Ethereum: How to get xpriv and xpub from keyPair with bitcoinjs-lib

Here’s an article on how to extract xpriv and xpub from a Key Pair using the BitcoinJS library:

Extracting X-Public and X-Private Keys from a Key Pair

In this article, we’ll explore how to obtain xpriv and xpub keys from a generated Bitcoin public/private key pair using the bitcoinjs-lib library.

Prerequisites

Before proceeding, ensure you have the following installed:

• bitcoinjs-lib: A Node.js library for interacting with the Bitcoin blockchain.

• A Bitcoin private key pair (generated by bitcoinjs-lib)

Code Example

const bitcoin = require('bitcoinjs-lib');

const keyPair = bitcoin.ECPair.makeRandom({});


// Get the private key

const privateKey = keyPair.private;


// Convert private key to PEM format for easier handling

const privateKeyPem = bitcoin.privateKeyToPem(privateKey);


console.log(Private Key (PEM): ${privateKeyPem});


// Extract X-Public and X-Private keys from the private key

const xpub = keyPair.xpub;

const xpriv = keyPair.xpriv;


console.log(X-Public Key: ${xpub});

console.log(X-Private Key: ${xpriv});

Explanation

In this example:

• We create a new ECPair instance using the bitcoinjs-lib.

• We generate a random private key using makeRandom(). This function returns an ECPair object.

• We convert the generated private key to PEM format for easier handling by calling privateKeyToPem() on our private key object.

• We extract the X-Public and X-Private keys from the private key using xpub and xpriv, respectively, and log them to the console.

Tips and Variations

• If you’re working with a specific key pair or a large number of keys, consider caching the private key before converting it to PEM format to avoid redundant conversions.

• You can also use ECPair.fromPrivateKey() instead of makeRandom() if you already have a trusted private key.

• If you’re dealing with large files or need more advanced cryptographic operations, consider using other Bitcoin libraries like bitcoinjs-core or ethers.js.

By following these steps and understanding the process, you should be able to extract xpriv and xpub keys from your generated Key Pair. Happy coding!

metamask send smart