The database encryption key encrypts the database where the device encryption key is stored. It is initialized at the installation of the first instance of the Key Management Server (for On-Premise deployment of SecureCloud). Once you specify a passphrase or accept a generated passphrase for the database encryption key, key back up is possible.

The passphrase is needed to import the backed up data encryption key. You would need to import the data encryption key backup in order to restore a corrupt database encryption key. You would also need to import the data encryption key backup to give any additional Management Servers access to the device encryption key database.