Truecrypt is a cross-platform, free disk encryption software for Windows and Unix-like operating systems. It is generally considered a good disk encryption software, and not too long ago, I wrote a tutorial that showed how to encrypt the Windows installation of a Windows-Linux dual-boot setup (see Dual-boot Fedora 18 and Windows 7, with full disk encryption configured on both OSs). Truecrypt is said to be published under an open source license, but in some quarters, its license has not been accepted as a valid open source license. And some of those people believe it has a backdoor. Guess who is...