TrueCrypt

 Executive Summary:

With the encryption tool TrueCrypt, unlike with other file-based security encryption products, you specify the maximum total size of the container when you first create it. TrueCrypt then encrypts the entire container, including unused free space within the container. For example, if you create a 1GB container but store only a few files totaling less than 100KB within the container, no one will be able to surmise the size or contents of the files in your container. TrueCrypt supports encryption of files and volumes on a flash drive, hard drive, CD-ROM, or DVD.

What sets the TrueCrypt encryption tool apart from other encryption programs is its ability to hide an encrypted volume within another encrypted volume for extra security. This means that if someone steals your flash drive, the thief won’t know how large your inner encrypted volume is or if the outer volume is actually a decoy—even if you’re forced to give up your password. TrueCrypt's transparency and ease of use lets you conduct on-the-fly encryption and decryption of your data files. Using this free, open-source encryption tool, you create an encrypted container on your hard drive, flash drive, or other storage media (e.g., CD-ROM, DVD), which you can use just like a typical local drive—your OS won’t know the difference. In TrueCrypt's traveler mode, you can run it directly from a flash drive on any computer for which you have administrator rights.
     
How TrueCrypt Works
The concept of TrueCrypt is straightforward: You run the program and create a container, which can be a single file or a partition or device. You enter the correct password or keyfile, and TrueCrypt permits the OS to mount the encrypted container as a local drive. Your OS can read and write data from the encrypted container as if it were a regular storage device, but the data always remains encrypted on the storage device. . . .