Encrypting File System (EFS) generates a self-signed certificate when you try to encrypt an EFS file on a Windows XP-based computer

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Microsoft ended support for Windows XP on April 8, 2014. This change has affected your software updates and security options. Learn what this means for you and how to stay protected.

This article has been archived. It is offered "as is" and will no longer be updated.
Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
Consider the following scenario:
  • You try to encrypt an Encrypting File System (EFS) file on a Windows XP-based computer.
  • No EFS certificate is available in the local certificate store.
  • No certification authority (CA) is available to issue an EFS certificate.
In this scenario, EFS generates a self-signed certificate. Then, EFS uses this self-signed certificate to encrypt the file.

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.


To apply this hotfix, you must have Windows XP Service Pack 2 (SP2) installed on the computer.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

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.
File nameFile versionFile sizeDateTimePlatformSP requirementService branch
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
After you apply the hotfix, you can prevent EFS from generating self-signed certificates. To do this, follow these steps.

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
  1. Click Start, click Run, type regedit, and then click OK.
  2. Locate and then click the following registry subkey:
    HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\CurrentVersion\EFS
  3. On the Edit menu, point to New, and then click DWORD Value.
  4. Type EfsOptions, and then press ENTER.
  5. Double-click
    , type 0 in the Value data box, and then click OK.
  6. Exit Registry Editor.
After you add the EfsOptions registry value, you must create a custom Administrative Template to define a new policy. This new policy will centrally manage the registry change. To do this, follow these steps:
  1. Start Notepad.
  2. Enter the following text.
    CLASS MACHINE CATEGORY "System" CATEGORY "Public Key Policies"POLICY "Encrypted File System" KEYNAME "Software\Policies\Microsoft\Windows NT\CurrentVersion\EFS"PART "Allow EFS to Generate Selfsigned Certificate when a Certificate Authority is not available" CHECKBOX VALUENAME "EfsOptions"VALUEON NUMERIC 4VALUEOFF NUMERIC 0END PART END POLICY END CATEGORY END CATEGORY 
  3. On the File menu, click Save As.
  4. In the Save as typelist, click All Files.
  5. Type %windir%\inf\efscustom.adm in the File name box, and then click Save.

    Note The %windir% placeholder represents the drive letter of the Windows system folder.
  6. Exit Notepad.
  7. Restart the computer.
Note After you apply this hotfix, you may still experience the old behavior if the EfsOptions registry value is missing or is set to a value of 4.

For more information about how to create custom Administrative Templates, click the following article number to view the article in the Microsoft Knowledge Base:
323639 How to create custom Administrative Templates in Windows 2000
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
930499 You cannot prevent EFS from generating a self-signed certificate when you try to encrypt an EFS file on a Windows Server 2003-based computer
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates
efs certificate self signed

Article ID: 912761 - Last Review: 12/09/2015 04:15:21 - Revision: 6.0

Microsoft Windows XP Professional, Microsoft Windows XP Home Edition

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