secure backups

[Steven Meyer <meysteven () gmail com>]

I am looking for a backup software that only the Superusers could use
to backup, but only the administrator could restore. That way nobody
could bring data out from the office and I wouldn't need to do
regularly backup on the user computer.
May be the backup should be done with a private and public key.
If anybody has a good idea, it would be very appreciated.
thank you
Steven Meyer