# Windows Bitlocker Strength

By default Windows 7/8 Bitlocker uses 128-bit encryption. Each version has an option for 256-bit <span class="caps">AES</span> encryption. The change to 256-bit requires a Windows policy modification.

See also—

- Bitlocker Step-by-Step Guide, [http://go.microsoft.com/fwlink/?LinkId=53779](http://go.microsoft.com/fwlink/?LinkId=53779)
- Note for Vista and 7, [http://windows.microsoft.com/en-US/windows-vista/What-is-the-difference-between-BitLocker-Drive-Encryption-128-bit-and-256-bit-encryption](http://windows.microsoft.com/en-US/windows-vista/What-is-the-difference-between-BitLocker-Drive-Encryption-128-bit-and-256-bit-encryption)
- Bitlocker strength and unlock methods, [https://technet.microsoft.com/en-us/library/ee706531(v=ws.10).aspx](https://technet.microsoft.com/en-us/library/ee706531(v=ws.10).aspx)