Windows BitLocker Drive Encryption Step-by-Step Guide

BitLocker Drive Encryption is an integral new security feature in the Windows Vista operating system that provides considerable off-line data and operating system protection for your computer. BitLocker ensures that data stored on a computer running Windows Vista is not revealed if the computer is tampered with when the installed operating system is offline. It optionally uses a Trusted Platform Module (TPM) to provide enhanced protection for your data and to assure early boot component integrity. This can help protect your data from theft or unauthorized viewing by encrypting the entire Windows volume.
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Source: Microsoft.com