TrueCrypt is one of the best solution for file encryption in general and is open source. Recently the team in charge of TrueCrypt released TrueCrypt for Linux with a GUI previously the only way to use it was via CLI. If you use TrueCrypt for Windows you might notice that some of the features are missing in Linux, any way now you have the ability of mounting a TrueCrypt volume between platforms with out any major limitations. I use Kubuntu and Windows XP most of the time, this release is welcome.
At the time of the tutorial version 5.1a was available
Open the terminal and use the commands below
tar zxvf truecrypt-5.1a-ubuntu-x86.tar.gz
sudo dpkg -i truecrypt_5.1a-0_i386.deb
TrueCrypt is now installed to use it open the terminal or ALT-F2 and type “truecrypt”. The previous installation should work with most distributions, if you have any question just ask me.