debug_preimage | Arbitrum

POST /66f812de2a6724a75a51f60dd6f2a154

debug_preimage

cURL

curl --request POST \
  --url https://nd-954-882-037.p2pify.com/66f812de2a6724a75a51f60dd6f2a154 \
  --header 'Content-Type: application/json' \
  --data '
{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "debug_preimage",
  "params": [
    "0x0000000000000000000000000000000000000000000000000000000000000000"
  ]
}
'

200

{
  "jsonrpc": "<string>",
  "id": 123,
  "result": "<string>"
}

Arbitrum API method that returns the preimage for a given Keccak-256 hash. In Ethereum’s state trie, account addresses are stored as their Keccak-256 hashes. This method allows retrieving the original data (preimage) that was hashed. The node must have preimage recording enabled for this method to return results.

Learn how to deploy a node with the debug and trace API methods enabled.

This method is available for post-Nitro blocks only (block 22,207,815 and later). For pre-Nitro blocks, use the arbtrace_* methods instead.

Preimage recording must be enabled on the node (--cache.preimages). If preimages are not stored, this method returns an error.

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Parameters

• hash — the Keccak-256 hash to look up the preimage for, encoded as a hex string.

Response

• data — the raw preimage bytes as a hex string. Returns an error if the preimage is not found.

debug_preimage code examples

ethers.js

const ethers = require('ethers');
const NODE_URL = "YOUR_CHAINSTACK_ENDPOINT";
const provider = new ethers.JsonRpcProvider(NODE_URL);

const debugPreimage = async (hash) => {
  const result = await provider.send("debug_preimage", [hash]);
  console.log(result);
};

debugPreimage("0x0000000000000000000000000000000000000000000000000000000000000000");

Use case

The debug_preimage method is useful for resolving Keccak-256 hashes back to their original values. In the state trie, account addresses and storage keys are stored as hashes. This method allows developers building state analysis tools to reverse-lookup hashes to their original addresses or data, which is essential for tools like state diff visualizers and trie explorers.

Body

application/json

id · integer · default: 1

jsonrpc · string · default: 2.0

method · string · default: debug_preimage

params · string[]

The Keccak-256 hash to look up the preimage for.

Response

200 - application/json

Returns the preimage for the given hash.

jsonrpc · string

id · integer

result · string