How do I create a keypair using a custom derivation path with Javascript?

Question

I have a seed phrase that I used to generate an address with and sent tokens to it. I entered the seed phrase into Solflare wallet but it can't find the address with tokens on it.

How do I create a keypair using a custom derivation path so I can perform transactions with it?

Answer 1

Using Javascript

This can be done with the ed25519-hd-key and tweetnacl libraries.

Make sure you start the path with m/44'/501', as this is required for Solana addresses.

Setup (run this in your terminal):

npm init -y && npm i @solana/web3.js bip39 tweetnacl buffer ed25519-hd-key

Create a file with this code and run it with node <FILENAME.js>:

import { Keypair } from '@solana/web3.js';
import * as bip39 from 'bip39';
import nacl from 'tweetnacl';
import { Buffer } from 'buffer';
import * as ed25519 from 'ed25519-hd-key';

// Replace with your mnemonic
const mnemonic = 'cabbage together debris chalk hammer novel wire tunnel rubber labor retire prefer';

// Convert the mnemonic to a seed
const seed = bip39.mnemonicToSeedSync(mnemonic).slice(0, 32);

// Define the derivation path
const path = `m/44'/501'/0'/0'`; // Replace with your custom path

// Derive a seed from the given path
const derivedSeed = ed25519.derivePath(path, Buffer.from(seed, 'hex')).key;

// Generate a keypair from the derived seed using tweetnacl (NaCl = Networking and Cryptography library)
const derivedUint8Keypair = nacl.sign.keyPair.fromSeed(derivedSeed);

// This is a Uint8Array, not a Solana web3.js Keypair object, so you will need to convert it
const customPathKeypair = Keypair.fromSecretKey(
  Uint8Array.from(derivedUint8Keypair.secretKey)
);

console.log('Custom Path Keypair address:', customPathKeypair.publicKey.toBase58());

Using wallets

The Backpack wallet supports arbitrary derivation paths, so you can just import your seed phrase into it and set the path.

https://backpack.app/downloads

Answer 2

You can do this:

import { Keypair } from "@solana/web3.js";
import * as bip39 from "bip39";
import { HDKey } from "micro-ed25519-hdkey";

/**
 * Generates a keypair from a mnemonic phrase and allows for modification of the derivation path.
 *
 * @param {string} phrase - The mnemonic phrase.
 * @param {string} [path=m/44'/501'/0'/0'] - The derivation path (default value is `m/44'/501'/0'/0'`).
 * @returns {Keypair} - The keypair generated from the mnemonic phrase and path.
 */
const keyPairFromPhrase = (
  phrase: string,
  path = `m/44'/501'/0'/0'`
): Keypair => {
  // generate seed from mnemonic phrase
  const seed = bip39.mnemonicToSeedSync(phrase, "");

  // derive HD key from seed
  const hdKey = HDKey.fromMasterSeed(seed.toString("hex"));

  // derive keypair from HD key and specified path
  const keypair = Keypair.fromSeed(hdKey.derive(path).privateKey);
  return keypair;
};

You will generate (by default) the same keys than Phantom (https://help.phantom.app/hc/en-us/articles/12988493966227-What-derivation-paths-does-Phantom-wallet-support). I leave another reference for seeing how derivation paths are determined there and in Ledger (it could be useful too). I hope this helps!