pmt-builder

PartialMerkleTree builder library.

This library can be used to build a partial merkle tree for a block of transactions. A partial merkle tree is a pruned version of a full merkle tree, containing only the parts needed to prove a given transaction is part of the tree.

Installation

npm install @rsksmart/pmt-builder

Install dependencies

npm install

Usage

To build the tree, simply call the buildPMT function and pass the leaves as a list of strings and a filteredHash in string format, i.e buildPMT(leaves: string[], filteredHash: string)

First parameter {leaves}: An array of transaction hash of all transactions without witness(txid) in a block. Second parameter {filteredHash}: transaction hash (the hash without witness).

The function returns an object with the following fields: totalTX: the size of {leaves} in the array. Hashes: All the hashes that build the partial merkle tree. This includes the leaves level as well as the upper levels of the tree. flags: The number of flags bytes to follow. Hex: The partial merkle tree serialized in hex format.

Sample Snippet

const pmtBuilder = require("@rsksmart/pmt-builder");

const blockTransactions = [
    '8f01832aa125683490e70a9142ccd9c49485b84708180487b5f35dc7795a3afd',
    '6cc629897f3f6c3e873e98af8061f54618fe2be6599853841ca97aeb9614a136',
    '31c8227345ead8477845fda6d8dc68cc1bca9c094523aef60d857d521aca6937',
    'e0714cbc5ed04014e1a1f362612fdb05578a1c8e45257ac6cc0dff0d2e532855',
    '0f9e8932b5bbcad80242077205843e42bcca9d84c58b751535ea07a06e4179e6',
    '5a4d2446ff81be95eacaaac0fcd06856f9625f6f07391a2bf90b1a065be0e0fc'
];

const resultPmt = pmtBuilder.buildPMT(blockTransactions, blockTransactions[0]);
console.log("Result: ", resultPmt);

Tool Usage

This library can be used via a tool(this tool uses mempool.js api to get transactions) that exists in the tool/pmt-builder.js file via the following command:

node tool/pmt-builder.js network blockHash txHash,

For example: node tool/pmt-builder.js testnet 00000000000003d91235b675366fc6c26e0ea4b2f125fd292f164247d4e5b07e ac72bd61c72ac8143e5638998f479bdfc5834fce9576fa2054c7be93313abd66

network: testnet or mainnet blockHash: block hash in hex format txHash: filtered transaction hash in hex format

Test

To run test:

npm test

For any comments or suggestions, feel free to contribute or reach out at our open slack.