, made by an unidentified DAC, may not be associated with Celestia Validators.
In a scenario where the Sequencer, DAC members, and Prover conspire, your assets could potentially be indefinitely immobilized in this setup, as reconstructing the rollup's state independently would be impossible.
The positive aspect is that, due to the use of validity proofs, assuming the soundness of the proof system, it is not possible for them to post an invalid state and misappropriate the funds.
How does Blobstream work?
An Ethereum-based L2 using Blobstream “settles” any fraud or ZK proofs to Ethereum and publishes its transaction data to Celestia.
This contrasts with the typical rollup model of e.g. Arbitrum One or OP Mainnet, which both settle proofs and post their transaction data on Ethereum.
Although L2s using Blobstream do rely on correct attestations from Celestia validators, light nodes can detect if 2/3 of Celestia validators have behaved maliciously by withholding data, and slash them.
While not as completely trust-minimised as fully onchain DA, this does provide crypto-economic security guarantees that do not exist with DACs.
Blobstream uses a light client relay to submit commitments to Celestia’s data root to an Ethereum smart contract. The Blobstream smart contract enforces that every commitment has ECDSA signatures from validators representing at least 2/3s of the stake on Celestia.
The Celestia validators sign over all of the Celestia block data. This means that any user can prove inclusion to any data included on Celestia via the Blobstream contracts with Merkle proofs.
How scalable is Blobstream?
Blobstream allows L2s to access @CelestiaOrg’s blob space, which can initially be up to 8 MB per block on Mainnet Beta, upgradeable via onchain governance.
Depending on the compression scheme, 8 MB of blobspace roughly translates to between 9,000 and 30,000 ERC-20 transfer transactions per second. Thanks to DAS, Celestia's blobspace can securely scale to future demand as the number of sampling light nodes increases.
ZK-powered Blobstream
Blobstream X
Currently, Blobstream verifies @CelestiaOrg's consensus by verifying ECDSA signatures from Celestia validators in the Ethereum contract.
This occurs in batches of about 400 blocks (once every ~100 minutes).
@SuccinctLabs has been developing an implementation of Blobstream that uses zero-knowledge proofs to verify Celestia’s validator EdDSA signatures on Ethereum.
Blobstream X is also live today on testnet (see above) and has several exciting benefits:
Reduced overhead
Blobstream X simplifies the infrastructure required by @CelestiaOrg validators, eliminating the need for special-case logic for Ethereum attestations using ECDSA. This enhancement optimizes @CelestiaOrg as a high-throughput blockchain with verifiable data availability.
ZK-proving beyond consensus
’s consensus. While still in early stages, it could eventually verify aspects like Celestia’s block validity rules (e.g., erasure encoding) and its (tiny) state machine. This reduces the need for end users to trust Celestia’s validator set.Blobstream X paves the way for proving more than just@CelestiaOrg
Request/response model
Optimal contract updates with a request/response model enable Blobstream to update commitments onchain faster than the typical ~100 minutes, allowing for on-demand updates.
Gas savings
Significant gas savings for the relayer, as Blobstream’s ZK proofs can be aggregated with others.
Blobstream Zero
Another industry-leading ZK team that is working with @CelestiaOrg on a Blobstream implementation is @RiscZero.
Blobstream Zero is a next-generation zkVM-based Blobstream bridge that will open up a world of possibilities for the modular ecosystem by bridging Celestia’s modular data availability layer to Ethereum, @Optimism, Bitcoin, @Solana, and more.
With this bridge, rollups and applications can ZK prove and verify the validity of @CelestiaOrg’s data availability (DA) on any chain, cheaper and faster than ever before.
It also opens up a completely new class of modular applications: ZK Coprocessors. This means that dApps on Ethereum, @Optimism, and @Solana can run highly functional and data-rich ZK programs, powered by @RiscZero and Celestia, while maintaining composability with the chain.
The code of Blobstream Zero will be fully open-sourced and permissionless. The Rust-based repository will be easily upgradable and extensible, thanks to the zkVM foundations, allowing projects to modify the bridge to fit their needs.
x.com/CelestiaOrg/status/1800196683030298886
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