iTwin derives its name from the fact that you need two iTwin devices for it to work. When paired with one another, the devices allow users to share files over the Internet using Advanced Encryption Standard (AES) 256 bit encryption. Plug in one to a Mac or PC, assign it files and folders that you want to be accessible, and when the other device is plugged into a second Mac or PC, those folders and files can then be accessed by that machine.[macobserver.com]

Also:

At CES, Singapore-based ST Electronics was showing off a new security device that can be installed in nearly any notebook computer to protect its data from prying eyes—Digisafe DiskCrypt, a hard-disk enclosure that turns any 1.8-inch micro-SATA device into removable and fully encrypted storage. The enclosure, which is the size of a 2.5" drive, can be used as a drop-in replacement for existing drives.[arstechnica.com]