I imagine you're doing backups or long term archive of data
Try either BoxBackup or Duplicity.

Both of these encrypt on the source machine, copy just the changes to the backup server.

If the backup machine gets stolen, no worries - it's all encrypted.

Boxbackup I find awkward to set up and logging is shocking. All uses SSL certs. It does, however, keep an unspecified amount of 'old data', which it starts deleting when it runs out of space.

Duplicity works by public key encryption of diff'd tar archives, copied to the backup server. Very easy to set up and manage.

Take it one step further and sign the archives, then noone can add to them without breaking the seal.
(MrOli is ugly, but in the morning you will be sober, Wed 4 Feb 2009, 13:16, Reply)