On a computer that is running Windows Server 2008 or Windows Vista, the certificates and the cryptographic keys are unusable after the user password is changed on another network computer

On a computer that is running Windows Vista or Windows Server 2008, the certificates and the cryptographic keys may be unusable after the user password is changed on another network computer. This problem mainly affects portable computer users in the following general situation:

• The user locks and unlocks her home computer to update the password while she is connected to the corporate network through a virtual private network (VPN) connection.
• Then, the user disconnects from the corporate network.

In this scenario, all the certificates and private cryptographic keys on the computer are unusable until the user logs back on to the corporate network.

For example, consider the following specific scenario:

• You have two computers. One is at the office, and the other is at home.
• You change the domain password on the office computer.
• You log on to the home computer by using cached domain credentials. These cached credentials include the old password.
• You connect to the corporate network from the home computer through a VPN connection. In this scenario, you must lock and then unlock the computer to update the password.
• You use the new password to restart and log on to the computer (not the corporate network) again.

In this scenario, all the certificates and private cryptographic keys are unusable until you connect to the corporate network again. Additionally, if you run an application that calls the CryptAcquireContext function, you may receive an error message that resembles the following:

In Windows Server 2008 and in Windows Vista, the certificates and cryptographic keys are protected by a master key. This master key, in turn, is protected by using an algorithm that is based on the user's password. When a password change occurs on another computer, and the user logs on to the domain by using cached credentials (the old password), the user is prompted to lock and unlock the computer by using the new password. It is expected that this action will update the password cache and re-encrypt the master key. However, only the password cache is updated. The master key is not re-encrypted by using the new password. Therefore, if the user logs off without accessing the key after the password is changed, the certificates and the cryptographic keys are unusable.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Important Windows Vista and Windows Server 2008 hotfixes are included in the same packages. However, only one of these products may be listed on the �Hotfix Request� page. To request the hotfix package that applies to both Windows Vista and Windows Server 2008, just select the product that is listed on the page.

Prerequisites

To apply this hotfix, you must have Windows Server 2008 installed on the computer.

Restart requirement

You have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other previously released hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2008 and Windows Vista file information

The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately . MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical to maintaining the state of the updated component. The security catalog files (attributes not listed) are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows Server 2008 and of Windows Vista

For all supported x64-based versions of Windows Server 2008 and of Windows Vista

For all supported Itanium-based versions of Windows Server 2008

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about the CryptAcquireContext function, visit the following Microsoft Web site: For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Additional file information for Windows Server 2008

Additional files for all supported x86-based versions of Windows Server 2008 and of Windows Vista

Additional files for all supported x64-based versions of Windows Server 2008 and of Windows Vista

Additional files for all supported Itanium-based versions of Windows Server 2008