How can I access data (such as WiFi keys) in an encrypted Titanium backup?

How can I decrypt an encrypted "Titanium Backup" backup **using standard (Linux) tools**? ### Example: Wi-Fi serves as a practical example, many other uses may apply to the solution I'm looking for. If I quickly want to access backed-up Wi-Fi 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 on 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: https://www.titaniumtrack.com/kb/titanium-backup-kb/titanium-backup-cryptography.html