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https://github.com/merkletreejs/merkletreejs

🌱 Construct Merkle Trees and verify proofs in JavaScript.
https://github.com/merkletreejs/merkletreejs

bitcoin blockchain ethereum javascript merkle merkle-mountain-range merkle-multiproof merkle-proof merkle-root merkle-tree merkle-tree-diagram merkletreejs mmr multiproof nodejs protocol smart-contracts soli solidity verify-proofs

Last synced: about 14 hours ago
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🌱 Construct Merkle Trees and verify proofs in JavaScript.

Host: GitHub
URL: https://github.com/merkletreejs/merkletreejs
Owner: merkletreejs
License: mit
Created: 2017-07-22T07:25:26.000Z (over 7 years ago)
Default Branch: master
Last Pushed: 2024-12-27T00:16:57.000Z (about 1 month ago)
Last Synced: 2025-01-30T19:06:42.208Z (8 days ago)
Topics: bitcoin, blockchain, ethereum, javascript, merkle, merkle-mountain-range, merkle-multiproof, merkle-proof, merkle-root, merkle-tree, merkle-tree-diagram, merkletreejs, mmr, multiproof, nodejs, protocol, smart-contracts, soli, solidity, verify-proofs
Language: TypeScript
Homepage: https://merkletree.js.org
Size: 1.07 MB
Stars: 1,187
Watchers: 20
Forks: 216
Open Issues: 24
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- Funding: .github/FUNDING.yml
- License: LICENSE

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# MerkleTree.js

> Construct [Merkle Trees](https://en.wikipedia.org/wiki/Merkle_tree) and verify proofs in JavaScript.

[![License](http://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/miguelmota/merkletreejs/master/LICENSE)

[![Documentation](https://img.shields.io/badge/documentation-latest-blue.svg)](https://github.com/miguelmota/merkletreejs/tree/master/docs)

[![Build Status](https://travis-ci.org/miguelmota/merkletreejs.svg?branch=master)](https://travis-ci.org/miguelmota/merkletreejs)

[![dependencies Status](https://david-dm.org/miguelmota/merkletreejs/status.svg)](https://david-dm.org/miguelmota/merkletreejs)

[![NPM version](https://badge.fury.io/js/merkletreejs.svg)](http://badge.fury.io/js/merkletreejs)

[![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](#contributing)

## Contents

- [Install](#install)

- [Example](#example)

- [Getting started](#Getting-started)

- [Diagrams](#diagrams)

- [Documentation](#documentation)

- [Test](#test)

- [FAQ](#faq)

- [Notes](#notes)

- [Resources](#resources)

- [Contributing](#contributing)

- [License](#license)

## Install

From [NPM](https://www.npmjs.com/package/merkletreejs):

```bash

npm install merkletreejs

```

Import as ES6 module

```js

import { MerkleTree } from 'merkletreejs'

```

Import as CommonJs

```js

const { MerkleTree } = require('merkletreejs')

```

### CDN

Available on [jsDelivr](https://www.jsdelivr.com/) CDN:

```html

```

The exported classes will be available on `window` object, e.g. `window.MerkleTree`

## Example

[https://lab.miguelmota.com/merkletreejs](https://lab.miguelmota.com/merkletreejs)

## Getting started

Construct tree, generate proof, and verify proof:

```js

const { MerkleTree } = require('merkletreejs')

const SHA256 = require('crypto-js/sha256')

const leaves = ['a', 'b', 'c'].map(x => SHA256(x))

const tree = new MerkleTree(leaves, SHA256)

const root = tree.getRoot().toString('hex')

const leaf = SHA256('a')

const proof = tree.getProof(leaf)

console.log(tree.verify(proof, leaf, root)) // true

const badLeaves = ['a', 'x', 'c'].map(x => SHA256(x))

const badTree = new MerkleTree(badLeaves, SHA256)

const badLeaf = SHA256('x')

const badProof = badTree.getProof(badLeaf)

console.log(badTree.verify(badProof, badLeaf, root)) // false

```

Print tree to console:

```js

console.log(tree.toString())

```

Output:

```bash

└─ 7075152d03a5cd92104887b476862778ec0c87be5c2fa1c0a90f87c49fad6eff

   ├─ e5a01fee14e0ed5c48714f22180f25ad8365b53f9779f79dc4a3d7e93963f94a

   │  ├─ ca978112ca1bbdcafac231b39a23dc4da786eff8147c4e72b9807785afee48bb

   │  └─ 3e23e8160039594a33894f6564e1b1348bbd7a0088d42c4acb73eeaed59c009d

   └─ 2e7d2c03a9507ae265ecf5b5356885a53393a2029d241394997265a1a25aefc6

      └─ 2e7d2c03a9507ae265ecf5b5356885a53393a2029d241394997265a1a25aefc6

```

## Diagrams

▾ Visualization of Merkle Tree



▾ Visualization of Merkle Tree Proof



▾ Visualization of Invalid Merkle Tree Proofs



▾ Visualization of Bitcoin Merkle Tree



## Documentation

See [documentation](docs/classes/_src_merkletree_.merkletree.md) (under [docs/](docs/))

## Test

```bash

npm test

```

## FAQ

- Q: How do you verify merkle proofs in Solidity?

