TrueCrypt can create a virtual encrypted disk within a file and mount it as a real disk, or an entire hard disk partition or a device, such as USB memory stick, floppy disk, etc.
This software provides two levels of security: a hidden volume (more information may be found here), and a volume cannot be identified (no part of the volume can be distinguished from random data).
It utilizes the following encryption algorithms: AES (256-bit key), Blowfish (448-bit key), CAST5 (128-bit key), Serpent (256-bit key), Triple DES, and Twofish (256-bit key), and also supports cascading (e.g., AES-Serpent-Twofish).
It is based on Encryption for the Masses (E4M) 2.02a, conceived in 1997.
What's New in version 6.0a:
On systems where certain inappropriately designed chipset drivers were installed, it was impossible to encrypt the system partition/drive. This will no longer occur. (Windows Vista/XP/2008/2003)
Other minor bug fixes. (Windows, Mac OS X, and Linux)
