BitLocker 设备加密（又译 BitLocker 驱动器加密）是 Microsoft Windows 操作系统在 Windows Vista 内首次提供的一项数据保护功能。后来的 Windows 版本不断改进 BitLocker 保护锁提供的安全性，从而允许操作系统为更多驱动器和设备提供 BitLocker 保护。将 BitLocker 与操作系统集成后，可以消除由于计算机丢失、被盗或解除授权不当而导致的数据被盗或公开的威胁。

当计算机有可信平台模块硬件的时候，BitLocker 驱动器加密会使用这个硬件。

BitLocker (codenamed Cornerstone and formerly known as Secure Startup) is a full disk encryption feature included with select editions of Windows Vista and later. It is designed to protect data by providing encryption for entire volumes. By default it uses the AES encryption algorithm in cipher block chaining (CBC) or XTS mode with a 128-bit or 256-bit key, and also the Elephant diffuser (on Windows Vista and Windows 7) for additional disk encryption security not provided by AES. CBC is not used over the whole disk, only for each individual disk sector.