A Day After Losing My Crypto Wallet Mnemonic Phrase

Understanding Mnemonic Phrases

Before diving into my personal ordeal, let's briefly cover what mnemonic phrases are for those new to cryptocurrency:

• Digital currencies are products of blockchain technology, pioneered by Bitcoin in 2009. Today, there are over 6,000 types.
• Crypto wallets store assets long-term, unlike exchanges (e.g., Binance, Coinbase).
• Mnemonic phrases act as master keys—typically 12-24 words—generating and recovering wallets. Lose them, and you lose access permanently.

The Incident

In 2021, I bought several cryptocurrencies for research purposes, stored them in a wallet, and wrote down the 12-word mnemonic phrase. Recently, I tried restoring the wallet but hit a wall:

"Invalid mnemonic phrase. Please check."

Panic set in. Upon reviewing my handwritten note, I realized I’d only recorded 11 words. One missing word locked me out of potentially thousands in assets.

The Silver Lining

Research revealed that with 11 correct words, brute-forcing the 12th was feasible—though tedious. The math:

• 2048 possible BIP39 words × 12 positions = 24,576 combinations.
• Valid phrases must pass checksum verification, narrowing possibilities significantly.

Recovering the Phrase

Step 1: Validate Possible Combinations

Using the bip39 library, I wrote a script to test valid 12-word phrases incorporating my 11 known words. Results:

• 1,401 valid combinations (down from 24,576).

const bip39 = require('bip39');
const knownWords = ['success', 'hamster', 'scan', ...]; // 11 words
const wordlist = bip39.wordlists.english;
let validPhrases = [];

function findMissingWord(position) {
  wordlist.forEach(word => {
    const testPhrase = [...knownWords];
    testPhrase.splice(position, 0, word);
    if (bip39.validateMnemonic(testPhrase.join(' '))) {
      validPhrases.push(testPhrase.join(' '));
    }
  });
}

Step 2: Match Against My Wallet Address

Manually testing 1,401 phrases was impractical. Instead, I:

1. Retrieved my wallet address (0x67D...D84F) from old emails.
2. Automated address generation for each valid phrase using ethereumjs-wallet:

async function getAddress(mnemonic) {
  const seed = await bip39.mnemonicToSeed(mnemonic);
  const hdk = hdkey.fromMasterSeed(seed);
  const wallet = hdk.derivePath("m/44'/60'/0'/0/0").getWallet();
  return `0x${wallet.getAddress().toString('hex')}`;
}

Success! The script pinpointed the correct phrase by matching the generated address to mine.

Key Takeaways

1. Treat mnemonics like life savings: Store offline, verify backups, and never digitize them.
2. Partial loss is recoverable: With 11/12 words, brute-forcing is viable—but missing more words makes it near-impossible.
3. Decentralization cuts both ways: No customer support can recover lost phrases. You’re your own bank.

👉 Learn how to secure your crypto assets

FAQs

Q: Can I recover a wallet if I lose all 12 words?
A: No. Without the phrase or private key, funds are irretrievable.

Q: Are hardware wallets safer?
A: Yes. They store keys offline, reducing exposure to hacks—but you still must backup the mnemonic.

Q: How do checksums help in recovery?
A: They invalidate randomly guessed phrases, narrowing valid combinations during brute-force attempts.

Disclaimer: Always test recovery phrases with empty wallets first. This story highlights a rare recovery scenario—don’t rely on luck.