Ethereum: How to get xpriv and xpub from keyPair with bitcoinjs-lib
Here is an article explaining 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 will explore how to obtain the “xpriv” and “xpub” keys from a Bitcoin public/private key pair generated using the “bitcoinjs-lib” library.
Prerequisites
Before proceeding, make sure 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)
Sample Code
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 manipulation
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(Public Key X: ${xpub});
console.log(Private Key X: ${xpriv});
Explanation
In this example:
- We create a new
ECPairinstance usingbitcoinjs-lib.
- Generate a random private key using
makeRandom(). This function returns anECPairobject.
- We convert the generated private key to PEM format for easier manipulation by calling
privateKeyToPem()on our private key object.
- We extract the X-Public and X-Private keys from the private key using
xpubandxprivrespectively 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 redundant conversions.
- You can also use
ECPair.fromPrivateKey()instead ofmakeRandom()if you already have a trusted private key.
- If you are dealing with large files or need more advanced cryptographic operations, consider using other Bitcoin libraries such as
bitcoinjs-coreorethers.js.
By following these steps and understanding the process, you should be able to extract the “xpriv” and “xpub” keys from the generated key pair. Happy coding!