The Mobile Key is one of the keys in your multisig setup that can be used to sign and send transactions.
The Mobile Key is standard in the 2-of-3 Basic Multisig setup for Gold members, and is also used as a key in the 3-of-5 multisig Key Shield for Platinum and Diamond members.
We do allow Gold users the option to replace the Mobile Key with a second hardware device key if desired (for advanced users only!)
How is it generated?
The Mobile Key is generated locally on your personal mobile device in its Secure Enclave. The key never touches Casa servers. This is why even if someone obtained access to your Casa account credentials, they would not be able to access your Mobile Key on their own device unless they also obtained access to the key's cloud backup.
How is it backed up?
The Mobile Key is encrypted and backed up to your phone's default cloud service. No need to write down a seed phrase!
If you're using an iPhone, the Mobile Key is backed up to iCloud. If you're using an Android phone, the single key is backed up to Google Drive.
In order for the Mobile Key to be backed up automatically, you need to be signed into your Apple (if you're using an iPhone) or Google (if you're using an Android phone) account in the system settings of your phone.
At no point does Casa ever have access to your Mobile Key, and since the backup is encrypted, your cloud storage provider can't access your key either.
What if I get a new phone?
Because the key only exists on your specific phone and backed up to your cloud drive, if you get a new phone, you need to make sure you get a copy of the key on the new phone. To do this, simply log into Casa App on your new phone, and restore the key from backup. As long as you're signed into the same Apple or Google account on the new phone as when you first set up the key, you're good to go!
If you ever lose your phone or get a new phone, we have guides on how to restore Casa App on a new phone. See:
If you're transitioning between phone operating systems, make sure you get the key set up on the new phone before you get rid of the old one! See the instructions in our article Switching between iPhone and Android for more details.
How do I set it up?
To set up your Mobile Key, simply tap the Mobile Key icon in Casa App and choose "Setup Mobile Key." Follow the instructions to set up and back up your Mobile Key. Here's what that looks like:
Once your Mobile Key is set up, it can be immediately used for signing transactions in Casa App. Periodically (at least 2 times per year, or once every 6 months), we recommend doing a quick Health Check on the Mobile Key, to make sure it's on your device and backed up in the cloud.