A hard drive encryption tool in Microsoft Windows that began with Windows Vista Enterprise and Ultimate. BitLocker addresses threats of data theft or disclosure from lost, stolen or inappropriately decommissioned PC hardware. BitLocker works by preventing a thief who boots another operating system or runs a software hacking tool from breaking Windows Vista file and system protections or performing offline viewing of the files stored on the protected drive. The feature uses a Trusted Platform Module to protect user data and to ensure that a PC running Windows Vista has not been tampered with while the system was offline. BitLocker combines drive encryption and integrity checking of early boot components.
Also see Windows Vista.