merkle-patricia-tree

What is merkle-patricia-tree?

The merkle-patricia-tree npm package is a JavaScript implementation of the Ethereum modified Merkle Patricia Trie. It is used to store key-value pairs in a way that allows for efficient verification of the inclusion and integrity of data. This is particularly useful in blockchain applications where data integrity and proof of inclusion are critical.

What are merkle-patricia-tree's main functionalities?

Creating a Trie

This feature allows you to create a new instance of a Merkle Patricia Trie. The Trie can then be used to store and manage key-value pairs.

const { BaseTrie: Trie } = require('merkle-patricia-tree');
const trie = new Trie();

Inserting Data

This feature allows you to insert key-value pairs into the Trie. The keys and values are stored as Buffers.

const { BaseTrie: Trie } = require('merkle-patricia-tree');
const trie = new Trie();
trie.put(Buffer.from('key1'), Buffer.from('value1'), (err) => {
  if (err) throw err;
  console.log('Data inserted');
});

Retrieving Data

This feature allows you to retrieve the value associated with a given key from the Trie.

const { BaseTrie: Trie } = require('merkle-patricia-tree');
const trie = new Trie();
trie.put(Buffer.from('key1'), Buffer.from('value1'), (err) => {
  if (err) throw err;
  trie.get(Buffer.from('key1'), (err, value) => {
    if (err) throw err;
    console.log('Retrieved value:', value.toString());
  });
});

Deleting Data

This feature allows you to delete a key-value pair from the Trie.

const { BaseTrie: Trie } = require('merkle-patricia-tree');
const trie = new Trie();
trie.put(Buffer.from('key1'), Buffer.from('value1'), (err) => {
  if (err) throw err;
  trie.del(Buffer.from('key1'), (err) => {
    if (err) throw err;
    console.log('Data deleted');
  });
});

Proving Inclusion

This feature allows you to create a proof that a particular key-value pair is included in the Trie.

const { BaseTrie: Trie } = require('merkle-patricia-tree');
const trie = new Trie();
trie.put(Buffer.from('key1'), Buffer.from('value1'), (err) => {
  if (err) throw err;
  trie.createProof(Buffer.from('key1'), (err, proof) => {
    if (err) throw err;
    console.log('Proof:', proof);
  });
});

Other packages similar to merkle-patricia-tree

merkle-tree

The merkle-tree package provides a simple implementation of a Merkle Tree, which is a binary tree used for data verification. Unlike the merkle-patricia-tree, it does not support the Patricia Trie structure, which is more efficient for certain types of key-value storage and retrieval.

merkle

The merkle package is another implementation of a Merkle Tree. It is designed for general-purpose use and does not include the Patricia Trie optimizations found in merkle-patricia-tree. It is simpler but less efficient for large datasets.

merkle-tools

The merkle-tools package provides utilities for creating and managing Merkle Trees. It includes features for creating proofs and verifying data integrity, similar to merkle-patricia-tree, but it does not implement the Patricia Trie structure.

README

SYNOPSIS

or #ethereumjs on freenode

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.
- Ethereum's yellow paper

The only backing store supported is LevelDB through the levelup module.

INSTALL

npm install merkle-patricia-tree

USAGE

Initialization and Basic Usage

var Trie = require('merkle-patricia-tree'),
level = require('level'),
db = level('./testdb'),
trie = new Trie(db);

trie.put('test', 'one', function () {
  trie.get('test', function (err, value) {
    if(value) console.log(value.toString())
  });
});

Merkle Proofs

Trie.prove(trie, 'test', function (err, prove) {
  if (err) return cb(err)
  Trie.verifyProof(trie.root, 'test', prove, function (err, value) {
    if (err) return cb(err)
    console.log(value.toString())
    cb()
  })
})

Read stream on Geth DB

var level = require('level')
var Trie = require('./secure')

var stateRoot = "0xd7f8974fb5ac78d9ac099b9ad5018bedc2ce0a72dad1827a1709da30580f0544" // Block #222

var db = level('YOUR_PATH_TO_THE_GETH_CHAIN_DB')
var trie = new Trie(db, stateRoot)

trie.createReadStream()
  .on('data', function (data) {
    console.log(data)
  })
  .on('end', function() {
    console.log('End.')
  })

API

./docs/

TESTING

npm test

REFERENCES

• "Exploring Ethereum's state trie with Node.js" blog post
• "Merkling in Ethereum" blog post
• Ethereum Trie Specification Wiki
• "Understanding the ethereum trie" blog post
• "Trie and Patricia Trie Overview" Video Talk on Youtube

LICENSE

MPL-2.0