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 *W*46.*gz  
> com.keramidas.virtual.WIFI_AP_LIST-20120622-105046.tar.gz  
> root@android:/sdcard/TitaniumBackup # gunzip -c *W*46.*gz | grep -C1 MyAccessPoint      
> network={  
>>	ssid="MyAccessPoint"  
>>	psk="supersecrecretpassphrase"  

*Some* details on the company's site: http://www.titaniumtrack.com/kb/titanium-backup-kb/titanium-backup-cryptography.html