To submit data to EthDA, users submit blob transactions similar to blob-carrying-transactions introduced by EIP-4844. EthDA blob transactions contain two component, a standard ethereum regular transaction with blob commitments and one or more blobs of data.

Upload Blobs

Step 1: Encode data to blobs

Encode raw data to blobs and compute KZG commitments, KZG proofs and versioned hashes.

For a Node.js implementation, please refer to ethda-blobs.

Step 2: Query blob storage fee

Users could use the same execution api added by EIP-4844 to query the base fee per blob in wei, represented as a hexadecimal:

eth_blobBaseFee

Step 3: Construct and sign regular transactions

to

Should be the DASAddress contract.

value

Blobs storage fee. The calculation formula is:

$value = (Size_{blobs} * Params_{BlobTxBlobGasPerBlob}) * blobBaseFee * multiplier$

where:

• $(Size_{blobs} * Params_{BlobTxBlobGasPerBlob}) * blobBaseFee$ is the base fee, and $priorityFee$ is adjusted by the market, and user could set it to, like 10% of the base fee
• $Size_{blobs}$ means blob count carried by the blob transanction
• $Params_{BlobTxBlobGasPerBlob}$ is the BlobTxBlobGasPerBlob param value of Geth, which is 131072
• $blobBaseFee$ could be queried via eth_blobBaseFee
• $multiplier$ is usually set to 1. To ensure successful transactions during network fluctuations, it can be adjusted as needed.

For a golang implementation, please refer to blob-utils.

data

{
  originator,
  description,
  content_type,
  extra,
  blobs: [
    {
      content_type,
      versioned_hash,  // required
      kzg_commitment, // required
      kzg_proof // required
    },
    {...}
    ...
  ]
}

Step 4: Send blob transaction & blobs

{
  to,
  value,
  data,
  signature,
  blobs,
  blobVersionedHashes,
  kzgCommitments,
  kzgProofs
}

Step 5: Query transaction status

After a blob transaction described above is submitted, users could then monitor transaction status. If transaction is successfully minted, it means specified blobs are successfully stored by EthDA's DAS network.

Download Blobs

Blobs could be download via regular eth_getTransactionByHash / eth_getTransactionByBlockHashAndIndex / eth_getTransactionByBlockNumberAndIndex RPC interfaces.