merklevalidator
v3.0.0
Published
Construct Merkle Trees and verify proofs
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MerkleTree.js
Construct Merkle Trees and verify proofs in JavaScript.
Contents
Install
From NPM:
npm install merkleValidator
Import as ES6 module
import { MerkleTree } from 'merkleValidator'
Import as CommonJs
const { MerkleTree } = require('merkleValidator')
CDN
Available on jsDelivr CDN:
<script src="https://cdn.jsdelivr.net/npm/merkletreejs@latest/merkletree.js"></script>
The exported classes will be available on window
object, e.g. window.MerkleTree
Example
https://lab.miguelmota.com/merkletreejs
Getting started
Construct tree, generate proof, and verify proof:
const { MerkleTree } = require('merkleValidator')
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:
console.log(tree.toString())
Output:
└─ 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 (under docs/)
Test
npm test
FAQ
Q: How do you verify merkle proofs in Solidity?
- A: Check out the example repo merkletreejs-solidity on how to generate merkle proofs with this library and verify them in Solidity.
Q: How do you verify merkle multiproofs in Solidity?
- A: Check out the example repo 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 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 alsoMerkleMountainRange
,MerkleSumTree
, andIncrementalMerkleTree
implemenation classes available.
- Besides standard
Q: Is there a CLI version of this library?
- Yes, see merkletreejs-cli.
Q: Is there a way to visualize the merkle trees in the browser?
- Yes, see merkletree-viz.
Notes
As is, this implemenation is vulnerable to a second pre-image 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.
Please use the library @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.
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
Why aren't 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?
License
Released under the MIT license.