Replacing your mobile key with a second hardware key

You can optionally replace your Casa vault's mobile key with a hardware key.

Note: This ability to "opt out" of the mobile key is available for 3-key bitcoin (BTC) vaults only.

Your 3-key vault in the Casa app uses 2-of-3 multisig technology, and has three keys by default:

• 1 x mobile key (held on your phone)
• 1 x hardware key (a Trezor, Ledger, Coldcard, etc.)
• 1 x Casa Recovery Key (held by Casa for emergencies in case you lose one of the other keys)

While most Casa members have the above key setup, we allow members the option to replace the mobile key with a second hardware key so that the three keys become:

• 2 x hardware keys (Ledger, Trezor, Coldcard, etc.)
• 1 x Casa Recovery Key (held by Casa for emergencies in case you lose one of the other keys)

For security purposes, if you are using two hardware keys, we recommend they be from different manufacturers. Otherwise a dysfunctional or malicious firmware update from one manufacturer could affect the security of enough of your keys to affect the security of your funds.

The option to replace the mobile key is built into the Casa app. While we recommend using the default setup (with the mobile key), we do like to give members as much control over their setup as possible.

Using the non-standard setup with two hardware keys is recommended for advanced users only! 

Not sure if you want to use two hardware devices in your setup? Check out this article on choosing your 3-key vault setup, which walks through the advantages and disadvantages of each option.

If you do want to change your setup from a mobile key to a second hardware key, follow the instructions below:

Replacing your mobile key

In order to replace your mobile key with a second hardware key, you must have a second hardware device available and ready to use. We recommend you use your hardware devices exclusively with Casa, so you should use a hardware device that's not currently being used to store anything else.

Please note: For the two hardware key setup, we highly recommend keeping a copy of the seed phrases for both of the hardware devices. Just as we recommend separating the two keys geographically, we recommend storing the seed phrase backups in different places as well.

If you have funds in your 3-key vault, replacing your existing mobile key with a second hardware key involves an on-chain transaction to a new keyset you'll create in the Casa app. 

1. From within the Casa app, tap the key icon for your vault
2. On the "Vault keys" screen, tap the three dots at the top right.
3. Then tap the "Switch Key Setup" button that appears at the bottom.
4. Click "Yes, continue."
5. Tap "Continue, I have my two keys."
6. Follow the instructions to connect your new hardware key.
7. Transfer your funds from the old keyset to your new keyset (we’ll guide you through it in the app).

NOTE: If you're taking advantage of the "Subaccounts" feature in the Casa app and you have an additional subaccount vault, then you will also need to send funds to the new keyset from your subaccount vault, in addition to your primary vault. 

You're all set! Don't forget to complete a health check for your hardware devices to ensure they are both working properly.