Crypted disk image
From Alessandro's Wiki
http://www.techrepublic.com/blog/opensource/create-encrypted-loopback-filesystems-on-linux/67
dd if=/dev/urandom of=crypted_image.img bs=1M count=50
losetup -e aes /dev/loop0 crypted_image.img Password:
mkfs -t ext2 /dev/loop0
mount -o loop,encryption=aes crypted_image.img /media/disk
