Dock SDK Tutorial

Graphical Anchoring Utility

You can also anchor without touching any code. Visit https://fe.dock.io/#/anchor/batch for creation of anchors and https://fe.dock.io/#/anchor/check for anchor verification.

To Batch, or not to Batch

Batching (combining multiple anchors into one) can be used to save on transaction costs by anchoring multiple documents in a single transaction as a merkle tree root.

Batching does have a drawback. In order to verify a document that was anchored as part of the batch, you must provde the merkle proof that was generated when batching said file. Merkle proofs are expressed as .proof.json files and can be downloaded before posting the anchor. No merkle proof is required for batches containing only one document.

Programatic Usage

The on-chain anchoring module allows to developers the flexibility talor anchors to their own use-case, but the sdk does provide a reference example for batching and anchoring documents.

The anchoring module is hashing algorithm and hash length agnostic. You can post a multihash, or even use the identity hash; the chain doesn't care.

One thing to note is that rather than storing your anchor directly, the anchoring module will store the blake2b256 hash of the anchor. This means as a developer you'll need to perform an additional hashing step when looking up anchors:

// pseudocode

function postAnchor(file) {
  anchor = myHash(file)
  deploy(anchor)
}

fuction checkAnchor(file) {
  anchor = myHash(file)
  anchorblake = blake2b256(anchor)
  return lookup(anchorblake)
}

See the example/anchor.js in the sdk repository for more info.