Windows Internals, Fifth Edition

BitLocker Drive Encryption

An operating system can enforce its security policies only while it’s active, so you have to take additional measures to protect data when the physical security of a system can be compromised and the data accessed from outside the operating system. Hardware-based mechanisms such as BIOS passwords and encryption are two technologies commonly used to prevent unauthorized access, especially on laptops, which are the computers most likely to be lost or stolen.

While Windows supports the Encrypting File System (EFS), you can’t use EFS to protect access to sensitive areas of the system, such as the registry hive files. For example, if Group Policy allows you to log on to your laptop even when you’re not connected to a domain, ...