When setting up the 3-key vault (2-of-3 multisig) in the Casa app, the default key selection is:
- One mobile key (held on your phone)
- One hardware key (a Trezor, Ledger, Coldcard, etc.)
- One Casa Recovery Key (held by Casa for emergencies in case something happens to one of the other keys)
This is the configuration we believe will work best for most people. It’s easy to understand, the mobile key is encrypted and backed up for redundancy, and you can store the hardware key in a different location than your home to add a layer of security.
People using the bitcoin (BTC) vault in the Casa app have the ability to switch to a more advanced configuration if you would like, which replaces the mobile key with a second hardware key. This means no private key is held on your phone. Instead, you will use two separate hardware devices.
If you choose to do that, your keys would change to:
- Two hardware keys, preferably by different manufacturers (Ledger, Trezor, Coldcard, etc.)
- One Casa Recovery Key (held by Casa for emergencies in case something happens to one of the other keys)
If you aren't sure which setup to use, here are some benefits of each:
| Mobile key and hardware key | Two hardware keys |
| Recommended for beginners. | Optional for advanced users. |
| Mobile key is securely encrypted and backed up to iCloud or Google Drive so you don't have to worry about losing it. | Less reliance on Casa, since the Casa app is not helping you manage a private key. |
| More convenient to sign transactions. You can add one signature from your phone. | Allows you to distribute the keys geographically, so you never have a private key on your person. |
| One private key is stored in your phone's secure enclave. | Two private keys are stored offline on your hardware devices. |
If you have already set up your mobile key and would like to switch your setup to use a second hardware key instead, you can check out our article on replacing a hardware device in the Casa app.
Note that the option to have two hardware devices in a Casa ether (ETH) vault is not yet available.
