The Clear method of the Win32_Tpm class resets the TPM to its factory-default state. A TPM owner can use this method to cancel TPM ownership and invalidate cryptographic materials created by the previous owner.

Warning  By clearing the TPM, you will lose all TPM keys created and used by applications. If these keys were used to encrypt data, ensure that you have another way to access the data before clearing the TPM.

Syntax

uint32 Clear(
  [in]  string OwnerAuth
);

Parameters

OwnerAuth [in]

A string that identifies the TPM owner. This string must be a base64-encoded string that contains exactly 20 bytes of binary data. Use the ConvertToOwnerAuth method to translate a passphrase to this expected format.

Return Value

All TPM errors as well as errors specific to TPM Base Services can be returned.

The following table lists some of the common return codes.

Remarks

Running this method can help prepare a TPM-equipped computer for recycling.

To clear the TPM but no longer have the TPM owner authorization, you need physical access to the computer. The SetPhysicalPresenceRequest method includes functionality to help clear the TPM without TPM owner authorization.

Managed Object Format (MOF) files contain the definitions for Windows Management Instrumentation (WMI) classes. MOF files are not installed as part of the Windows SDK. They are installed on the server when you add the associated role by using the Server Manager. For more information about MOF files, see Managed Object Format (MOF).

Requirements

See Also

Win32_Tpm

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Build date: 11/16/2009