TrueCrypt

Download:

$ wget http://www.truecrypt.org/download/truecrypt-7.1a-linux-x64.tar.gz

Extract the archive:

$ tar -zxvf truecrypt*.gz

Install TrueCrypt:

$ sudo ./truecrypt-7.1a-setup-x86

To uninstall TrueCrypt, do this:

$ sudo truecrypt-uninstall.sh

To run it, just type truecrypt in the terminal:

$ truecrypt