How to Clear TPM Information on a ThinkPad Laptop

I use a ThinkPad X200 laptop. Recently, while studying TPM on Windows, I found that to obtain the public part of the EK, I had to clear the TPM. A classmate's machine with an Infineon TPM can clear some TPM information through the BIOS, but the X200 BIOS does not show this option directly. It is actually there, just hidden. Here is how to clear it.

Press F1 during startup to enter the BIOS.

Go to the TPM settings page. The path is usually under a Security-related menu; look for Security Chip or a TPM settings item.

After entering the TPM settings page, you can see that the current status is Active.

First change the status to something other than Active. The available statuses include Active, Inactive, and Disable; here you can change it to Disable.

Then press F10 to save the settings. After confirmation, the machine will automatically restart.

After restarting, enter the BIOS TPM settings page again in the same way, and change the status back to Active.

After confirming, do not press F10; instead, press the power button to force the machine to shut down.

After shutdown, power it on again and enter the TPM settings screen once more. The hidden Clear Security Chip option will now appear.

After confirmation, all TPM key information will be cleared (except the EK), and Ownership will no longer exist. Pay attention to the note beside this item in the BIOS: if you have important data, be sure to back it up first. Otherwise, after the keys are cleared, data encrypted with those keys may no longer be decryptable.

Finally, press F10 to save and restart.

After clearing it, you can study the TPM in its initial state. However, each time the machine starts, Client Security Solution will prompt you to enter a password to restore keys and Take Ownership. At that point, you can cancel and skip it.

Original source:

<http://www.cnblogs.com/cxun/archive/2009/10/19/1586209.html>