Arbitrary string to Mnemonic Phrase

arbitrary-string-to-mnemonic.js

/**
 * Copyright 2024 Kieran Goodary <kieran@digitalindustria.com>
 *
 * Permission is hereby granted, free of charge, to any 
 * person obtaining a copy of this software and associated 
 * documentation files (the “Software”), to deal in the 
 * Software without restriction, including without limitation 
 * the rights to use, copy, modify, merge, publish, distribute,
 * sublicense, and/or sell copies of the Software, and to permit 
 * persons to whom the Software is furnished to do so, subject
 * to the following conditions:
 *
 * The above copyright notice and this permission notice shall 
 * be included in all copies or substantial portions of the 
 * Software.
 *
 * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY
 * KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 
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/**
 * ⚠️ BUT WAIT!!! A note about this code snippet:
 *
 * The core principles of this Gist is to take the shortest
 * malleable route to be able to create a Mnemonic phrase
 * via the Ethers library. DO NOT take this code snippet as
 * secure out-of-the-box or tested in any way. It's designed
 * to be worked to your liking / business process with several
 * points where the one-way cryptography can be strengthened.
 *
 * May the force be with you.
 * Kio ❤️
 */
const crypto = require('crypto');
const createKeccakHash = require('keccak')
const ethers = require('ethers');

// This would be the Firebase User ID, but it could indeed be anything
const arbitraryUserId = "somearbstring123";

// Use "Password-Based Key Derivation Function 2" to create a 
// one-way buffer based on the "ID" above.
// Notes: 
// - Salt is set to 123 as an example, should be something bigger
// - Iterations is set to 1 as an example, should be MUCH higher
// - key length set to 1024
// - HMAC digest set to SHA512. SHA512 is considered a bit overkill
const hash = crypto.pbkdf2Sync(arbitraryUserId, "iamasalt", 1, 1024, 'sha512');

// Generate Mnemonic
// Now can create a mnemonic BIP-39
// sequence of words based from the initial hash generated
// Notes:
// - entropyToPhrase requires a 32 byte entropy. Taking the
//.  hash buffer and slicing the first 32 bytes but you could
//   move this 32 byte slide anywhere within the 1024 frame
const mnemonicPhrase = ethers.Mnemonic.entropyToPhrase(hash.slice(0, 32));
console.log(`Mnemonic Phrase: ${mnemonicPhrase}`);

// Using above mnemonic phrase to generate a HD wallet.
// Defaults to usual derivation path and account 0.
const hdWallet = ethers.Wallet.fromPhrase(mnemonicPhrase);
console.log(`Wallet Private Key: ${hdWallet.privateKey}`);
console.log(`Wallet Address: ${hdWallet.address}`);

// Sign something
const message = "Hello!";
const rawSignature = await hdWallet.signMessage(message);

console.log(`Raw signature: ${rawSignature}`);