Elydora Epoch Root (EER)

The EER is a periodic Merkle root that anchors all operations within a time window into a single verifiable hash, signed by Elydora.

Structure

Field	Type	Required	Description
epoch_id	string	Yes	Unique identifier for this epoch.
org_id	string	Yes	Organization identifier.
start_time	string	Yes	ISO 8601 start of the epoch time window.
end_time	string	Yes	ISO 8601 end of the epoch time window.
leaf_count	number	Yes	Number of operations included in this epoch.
root_hash	string	Yes	SHA-256 Merkle root of all operation hashes in the epoch.
hash_alg	string	Yes	Hash algorithm used. Currently SHA-256.
signature_by_elydora	string	Yes	Ed25519 signature by Elydora over the epoch root.

Example EER

json

{
  "epoch_id": "epoch_001",
  "org_id": "org_acme",
  "start_time": "2026-02-28T00:00:00Z",
  "end_time": "2026-02-28T06:00:00Z",
  "leaf_count": 1247,
  "root_hash": "sha256:merkle_root_abc123...",
  "hash_alg": "SHA-256",
  "signature_by_elydora": "base64:elydora-epoch-sig..."
}

Merkle Tree Construction

The Merkle tree is built from the receipt hashes of all operations submitted during the epoch window:

Leaves are the receipt_hash values from each EAR, sorted by seq_no.
Internal nodes are computed as SHA-256(left || right).
If the leaf count is odd, the last leaf is duplicated to complete the tree.

Verification

To verify that a specific operation is included in an epoch:

Obtain the operation's EAR and its receipt_hash
Request a Merkle proof from the API
Recompute the root hash using the proof path
Compare with the EER's root_hash
Verify Elydora's signature over the epoch root using the JWKS

Epoch Timing

Epochs are closed on a configurable schedule (default: every 6 hours). The epoch boundary is based on server_received_at timestamps, not client-side issued_at.