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merkletreejs-solidity

(★ 128)

Construct merkle trees with MerkleTree.js and verify merkle proofs in Solidity.

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Download Latest Version (.zip)

- MerkleProof.sol
- Migrations.sol
- 1_initial_migration.js
- 2_deploy_contracts.js
- merkleproof.js
.gitignore
.node-version
LICENSE
Makefile
package-lock.json
package.json
README.md
truffle-config.js
truffle.js

# Installation Guide

1. Get the code

git clone https://github.com/miguelmota/merkletreejs-solidity

Downloads the entire project code from GitHub to your computer.

cd merkletreejs-solidity

Moves into the project folder you just downloaded.

2. Node.js

Easy Recommended

Prerequisites

Git Needed to download the project code from GitHub.
Node.js Node.js must be installed to use npm. The LTS version is recommended.

npm install

Downloads and installs the libraries listed in package.json.

npm start

Starts the development/run server.

✅ After running the command, open the address shown in the terminal (usually something like http://localhost:3000) in your browser.

3. Make

Medium

Prerequisites

Git Needed to download the project code from GitHub.
Make Usually pre-installed on Linux/macOS. On Windows, install separately (e.g. via MSYS2 or WSL).

make test

Compiles the code based on the generated build configuration to produce an executable.

✅ If it finishes without errors, it worked. Try running the generated executable directly.

Pulled directly from this repo's README.

// repository documentation

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# MerkleTree.js Solidity example

> Construct merkle trees with [MerkleTree.js](https://github.com/miguelmota/merkletreejs) and verify merkle proofs in [Solidity](https://github.com/ethereum/solidity).

## Example

[`contracts/MerkleProof.sol`](./contracts/MerkleProof.sol)

```solidity
pragma solidity ^0.5.2;

contract MerkleProof {
  function verify(
    bytes32 root,
    bytes32 leaf,
    bytes32[] memory proof
  )
    public
    pure
    returns (bool)
  {
    bytes32 computedHash = leaf;

for (uint256 i = 0; i < proof.length; i++) {
      bytes32 proofElement = proof[i];

if (computedHash <= proofElement) {
        // Hash(current computed hash + current element of the proof)
        computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
      } else {
        // Hash(current element of the proof + current computed hash)
        computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
      }
    }

// Check if the computed hash (root) is equal to the provided root
    return computedHash == root;
  }
}
```

[`test/merkleproof.js`](./test/merkleproof.js)

```js
const MerkleProof = artifacts.require('MerkleProof')
const MerkleTree = require('merkletreejs')
const keccak256 = require('keccak256')

const contract = await MerkleProof.new()

const leaves = ['a', 'b', 'c', 'd'].map(v => keccak256(v))
const tree = new MerkleTree(leaves, keccak256, { sort: true })
const root = tree.getHexRoot()
const leaf = keccak256('a')
const proof = tree.getHexProof(leaf)
console.log(await contract.verify.call(root, leaf, proof)) // true

const badLeaves = ['a', 'b', 'x', 'd'].map(v => keccak256(v))
const badTree = new MerkleTree(badLeaves, keccak256, { sort: true })
const badProof = badTree.getHexProof(leaf)
console.log(await contract.verify.call(root, leaf, badProof)) // false
```

## Test

```bash
make test
```

## License

MIT