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
When a user connects to your secure Web site by using https:// in Microsoft Internet Explorer 6, and your Web server requires client authentication, one of the following symptoms may occur:
Client certificates that contain the Key Usage (KU) extension may not be displayed.
Client certificates that contain the Key Usage (KU) extension are displayed when they should not be displayed.
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 the problem described in this article. 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.
There are no prerequisites required to install this hotfix.
You must restart your computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace any other hotfixes.
After you install this hotfix, you can customize the filtering of the list of client 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 the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
Exit Internet Explorer.
Click Start, click Run, type regedit, and then click OK.
Locate and then click to select one of the following registry subkeys:
After you select the subkey that is specified in step 3, right-click click on the right side of the Registry Editor user interface to add a new DWORD key value.
Type FEATURE_CLIENTAUTHCERTFILTER, and then press ENTER.
With the new DWORD feature key added, double-click the new DWORD feature key, and then add the appropriate DWORD value.
A certificate is considered valid for SSL client authentication if no Extended Key Usage extension is present, or is present and contains the Client Auth object identifier. In this mode, the Key Usage extension is ignored. This is the original filter that was used in Internet Explorer 6 (gold).
A certificate is considered valid for SSL client authentication if no Key Usage extension is present, or is present and not marked critical, or is present and marked critical and contains the Digital Signature bit. No Extended Key Usage extension is present, or is present and contains the Client Auth object identifier.
A certificate is considered valid for SSL client authentication if no Key Usage extension is present, or is present and contains the Digital Signature bit. No Extended Key Usage extension is present, or is present and contains the Client Auth object identifier. By default, this is the filter that is used after you install this hotfix. Additionally, this is the same filter that is installed by the hotfix that is described in Microsoft Knowledge Base article 811383. If the registry key is not set, the default filter (3) is used.
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.
Date Time Version Size File name ------------------------------------------------------- 14-Jan-2005 17:21 6.0.2800.1489 581,632 Wininet.dll
Microsoft has confirmed that this is a problem in Microsoft Internet Explorer 6.