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

Here is an article on extracting “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 will explore how to obtain xpriv and xpub keys from a generated Bitcoin public/private key pair using the bitcoinjs-lib library.

Prerequisites

Before continuing, make sure you have the following installed:

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

• 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 the private key to PEM format for easier processing
const privateKeyPem = bitcoin.privateKeyToPem(privateKey);
console.log(Private Key (PEM): ${privateKeyPem});
// Extract the 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” command.

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

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

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

Tips and Variations

• If you are 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 unnecessary conversions.

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

• If you are working with large files or need more advanced cryptographic functionality, consider using other Bitcoin libraries such as bitcoinjs-core or ethers.js.

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

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