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Setting the BitLocker encryption algorithm for Autopilot devices

BitLocker automatically encrypts internal drives during the out of box experience (OOBE) for devices that support Modern Standby or meet the Hardware Security Testability Specification (HSTI). By default, BitLocker uses XTS-AES 128-bit used space only for automatic encryption.

With Windows Autopilot, you can configure BitLocker encryption settings to apply before automatic encryption starts. This configuration makes sure the default encryption algorithm or type isn't applied automatically. A device that receives these settings after encrypting automatically will need to be decrypted before changing the encryption algorithm.

Encryption algorithm

The BitLocker encryption algorithm is used when BitLocker is first enabled. During Autopilot, BitLocker will be enabled after the device setup portion of the enrollment status page. The following encryption algorithms are available:

  • AES-CBC 128-bit
  • AES-CBC 256-bit
  • XTS-AES 128-bit (default)
  • XTS-AES 256-bit

For more information about the recommended encryption algorithms to use, see BitLocker CSP.

To make sure the BitLocker encryption algorithm you want is set before automatic encryption occurs for Autopilot devices:

  1. Configure the encryption method settings in the Endpoint Security disk encryption policy. The settings are available under Endpoint Security > Disk encryption > Create policy > Platform = Windows 10 and later, Profile type = BitLocker.

  2. Assign the policy to your Autopilot device group. The encryption policy must be assigned to devices in the group, not users.

  3. Enable the Autopilot enrollment status page for these devices. If you don't enable this feature, the policy won't apply before encryption starts.

Full disk or used space-only encryption

There are two types of encryption, full disk or used space-only. The type of encryption is automatically determined by configuration of silent enablement and hardware support for modern standby. You can enforce it by configuring the SystemDrivesEncryptionType setting. Like the encryption algorithm, the encryption type is used when BitLocker is first enabled. For more information on the expected encryption type behavior, see Manage BitLocker policy.

To enforce the type of drive encryption used:

  1. Configure the Enforce drive encryption type on operating system drives setting within the settings catalog. This setting is available in the Administrative Templates > Windows Components > BitLocker Drive Encryption > Operating System Drives category from the settings picker.

  2. Assign the policy to your Autopilot device group. The encryption policy must be assigned to devices in the group, not users.

  3. Enable the Autopilot enrollment status page for these devices. If you don't enable this feature, the policy won't apply before encryption starts.

Requirements

A supported version of Windows.

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