What is BitLocker Key Rotation Eactly and How to Realize It

BitLocker is a full disk encryption feature built into Windows. While BitLocker doesn't have an explicit "key rotation" feature, administrators can take several steps to manage recovery key backup, re-encryption, and key protector policies effectively.

Let's dive into BitLocker key rotation by definition, including how to manage BitLocker key rotation employing Group Policy, PowerShell, and Intune.

Reddit discussion on BitLocker key rotation

In Microsoft Intune, BitLocker recovery key rotation is not automatic. Administrators must manually initiate the rotation for each device. The Intune documentation specifies that to rotate the BitLocker recovery key, an administrator needs to select the device and choose the rotate BitLocker recovery key option.

Bitlocker AUTOMATIC key rotation?
by u/Real_Lemon8789 in Intune

From the intensive discussion on Reddit, currently, there is no Microsoft documentation indicating that Intune-managed systems will automatically rotate BitLocker recovery keys without administrative intervention. Key rotation must be manually triggered by an administrator for each device as needed.

To straighten these things up. We devise this article to show a clear explanation of BitLocker key rotation based on real user reviews and assist you with a comprehensive guide to carry the rotation. Just keep reading.

What is BitLocker key rotation?

BitLocker key rotation refers to the process of refreshing or changing the BitLocker recovery key or encryption key. While there is no direct "key rotation" option in BitLocker itself, administrators can rotate keys by re-encrypting the drive, regenerating new recovery keys, or periodically updating key protectors. Key rotation is important for maintaining security, especially when drives are frequently encrypted, decrypted, or managed remotely.

How to manage BitLocker key rotation via Group Policy

Group Policy (GPO) can be used to enforce settings that indirectly support key rotation and ensure the recovery keys are properly managed and backed up to a secure location like Active Directory (AD). Below are key GPO settings related to BitLocker recovery key management:

1. Backing up BitLocker recovery keys to Active Directory (AD)

To ensure that BitLocker recovery keys are securely stored and accessible, administrators can configure Group Policy to automatically back up recovery information to Active Directory. This allows an administrator to retrieve the key in case of an emergency, such as when a user forgets their PIN or password.

Steps to configure Group Policy for backing up BitLocker recovery keys to AD:

By enforcing this GPO, you ensure that every BitLocker-enabled device automatically saves its recovery key in AD, providing a secure backup mechanism for key management.

2. Triggering re-encryption to rotate the encryption key

While BitLocker does not have a built-in key rotation policy, re-encryption can be used as a workaround to regenerate a new encryption key. Re-encrypting the disk triggers the generation of a new encryption key, thus effectively rotating the key.

Re-encryption can be performed manually or through automated tools like PowerShell or Intune. Here's how you can force re-encryption of a drive via PowerShell (You can open it by pressing Windows + S, then type PowerShell and select Windows PowerShell, then type the following command and press Enter):# Re-encrypt the C: drive to trigger key rotation 
Enable-BitLocker -MountPoint "C:" -EncryptionMethod Aes256 -UsedSpaceOnly

This action will create a new encryption key and may be required periodically based on your organization's security policies.

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Managing BitLocker key rotation via PowerShell

PowerShell provides a powerful way to manage BitLocker encryption and recovery keys. While Group Policy controls the key backup and encryption settings, PowerShell allows administrators to rotate and regenerate keys directly.

1. Retrieve the current BitLocker recovery key

To see the current recovery key for a drive, you can use the following PowerShell cmdlet:# Retrieve current BitLocker key protector for the C: drive 
(Get-BitLockerVolume -MountPoint "C:").KeyProtector

2. Remove and add new key protectors

If you want to rotate the key by removing an old key protector and adding a new one, use the following commands as a whole:

# List all protectors for C: drive 
Get-BitLockerVolume -MountPoint "C:" | Select-Object -ExpandProperty KeyProtector

# Remove an existing key protector 
Remove-BitLockerKeyProtector -MountPoint "C:" -KeyProtectorId "ID_of_the_Key_Protector"

# Add a new recovery key protector 
Add-BitLockerKeyProtector -MountPoint "C:" -RecoveryPassword

3. Force re-encryption via PowerShell 

To trigger re-encryption and force a key rotation, you can use the following PowerShell command:# Re-encrypt the C: drive to generate a new encryption key 
Enable-BitLocker -MountPoint "C:" -EncryptionMethod Aes256 -UsedSpaceOnly

This forces the drive to re-encrypt, which regenerates the encryption key and ensures that the new recovery key is backed up (if configured).

BitLocker key management with Intune

For Azure AD-joined or domain-joined devices managed with Microsoft Intune, BitLocker key rotation can be more easily managed. Intune allows administrators to configure BitLocker settings, enforce recovery key backup, and even re-encrypt devices to rotate keys.

1. Configure BitLocker in Intune

In Intune, you can configure BitLocker settings, including policies for enabling encryption and storing recovery keys. Once devices are encrypted, re-encryption can be initiated to generate new keys. Here's how to configure BitLocker in Intune:

2. Automate BitLocker recovery key rotation in Intune

To automate the rotation of recovery keys, Intune can force a new recovery key or trigger re-encryption if needed. Intune's integration with Azure AD allows you to store recovery keys in the cloud, providing an additional layer of security and simplifying key management.

To enable automatic BitLocker recovery key rotation in Microsoft Intune, follow these steps:

By completing these steps, Intune will automatically handle the rotation of BitLocker recovery keys after they are used, enhancing the security of your devices.

Conclusion

While BitLocker key rotation isn't a built-in feature, administrators can effectively manage key rotation by using a combination of Group Policy, PowerShell, and Intune. Here's a summary of key techniques:

1. Ensure that recovery keys are backed up to Active Directory or Azure AD through Group Policy. 2. Trigger re-encryption via PowerShell or Intune to rotate the encryption key and generate a new recovery key. 3. There is automated key management by leveraging Intune to enforce policies and re-encrypt devices.

By combining these methods, you can ensure that your BitLocker encryption is properly managed and that recovery keys are securely stored and periodically rotated to maintain a high level of security. Also read How to Harness PowerShell to Enable BitLocker and Understanding GPO BitLocker: Features and Capabilities

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