[rdiff-backup-users] Data Privacy from system administrator with rdiff-backup

[Dominic]

Is it possible with rdiff-backup to create backups on a (linux) backup 
server which cannot then be accessed by the system administrator? I 
think that Duplicity was created to provide this privacy, but in other 
respects rdiff-backup seems a much more polished solution and I wondered 
if this problem can be overcome while sticking with rdiff-backup.

For instance, no sort of third-party rdiff-backup-based backup solution 
is really satisfactory if the third party administrator can just read 
any customer's backed-up private files.

Dominic