  - A: Check out the example repo [merkletreejs-solidity](https://github.com/miguelmota/merkletreejs-solidity) on how to generate merkle proofs with this library and verify them in Solidity.

- Q: How do you verify merkle [multiproofs](https://github.com/ethereum/eth2.0-specs/blob/dev/ssz/merkle-proofs.md#merkle-multiproofs) in Solidity?

  - A: Check out the example repo [merkletreejs-multiproof-solidity](https://github.com/miguelmota/merkletreejs-multiproof-solidity) on how to generate merkle multiproofs with this library and verify them in Solidity.

- Q: Is there an NFT whitelist example in Solidity?

  - A: Check out the example repo [merkletreejs-nft-whitelist](https://github.com/miguelmota/merkletreejs-nft-whitelist) on how to generate merkle root of whitelisted accounts and merkle proofs with this library and verify them in Solidity.

- Q: What other types of merkle trees are supported?

  - Besides standard `MerkleTree`, there's also `MerkleMountainRange`, `MerkleSumTree`, `IncrementalMerkleTree`, and `MerkleRadixTree` implementation classes available. For Merkle Patricia Tree, see [`@ethereumjs/trie`](https://www.npmjs.com/package/@ethereumjs/trie).

- Q: How do I hash a JSON object?

- See [`https://www.npmjs.com/package/json-stable-stringify`](https://www.npmjs.com/package/json-stable-stringify) for deterministic stringifying of JSON objects.

- Q: Is there a CLI version of this library?

  - Yes, see [merkletreejs-cli](https://github.com/miguelmota/merkletreejs-cli).

- Q: Is there a way to visualize the merkle trees in the browser?

  - Yes, see [example ui](https://lab.miguelmota.com/merkletreejs) and [merkletree-viz](https://github.com/miguelmota/merkletree-viz).

## Notes

As is, this implementation is vulnerable to a [second pre-image attack](https://en.wikipedia.org/wiki/Merkle_tree#Second_preimage_attack). Use a difference hashing function for leaves and nodes, so that `H(x) != H'(x)`.

Also, as is, this implementation is vulnerable to a forgery attack for an unbalanced tree, where the last leaf node can be duplicated to create an artificial balanced tree, resulting in the same Merkle root hash. Do not accept unbalanced tree to prevent this. More info [here](https://bitcointalk.org/?topic=102395).

Please use the library [`@openzeppelin/merkle-tree`](https://github.com/OpenZeppelin/merkle-tree) if you're integrating with OpenZeppelin contracts or using multiproofs. There are known issues with the current multiproof implementation as pointed out in [issues](https://github.com/merkletreejs/merkletreejs/issues/63).

### Disclaimer

This library was created for my own purposes and is provided as-is. Use at your own risk.

## Resources

- [Bitcoin mining the hard way: the algorithms, protocols, and bytes](http://www.righto.com/2014/02/bitcoin-mining-hard-way-algorithms.html)

- [Bitcoin Talk - Merkle Trees](https://bitcointalk.org/index.php?topic=403231.msg9054025#msg9054025)

- [How Log Proofs Work](https://www.certificate-transparency.org/log-proofs-work)

- [Raiden Merkle Tree Implementation](https://github.com/raiden-network/raiden/blob/f9cf12571891cdf54feb4667cd2fffcb3d5daa89/raiden/mtree.py)

- [Why aren't Solidity sha3 hashes not matching what other sha3 libraries produce?](https://ethereum.stackexchange.com/questions/559/why-arent-solidity-sha3-hashes-not-matching-what-other-sha3-libraries-produce)

- [What is the purpose of using different hash functions for the leaves and internals of a hash tree?](https://crypto.stackexchange.com/questions/2106/what-is-the-purpose-of-using-different-hash-functions-for-the-leaves-and-interna)

- [Why is the full Merkle path needed to verify a transaction?](https://bitcoin.stackexchange.com/questions/50674/why-is-the-full-merkle-path-needed-to-verify-a-transaction)

- [Where is Double hashing performed in Bitcoin?](https://bitcoin.stackexchange.com/questions/8443/where-is-double-hashing-performed-in-bitcoin)

- [Compact Merkle Multiproofs](https://arxiv.org/pdf/2002.07648.pdf)

- [Eth 2.0 specs - Merkle Multiproofs](https://github.com/ethereum/eth2.0-specs/blob/dev/ssz/merkle-proofs.md#merkle-multiproofs)

- [What is complete binary tree?](https://xlinux.nist.gov/dads/HTML/completeBinaryTree.html)

- [What is perfect binary tree?](https://xlinux.nist.gov/dads/HTML/perfectBinaryTree.html)

## Contributing

Pull requests are welcome!

For contributions please create a new branch and submit a pull request for review.

_Many thanks to all the [contributors](https://github.com/miguelmota/merkletreejs/graphs/contributors) that made this library better._

## License

Released under the [MIT](./LICENSE) license.

© [Miguel Mota](https://github.com/miguelmota)