Clear-Tpm

  • Reference
Module:
TrustedPlatformModule

Resets a TPM to its default state.

Syntax

Clear-Tpm
     [-UsePPI]
     [[-OwnerAuthorization] <String>]
     [<CommonParameters>]
Clear-Tpm
     -File <String>
     [<CommonParameters>]

Description

The Clear-Tpm cmdlet resets the Trusted Platform Module (TPM) to its default state. A reset removes the owner authorization value and any keys stored in the TPM. To reset a TPM, you must provide a valid owner authorization value. You can enter an owner authorization value or specify a file that contains the value. If you do not provide a value, the cmdlet attempts to use a value stored in the registry.

For more information on TPM, see the Trusted Platform Module Technology Overview in the TechNet library.

Examples

Example 1: Reset TPM

Clear-Tpm

TpmReady           : False
TpmPresent         : True
ManagedAuthLevel   : Full
OwnerAuth          :
OwnerClearDisabled : True
AutoProvisioning   : Disabled
LockedOut          : False
SelfTest           : {191, 191, 245, 191...}

This command resets the TPM. The command uses the owner authorization value stored in the registry instead of specifying a value or using a value in a file.

Example 2: Reset TPM with a supplied authorization value

Clear-Tpm -OwnerAuthorization "vjnuW6rToM41os3xxEpjLdIW2gA="

TpmReady           : False
TpmPresent         : True
ManagedAuthLevel   : Full
OwnerAuth          :
OwnerClearDisabled : True
AutoProvisioning   : Disabled
LockedOut          : False
SelfTest           : {191, 191, 245, 191...}

This command resets the TPM by using the specified owner authorization value.

Example 3: Reset TPM using authorization value from file

Clear-Tpm -File "MyOwnerAuthFile.tpm"

TpmReady           : False
TpmPresent         : True
ManagedAuthLevel   : Full
OwnerAuth          :
OwnerClearDisabled : True
AutoProvisioning   : Disabled
LockedOut          : False
SelfTest           : {191, 191, 245, 191...}

This command resets the TPM by using the owner authorization value included in the specified file.

Example 4: Reset TPM with Physical Presence Interface

Clear-Tpm -UsePPI

TpmReady           : False
TpmPresent         : True
ManagedAuthLevel   : Full
OwnerAuth          :
OwnerClearDisabled : True
AutoProvisioning   : Disabled
LockedOut          : False
SelfTest           : {191, 191, 245, 191...}

This command resets the TPM by using the Physical Presence Interface (PPI). The PPI does not use a value for owner authorization.

Restart the system for the clear action to take effect. The restart might require user input to approve the clear request.

Parameters

-File

Specifies a file that contains the current owner authorization value for the TPM. You can use the TPM Management Console to create this file.

Type:String
Position:Named
Default value:None
Required:True
Accept pipeline input:False
Accept wildcard characters:False

-OwnerAuthorization

Specifies the current owner authorization value for the TPM.

Type:String
Aliases:o
Position:1
Default value:None
Required:False
Accept pipeline input:True
Accept wildcard characters:False

-UsePPI

Use the PPI for the TPM reset. Restart the system for the changes to take effect. The restart might require user input to approve the clear request.

Type:SwitchParameter
Aliases:ppi
Position:Named
Default value:None
Required:False
Accept pipeline input:True
Accept wildcard characters:False

Inputs

String

This cmdlet accepts the owner authorization value for the TPM.

Outputs

TpmObject

This cmdlet returns a TpmObject object contains the following information:

  • TpmReady. Whether a TPM complies with Windows Server® 2012 standards.
  • TpmPresent. Whether there is a TPM on the current computer.
  • ManagedAuthLevel. The level at which the operating system manages the owner authorization. Possible values are Legacy, Balanced, and Full.
  • OwnerClearDisabled. Whether TPM can be reset. If this value is True, the TPM cannot be reset through the operating system by using the owner authorization value. If this value is False, the TPM can be reset through the operating system.
  • AutoProvisioning. Whether the computer can use auto-provisioning. Possible values are NotDefined, Enabled, Disabled, and DisabledForNextBoot.
  • LockedOut. Whether a TPM is locked out.
  • SelfTest. Information returned by a test that TPM runs.