[ Thanks to Dmitri
Popov for this link. ]
“Unlike rsync on Linux, the rsync Backup app offers a simple
graphical interface for configuring backup profiles. But before you
set up a backup job on your Android device, you have to generate an
encryption key pair, and the app comes with a built-in feature that
allows you to do that with relative ease. Press the hardware Menu
button and tap on Generate Keys. Once the keys have been generated,
you need to add the public key to the backup machine. On your
Android device, open the /sdcard/dss_key.pub file in a text editor
and copy the contents of the file. Next, use the ConnectBot app to
connect to the backup server, and use the nano
~/.ssh/authorized_keys command to open the authorized_keys file in
the nano text editor. Paste then the public key at the end of the
file, then save and close it. “