protocol:
{
  "driver": "file",
  "filename": "/var/lib/libvirt/images/i.img",
  "size": 4294967296
}

format:
{
  "key-secret": "0123456789ABCDEF0123456789ABCDE-encalias",
  "driver": "luks",
  "file": "0123456789ABCDEF0123456789ABCDE",
  "size": 8589934590
}