SYNOPSIS
This is an implementation of the modified merkle patricia tree as specified in the Ethereum's Yellow Paper:
The modified Merkle Patricia tree (trie) provides a persistent data structure to map between arbitrary-length binary data (byte arrays). It is defined in terms of a mutable data structure to map between 256-bit binary fragments and arbitrary-length binary data. The core of the trie, and its sole requirement in terms of the protocol specification is to provide a single 32-byte value that identifies a given set of key-value pairs.
The only backing store supported is LevelDB through the levelup
module.
INSTALL
npm install merkle-patricia-tree
USAGE
There are 3 variants of the tree implemented in this library, namely: BaseTrie
, CheckpointTrie
and SecureTrie
. CheckpointTrie
adds checkpointing functionality to the BaseTrie
with the methods checkpoint
, commit
and revert
. SecureTrie
extends CheckpointTrie
and is the most suitable variant for Ethereum applications. It stores values under the keccak256
hash of their keys.
Initialization and Basic Usage
import level from 'level'
import { BaseTrie as Trie } from 'merkle-patricia-tree'
const db = level('./testdb')
const trie = new Trie(db)
await trie.put(Buffer.from('test'), Buffer.from('one'))
const value = await trie.get(Buffer.from('test'))
console.log(value.toString())
Merkle Proofs
const prove = await Trie.prove(trie, Buffer.from('test'))
const value = await Trie.verifyProof(trie.root, Buffer.from('test'), prove)
console.log(value.toString())
Read stream on Geth DB
import level from 'level'
import { SecureTrie as Trie } from 'merkle-patricia-tree'
const db = level('YOUR_PATH_TO_THE_GETH_CHAIN_DB')
// Set stateRoot to block #222
const stateRoot = '0xd7f8974fb5ac78d9ac099b9ad5018bedc2ce0a72dad1827a1709da30580f0544'
// Initialize trie
const trie = new Trie(db, stateRoot)
trie
.createReadStream()
.on('data', console.log)
.on('end', () => {
console.log('End.')
})
Read Account State including Storage from Geth DB
import level from 'level'
import rlp from 'rlp'
import { BN, bufferToHex } from 'ethereumjs-util'
import Account from 'ethereumjs-account'
import { SecureTrie as Trie } from 'merkle-patricia-tree'
const stateRoot = 'STATE_ROOT_OF_A_BLOCK'
const db = level('YOUR_PATH_TO_THE_GETH_CHAINDATA_FOLDER')
const trie = new Trie(db, stateRoot)
const address = 'AN_ETHEREUM_ACCOUNT_ADDRESS'
const data = await trie.get(address)
const acc = new Account(data)
console.log('-------State-------')
console.log(`nonce: ${new BN(acc.nonce)}`)
console.log(`balance in wei: ${new BN(acc.balance)}`)
console.log(`storageRoot: ${bufferToHex(acc.stateRoot)}`)
console.log(`codeHash: ${bufferToHex(acc.codeHash)}`)
let storageTrie = trie.copy()
storageTrie.root = acc.stateRoot
console.log('------Storage------')
const stream = storageTrie.createReadStream()
stream
.on('data', (data) => {
console.log(`key: ${bufferToHex(data.key)}`)
console.log(`Value: ${bufferToHex(rlp.decode(data.value))}`)
})
.on('end', () => {
console.log('Finished reading storage.')
})
API
TESTING
npm test
REFERENCES
- Wiki
- Blog posts
- Videos
EthereumJS
See our organizational documentation for an introduction to EthereumJS
as well as information on current standards and best practices.
If you want to join for work or do improvements on the libraries have a look at our contribution guidelines.
LICENSE
MPL-2.0