Linux backup software .. that meets unique requirements

[David Rosenstrauch]

Trying to find linux backup software that meets what apparently is a 
unique set of requirements.  I've checked out all the major backup apps 
(backuppc, duplicity, bacula, drop.io, etc.) but none of them seem to 
meet all of my requirements.  Anyone here know of one that does?  Here's 
what I'm looking for:

1) Backs up efficiently.  e.g., uses rsync algorithm or similar so as to 
not repeatedly backup/store files that haven't changed.

2) Transmission of backups is encrypted.

3) Storage of backups is encrypted.

4) Can back up to offsite/remote file system.

5) Can back up to any old plain vanilla sftp/rsync-accessible remote 
file system.  (Reason behind this requirement is that I already have 
access to a large amount of (non-encrypted) space for backups, and don't 
want to pay extra for another service.)

6) Does not require that you periodically take the network i/o storage 
hit of making a new full backup.  (This is not an option, as what the 
data I want to back up is getting large, and I only want to do it once.)

For some reason it's impossible to find something that fits all of the 
above.

* backuppc and rsyn don't satisfy #3.

* duplicity doesn't satisfy #6.

* drop.io and bacula don't satisfy #5.

etc.


Anyone have any suggestions here?  I'm actually on the verge of writing 
my own backup software to do this, but I'd *really* like to avoid that 
unless there's no other choice.


Thanks,

DR