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Added a note about temporary halting encryption

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Paolo Matarazzo 2025-04-28 15:33:24 -04:00
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windows/security/operating-system-security/data-protection/bitlocker/index.md
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@ -2,7 +2,7 @@
title: BitLocker overview title: BitLocker overview
description: Learn about BitLocker practical applications and requirements. description: Learn about BitLocker practical applications and requirements.
ms.topic: overview ms.topic: overview
ms.date: 12/05/2024 ms.date: 04/28/2025
--- ---
# BitLocker overview # BitLocker overview
@ -21,8 +21,8 @@ In *addition* to the TPM, BitLocker can lock the normal startup process until th
On devices that don't have a TPM, BitLocker can still be used to encrypt the operating system drive. This implementation requires the user to either: On devices that don't have a TPM, BitLocker can still be used to encrypt the operating system drive. This implementation requires the user to either:
- use a startup key, which is a file stored on a removable drive that is used to start the device, or when resuming from hibernation - Use a startup key, which is a file stored on a removable drive that is used to start the device, or when resuming from hibernation.
- use a password. This option isn't secure since it's subject to brute force attacks as there isn't a password lockout logic. As such, the password option is discouraged and disabled by default - Use a password. This option isn't secure since it's subject to brute force attacks as there isn't a password lockout logic. As such, the password option is discouraged and disabled by default.
Both options don't provide the preboot system integrity verification offered by BitLocker with a TPM. Both options don't provide the preboot system integrity verification offered by BitLocker with a TPM.
@ -53,9 +53,9 @@ Both options don't provide the preboot system integrity verification offered by
BitLocker has the following requirements: BitLocker has the following requirements:
- For BitLocker to use the system integrity check provided by a TPM, the device must have TPM 1.2 or later versions. If a device doesn't have a TPM, saving a startup key on a removable drive is mandatory when enabling BitLocker - For BitLocker to use the system integrity check provided by a TPM, the device must have TPM 1.2 or later versions. If a device doesn't have a TPM, saving a startup key on a removable drive is mandatory when enabling BitLocker.
- A device with a TPM must also have a *Trusted Computing Group* (TCG)-compliant BIOS or UEFI firmware. The BIOS or UEFI firmware establishes a chain of trust for the preboot startup, and it must include support for *TCG-specified Static Root of Trust Measurement*. A computer without a TPM doesn't require TCG-compliant firmware - A device with a TPM must also have a *Trusted Computing Group* (TCG)-compliant BIOS or UEFI firmware. The BIOS or UEFI firmware establishes a chain of trust for the preboot startup, and it must include support for *TCG-specified Static Root of Trust Measurement*. A computer without a TPM doesn't require TCG-compliant firmware.
- The system BIOS or UEFI firmware (for TPM and non-TPM devices) must support the USB mass storage device class, and reading files on a USB drive in the preboot environment - The system BIOS or UEFI firmware (for TPM and non-TPM devices) must support the USB mass storage device class, and reading files on a USB drive in the preboot environment.
> [!NOTE] > [!NOTE]
> TPM 2.0 is not supported in *Legacy* and *Compatibility Support Module (CSM)* modes of the BIOS. Devices with TPM 2.0 must have their BIOS mode configured as native UEFI only. The Legacy and CSM options must be disabled. For added security, enable the *secure boot* feature. > TPM 2.0 is not supported in *Legacy* and *Compatibility Support Module (CSM)* modes of the BIOS. Devices with TPM 2.0 must have their BIOS mode configured as native UEFI only. The Legacy and CSM options must be disabled. For added security, enable the *secure boot* feature.
@ -63,12 +63,12 @@ BitLocker has the following requirements:
> Installed operating system on hardware in Legacy mode stops the OS from booting when the BIOS mode is changed to UEFI. Use the tool [`mbr2gpt.exe`][WIN-1] before changing the BIOS mode, which prepares the OS and the disk to support UEFI. > Installed operating system on hardware in Legacy mode stops the OS from booting when the BIOS mode is changed to UEFI. Use the tool [`mbr2gpt.exe`][WIN-1] before changing the BIOS mode, which prepares the OS and the disk to support UEFI.
- The hard disk must be partitioned with at least two drives: - The hard disk must be partitioned with at least two drives:
- The *operating system drive* (or boot drive) contains the OS and its support files. It must be formatted with the NTFS file system - The *operating system drive* (or boot drive) contains the OS and its support files. It must be formatted with the NTFS file system.
- The *system drive* contains files required to boot, decrypt, and load the operating system. BitLocker isn't enabled on this drive. For BitLocker to work, the system drive: - The *system drive* contains files required to boot, decrypt, and load the operating system. BitLocker isn't enabled on this drive. For BitLocker to work, the system drive:
- must not be encrypted - must not be encrypted.
- must differ from the operating system drive - must differ from the operating system drive.
- must be formatted with the FAT32 file system on computers that use UEFI-based firmware, or with the NTFS file system on computers that use BIOS firmware - must be formatted with the FAT32 file system on computers that use UEFI-based firmware, or with the NTFS file system on computers that use BIOS firmware.
- it's recommended that to be approximately 350 MB in size. After BitLocker is turned on, it should have approximately 250 MB of free space - it's recommended that to be approximately 350 MB in size. After BitLocker is turned on, it should have approximately 250 MB of free space.
> [!IMPORTANT] > [!IMPORTANT]
> When installed on a new device, Windows automatically creates the partitions that are required for BitLocker. > When installed on a new device, Windows automatically creates the partitions that are required for BitLocker.
