(Laptop) Data Theft Prevention | Joachim De Zutter
Windows and Linux systems can be secured to protect the privacy and intellectual property from unauthorized parties. The process is explained on the following links:

Installing Ubuntu Linux 8.04 With Full Disk Encryption (dm-crypt / Alternate Install CD)

How to Create an Encrypted Container File With BitLocker on Windows

Wikipedia: BitLocker

Sysinternals SDelete (Secure Delete): freeware command line windows utility to securely delete files and overwrite free disk space.

GnuPG GNU Privacy Guard (OpenPGP implementation)

http://www.gnupg.org/

After booting from a Linux Ubuntu live CD with the boot parameter ramdisk_size=65536 it is also possible to use GnuPG to RSA encrypt (up to 4096 bit keys) a 64MB ramdisk to and from a file:

Make a password protected RSA keypair:
gpg --gen-key
Choose 5, RSA (sign) & f.e. 4096 bits
Edit the key to add a subkey which can be used for RSA encryption:
gpg --edit-key followed by the key ID of the keypair obtained in the previous step
addkey
Choose 6, RSA (encrypt only) & f.e. 4096 bits

Copy the created ~/.gnupg/*.gpg keypairs to a storage medium so that they can later be used again.

Script for loading the ramdisk from a persistent storage medium:
grep '/dev/ram0' /proc/mounts
if [ $? -ne 0 ] ; then
  mke2fs /dev/ram0
  cat ./ramdisk.gpg | gpg --decrypt | bzip2 -d --stdout >/dev/ram0
  mkdir -p /tmp/ramdisk
  mount /dev/ram0 /tmp/ramdisk
fi
After this, ls -al /tmp/ramdisk displays the ramdisk contents and it can be used.

Script for encrypting the ramdisk onto a persistent storage medium:
grep '/dev/ram0' /proc/mounts
if [ $? -eq 0 ] ; then
  umount /dev/ram0
  cat /dev/ram0 | bzip2 -c --stdout | gpg --encrypt >./ramdisk.gpg
  shred -vz /dev/ram0
fi
Windows GnuPG binaries: http://gpg4win.org/download.html

Electronic Frontier Foundation (EFF): Surveillance Self Defense:

https://ssd.eff.org/