How can I decrypt an encrypted "Titanium Backup" backup using standard (linux) tools?

Example (wifi's just an example, there are other uses too):

If I quickly want to access backuped wifi credentials from my linux box I know a fast way. With encrypted backups I'm currently out of luck.

That's my quick&dirty way how to do it without encryption so far:

me@local:~$ adb shell
root@android:/ # cd /sdcard/TitaniumBackup/
root@android:/sdcard/TitaniumBackup # ls W46.*gz
com.keramidas.virtual.WIFI_AP_LIST-20120622-105046.tar.gz
root@android:/sdcard/TitaniumBackup # gunzip -c W46.*gz | grep -C1 MyAccessPoint
network={

ssid="MyAccessPoint"
psk="supersecrecretpassphrase"