What data availability means for EDMA
Data availability is the property that makes a rollup auditable. If you can't reconstruct the L2 state from data posted to Ethereum, you can't verify the L2's history independently, and a malicious operator could in principle hide things. Without DA, an optimistic rollup's challenge mechanism doesn't even work; you need the data to construct a fraud proof.
EDMA splits the world cleanly. Facts that move money go on-chain: PoV hashes, EMT mints, Locked-to-Unlocked EDSD deltas, fee lines with burn hashes, One-Claim map updates. They live in EIP-4844 blobs posted to Ethereum every 2 to 10 minutes. Big documents, photos, telemetry, customs files, anything with PII, live in evidence vaults off-chain, with their content hashes anchored on L1.
That split is non-negotiable. Putting raw PDFs on a blockchain is privacy malpractice and economically infeasible at scale. Putting only the receipt of an event on-chain (without the evidence behind it) is no better than a press release. The bridge is hash equality: the contract checks that a hash on-chain matches the hash of a file off-chain, and an authorised viewer can pull the file to verify.
How an auditor walks the chain
- 01
Pull batch indices from L1
Every EDMA batch is posted to Ethereum with a known batch index. An auditor queries Ethereum directly (no EDMA API needed) to enumerate the batches relevant to an order, listing, or time range.
- 02
Fetch the blobs
Each batch has an associated EIP-4844 blob containing the PoV hashes, EMT ids, Locked-Unlocked deltas, fee lines, and burn hashes. Blobs are publicly available on Ethereum for ~18 days; archive nodes preserve them indefinitely. The auditor downloads them.
- 03
Verify commitments and deltas
From the blob data, the auditor reconstructs the L2 state transitions. PoV hashes are matched against EMT ids; EDSD deltas are checked against fee lines and burn hashes. Everything is cryptographically verifiable; no EDMA cooperation is needed.
- 04
Request evidence by hash
If the auditor is an authorised role (regulator, internal audit, compliance), they request the underlying file from the EDMA vault using the on-chain hash. The vault serves a short-lived signed URL; the file is downloaded; the auditor re-computes the hash to confirm equality.
- 05
End-to-end proof
Evidence file → PoV hash → EMT mint → EDSD release → burn hash. Every step is independently verifiable, and the chain holds the binding commitments. The auditor never has to trust the EDMA UI or take EDMA's word for anything.
