[Update Nov. 11, 2014: The Truecrypt developers no longer support this product]
Since version 5, released on February 8, 2008, Truecrypt can encrypt an entire drive or partition, including the one that contains the operating system installation. Truecrypt’s implementation of strong drive encryption is particularly impressive. Listen to Security Now episode 133 for more information. Finally high quality free open source software is available for encrypting an entire hard disk. I immediately encrypted my Laptop’s hard disk. Truecrypt 4 was already installed and all private data was stored in an encrypted volume. Full disk encryption with pre-boot authentication is a much better solution though. Now the entire hard disc contains nothing that anyone could ever read. The encryption ran as a background process while I was surfing the web and took 2.5 hours on an 80 gb hard disk.
Don’t leave the data on your portable computer unprotected. Download Truecrypt for your PC, Linux box or Mac.
Free encryption software (1): Introduction
Free encryption software (2): File encryption on USB flash drives
Free encryption software (4): GNU Privacy Guard