How to migrate a hardware key to a Yubikey

What you'll need

• Your seed phrase for the key you're migrating (12,18, 21, or 24 words, English wordlist).
• Your passphrase, if you originally set one up (optional, most people don't use this).
• A YubiKey with firmware 5.5 or later.
• A computer running Google Chrome. Use your own personal computer. This process can't be completed on a public or shared computer, and it can't be completed from your phone.
• Your phone with the Casa app and access to your email.
• A few uninterrupted minutes, and a private space where no one else can see your screen.

How it works, step by step

1. Start on your phone. Go to the key's detail screen in the Casa app and tap Replace Key. From the Advanced Options screen that opens, select Import seed phrase to YubiKey.

2. A quick safety check. You'll see a reminder that no one should be pressuring you to do this or telling you it's urgent. If anything feels off, contact Casa support instead of continuing. Check the box confirming this is your own choice, then continue.

3. Check your email on your computer. Casa sends an email with the subject "Switch key to a YubiKey." Open it on your personal computer in Chrome, not on your phone. This takes you to a "Let's begin" screen. Keep your phone nearby, you'll need it in the next step.

4. Verify you're on the real Casa site. Enter the 6-digit code shown on your computer into the Casa mobile app. The code refreshes every 2 minutes, so use the most current one. If a site doesn't ask you for this code, or the code doesn't match, stop and contact Casa support.

If you enter the code incorrectly five times, that email link is disabled and you'll need to restart from your phone.

5. Plug in your YubiKey. On your computer, you'll see a few setup tips, including a recommendation to use an incognito browser window.

6. Enter your seed phrase. Select your word count, then enter each word into the grid. Words are hidden by default. Use Show Words if you need to check your entry. Use Clear All if you need to start over. Do this somewhere private.

If you originally set up a passphrase, check "My seed phrase includes a Passphrase" and enter it. Leave it unchecked if you're not sure what this is.

7. Verification. Casa checks your seed phrase against your existing vault key. If it matches, you'll see "Private Key verified." If it doesn't, you'll see a message asking you to check your passphrase, and you can try again.

8. Import. Tap Import Now. Your seed is encrypted and written to your YubiKey.

9. Confirm on your YubiKey. Tap your YubiKey and enter your PIN to finish.

10. You're done. Your key detail screen will update to show your YubiKey with a status of Healthy. Your key's name is preserved, and you'll see the option to create a duplicate YubiKey for backup.

Need help?

If anything during this process feels unclear, unexpected, or urgent in a way that makes you uncomfortable, stop and email help@team.casa.