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Clear-Tpm

Windows Server 2012 R2 and Windows 8.1

Updated: October 17, 2013

Applies To: Windows 8.1, Windows PowerShell 4.0, Windows Server 2012 R2

Clear-Tpm

Resets a TPM to its default state.

Syntax

Parameter Set: Owner Auth
Clear-Tpm [[-OwnerAuthorization] <String> ] [ <CommonParameters>]

Parameter Set: File
Clear-Tpm -File <String> [ <CommonParameters>]




Detailed 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 at http://technet.microsoft.com/en-us/library/jj131725.aspx.

Parameters

-File<String>

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


Aliases

none

Required?

true

Position?

named

Default Value

none

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-OwnerAuthorization<String>

Specifies the current owner authorization value for the TPM.


Aliases

none

Required?

false

Position?

2

Default Value

none

Accept Pipeline Input?

true (ByValue)

Accept Wildcard Characters?

false

<CommonParameters>

This cmdlet supports the common parameters: -Verbose, -Debug, -ErrorAction, -ErrorVariable, -OutBuffer, and -OutVariable. For more information, see    about_CommonParameters.

Inputs

The input type is the type of the objects that you can pipe to the cmdlet.

  • String

    The owner authorization value for the TPM.


Outputs

The output type is the type of the objects that the cmdlet emits.

  • TpmObject

    A TpmObject object contains the following information:

    -- TpmReady. Whether a TPM complies with Windows Server® 2012 standards.
    -- TpmPresent. Whether there is a TMP 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.


Examples

Example 1: Reset TPM

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.


PS C:\> Clear-Tpm
TpmReady           : False
TpmPresent : True
ManagedAuthLevel : Full
OwnerAuth :
OwnerClearDisabled : True
AutoProvisioning : Disabled
LockedOut : False
SelfTest : {191, 191, 245, 191...}

Example 2: Reset TPM with a supplied authorization value

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


PS C:\> Clear-Tpm -OwnerAuthorization "vjnuW6rToM41os3xxEpjLdIW2gA="
TpmReady           : False
TpmPresent : True
ManagedAuthLevel : Full
OwnerAuth : OwnerClearDisabled : True
AutoProvisioning : Disabled
LockedOut : False
SelfTest : {191, 191, 245, 191...}

Example 3: Reset TMP using authorization value from file

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


PS C:\> Clear-Tpm -File "MyOwnerAuthFile.tpm"
TpmReady           : False
TpmPresent : True
ManagedAuthLevel : Full
OwnerAuth :
OwnerClearDisabled : True
AutoProvisioning : Disabled
LockedOut : False
SelfTest : {191, 191, 245, 191...}

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