merkletreejs
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    MerkleTree.js

    Construct Merkle Trees and verify proofs in JavaScript.

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    Contents

    Install

    From NPM:

    npm install merkletreejs

    CDN

    Available on jsDelivr CDN:

    <script src="https://cdn.jsdelivr.net/npm/merkletreejs@latest/merkletree.js"></script>

    Example

    https://lab.miguelmota.com/merkletreejs

    Getting started

    Construct tree, generate proof, and verify proof:

    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 = tree.getProof(badLeaf)
    console.log(tree.verify(badProof, leaf, root)) // false

    Print tree to console:

    console.log(tree.toString())

    Output:

    └─ 7075152d03a5cd92104887b476862778ec0c87be5c2fa1c0a90f87c49fad6eff
       ├─ e5a01fee14e0ed5c48714f22180f25ad8365b53f9779f79dc4a3d7e93963f94a
       │  ├─ ca978112ca1bbdcafac231b39a23dc4da786eff8147c4e72b9807785afee48bb
       │  └─ 3e23e8160039594a33894f6564e1b1348bbd7a0088d42c4acb73eeaed59c009d
       └─ 2e7d2c03a9507ae265ecf5b5356885a53393a2029d241394997265a1a25aefc6
          └─ 2e7d2c03a9507ae265ecf5b5356885a53393a2029d241394997265a1a25aefc6

    Diagrams

    ▾ Visualization of Merkle Tree

    Merkle Tree

    ▾ Visualization of Merkle Tree Proof

    Merkle Tree Proof

    ▾ Visualization of Invalid Merkle Tree Proofs

    Merkle Tree Proof

    ▾ Visualization of Bitcoin Merkle Tree

    Merkle Tree Proof

    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?

    • 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: Is there a CLI version of this library?

    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.

    Resources

    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 that made this library better.

    Tip Jar

    BTC Tip Jar 3KdMW53vUMLPEC33xhHAUx4EFtvmXQF8Kf

    ETH Tip Jar 0x9ed3D6793a6b74d8c9A998f5C4b50a25947D53aF

    Thank you for tips! 🙏

    License

    Released under the MIT license.

    © Miguel Mota

    Install

    npm i merkletreejs

    DownloadsWeekly Downloads

    59,156

    Version

    0.2.32

    License

    MIT

    Unpacked Size

    267 kB

    Total Files

    12

    Last publish

    Collaborators

    • miguelmota