This new KMS is based on the (default) SecretsKMS, but instead of using
the passphrase for all volumes, the passphrase is used to
encrypt/decrypt a Data-Encryption-Key that is stored in the metadata of
the volume.
CC: Patrick Uiterwijk <puiterwijk@redhat.com> - for encryption guidance
Signed-off-by: Niels de Vos <ndevos@redhat.com>
