Arbitrum Orbit with Celestia DA
Overview
The integration of Celestia with Arbitrum Orbit and the Orbit stack marks the first external contribution to the Arbitrum Orbit protocol layer, offering developers an additional option for selecting a data availability layer alongside Arbitrum AnyTrust. The integration allows developers to deploy an Orbit Chain that uses Celestia for data availability.
Learn more about Orbit in Arbitrum's introduction.
Key components
The integration of Celestia with Arbitrum Orbit is possible thanks to 3 key components:
Additionally, the fallback mechanism is a feature of the integration, which is native in Nitro.
DA provider implementation
The Arbitrum Nitro code has a set of daprovider interfaces to perform reads and writes for a given DA layer that are used across the codebase for EIP4844 Blobs, Anytrust, and Celestia DA.
This integration implements the reader and writer interfaces.
Additionally, the logic for reading, writing, and generating Celestia related proofs is moved to a sidecar celestia-server, which allows the Nitro node to request submissions and retrivals from a celestia node using an RPC client.
To run the Celestia server see the nitro-das-celestia repository for more instructions.
Preimage Oracle Implementation
In order to support fraud proofs, this integration has the necessary code for a Nitro validator to populate its preimage mapping with Celestia hashes that then get "unpeeled" in order to reveal the full data for a Blob. You can read more about the "Hash Oracle Trick".
The data structures and hashing functions for this can be found in the nitro/das/celestia/tree directory
You can see where the preimage oracle gets used in the fraud proof replay binary.
Blobstream integration
The integration ensures that in the case of a challenge in which the ReadInboxMessage instruction is disputed, that the corresponding batch can be confirmed to be in Celestia through the use of Blobstream (default is SP1 Blobstream by Succinct), which gives us strong security gaurantees that the data was made available on Celestia.
Fallback mechanism in Nitro
Arbitrum Nitro natively supports the ability to "fallback" to Ethereum DA in case that writing a batch to Anytrust is unsuccessful, the Celestia DA integration goes a step beyond, enabling fallbacks from any dapwriter to another by introducing a da-preference parameter to the node which allows developers to specify in which order they would like to prioritize fallbacks, for example, ["celestia", "anytrust"] indicates the batch poster to first write to celestia, on failure fallback to anytrust, and on failure fallback to ethereum da or "celestia" -> "anytrust" -> "blobs / calldata"
Next steps
Follow the quickstart guide on the next page to run a local nitro chain with Nitro testnode.