@ -93,11 +93,11 @@ BitLocker has the following requirements:
Unlike a standard BitLocker implementation, device encryption is enabled automatically so that the device is always protected. When a clean installation of Windows is completed and the out-of-box experience is finished, the device is prepared for first use. As part of this preparation, device encryption is initialized on the OS drive and fixed data drives on the computer with a clear key that is the equivalent of standard BitLocker suspended state. In this state, the drive is shown with a warning icon in Windows Explorer. The yellow warning icon is removed after the TPM protector is created and the recovery key is backed up. Unlike a standard BitLocker implementation, device encryption is enabled automatically so that the device is always protected. When a clean installation of Windows is completed and the out-of-box experience is finished, the device is prepared for first use. As part of this preparation, device encryption is initialized on the OS drive and fixed data drives on the computer with a clear key that is the equivalent of standard BitLocker suspended state. In this state, the drive is shown with a warning icon in Windows Explorer. The yellow warning icon is removed after the TPM protector is created and the recovery key is backed up.
- If the device is Microsoft Entra joined or Active Directory domain joined, the clear key is removed once the recovery key is successfully backed up to Microsoft Entra ID or Active Directory Domain Services (AD DS). The following policy settings must be enabled for the recovery key to be backed up: [Choose how BitLocker-protected operating system drives can be recovered](configure.md?tabs=os#choose-how-bitlocker-protected-operating-system-drives-can-be-recovered) - If the device is Microsoft Entra joined or Active Directory domain joined, the clear key is removed once the recovery key is successfully backed up to Microsoft Entra ID or Active Directory Domain Services (AD DS). The following policy settings must be enabled for the recovery key to be backed up: [Choose how BitLocker-protected operating system drives can be recovered](configure.md?tabs=os#choose-how-bitlocker-protected-operating-system-drives-can-be-recovered).
- For Microsoft Entra joined devices: the recovery password is created automatically when the user authenticates to Microsoft Entra ID, then the recovery key is backed up to Microsoft Entra ID, the TPM protector is created, and the clear key is removed - For Microsoft Entra joined devices: the recovery password is created automatically when the user authenticates to Microsoft Entra ID, then the recovery key is backed up to Microsoft Entra ID, the TPM protector is created, and the clear key is removed.
- For AD DS joined devices: the recovery password is created automatically when the computer joins the domain. The recovery key is then backed up to AD DS, the TPM protector is created, and the clear key is removed - For AD DS joined devices: the recovery password is created automatically when the computer joins the domain. The recovery key is then backed up to AD DS, the TPM protector is created, and the clear key is removed.
- If the device isn't Microsoft Entra joined or Active Directory domain joined, a Microsoft account with administrative privileges on the device is required. When the administrator uses a Microsoft account to sign in, the clear key is removed, a recovery key is uploaded to the online Microsoft account, and a TPM protector is created. Should a device require the recovery key, the user is guided to use an alternate device and navigate to a recovery key access URL to retrieve the recovery key by using their Microsoft account credentials - If the device isn't Microsoft Entra joined or Active Directory domain joined, a Microsoft account with administrative privileges on the device is required. When the administrator uses a Microsoft account to sign in, the clear key is removed, a recovery key is uploaded to the online Microsoft account, and a TPM protector is created. Should a device require the recovery key, the user is guided to use an alternate device and navigate to a recovery key access URL to retrieve the recovery key by using their Microsoft account credentials.
- If a device uses only local accounts, then it remains unprotected even though the data is encrypted - If a device uses only local accounts, then it remains unprotected even though the data is encrypted.
> [!IMPORTANT] > [!IMPORTANT]
> Device encryption uses the `XTS-AES 128-bit` encryption method, by default. In case you configure a policy setting to use a different encryption method, you can use the Enrollment Status Page to avoid the device to begin encryption with the default method. BitLocker has a logic that doesn't start encrypting until the end of OOBE, after the Enrollment Status Page device configuration phase is complete. This logic gives a device enough time to receive the BitLocker policy settings before starting encryption. > Device encryption uses the `XTS-AES 128-bit` encryption method, by default. In case you configure a policy setting to use a different encryption method, you can use the Enrollment Status Page to avoid the device to begin encryption with the default method. BitLocker has a logic that doesn't start encrypting until the end of OOBE, after the Enrollment Status Page device configuration phase is complete. This logic gives a device enough time to receive the BitLocker policy settings before starting encryption.
@ -112,11 +112,14 @@ You can check whether a device meets requirements for device encryption in the S
|-|-| |-|-|
|Device Encryption Support | Meets prerequisites| |Device Encryption Support | Meets prerequisites|
> [!NOTE]
> If Windows detects user activity during encryption, automatic device encryption might be delayed or temporarily halted; this is particularly true if the device is operating on battery to conserve power.
### Difference between BitLocker and device encryption ### Difference between BitLocker and device encryption
- Device encryption turns on BitLocker automatically on device encryption-qualifying devices, with the recovery key automatically backed up to Microsoft Entra ID, AD DS, or the user's Microsoft account - Device encryption turns on BitLocker automatically on device encryption-qualifying devices, with the recovery key automatically backed up to Microsoft Entra ID, AD DS, or the user's Microsoft account.
- Device encryption adds a device encryption setting in the Settings app, which can be used to turn device encryption on or off - Device encryption adds a device encryption setting in the Settings app, which can be used to turn device encryption on or off.
- The Settings UI doesn't show device encryption enabled until encryption is complete - The Settings UI doesn't show device encryption enabled until encryption is complete.
:::image type="content" source="images/settings-device-encryption.png" alt-text="Screenshot of the Settings app showing the device encryption panel." border="False"::: :::image type="content" source="images/settings-device-encryption.png" alt-text="Screenshot of the Settings app showing the device encryption panel." border="False":::