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 multisig setup for Gold members, and is also used as a key in the 3 of 5 multisig setup 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 backed up?"
The Mobile Key is stored within the secure enclave of your phone, 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 Apple. If you're using an Android phone, the single key is backed up to Google.
In order for the Mobile Key to be automatically backed up, you need to be signed into Apple (if you're using an iPhone) or Google (if you're using an Android phone) 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?"
If you get a new phone, and want to restore your Mobile Key, simply log into the 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 the Casa App on a new phone. See:
"How do I set it up?"
You set up your Mobile Key, simply tap the Mobile Key icon in the 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 the 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.