The certificate validation fails on client computers when Internet Explorer 6 uses CAPI to retrieve the CRL or the CA certificates

You configure a proxy server that uses basic authentication or digest authentication in the network. The client computers can access the Internet through the proxy server. In this scenario, you may notice that the certificate validation on the client computers fails when Microsoft Internet Explorer 6 validates the certificate by using Cryptography API (CAPI) to retrieve the Certificate Revocation List (CRL). This problem also occurs when Internet Explorer 6 updates the certificates from certification authority (CA).

When you check the network traffic in the Microsoft Network Monitor, you will find the following error message:

This issue occurs because that the proxy server cannot authenticate the user credential when CAPI tries to retrieve the CRL or tries to update the certificates from CA.

On Windows XP SP2 and other advanced operating systems, the CAPI certificate uses the WinHTTP.dll process instead of the WinINet.dll process for network retrieval. The user credential is not shared in memory between WinINet.dll and WinHTTP.dll in Internet Explorer. The WinHTTP.dll process is noninteractive. The WinHTTP.dll process does not prompt the user for user credential. Therefore, when CAPI communicates with the proxy server over WinHTTP.dll, the proxy authentication fails because the user credential is unavailable.

Note This fix is included in Internet Explorer 7. However, to enable the fix, you still need the ShareCredsWithWinHttp registry key that is discussed in the "Registry information" section.

Hotfix information

Windows XP

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.

Prerequisites

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 any other hotfixes.

Registry information

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.

Create and then enable the ShareCredsWithWinHttp registry entry after you apply this hotfix. To do this, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings
3. Right-click the registry subkey, point to New, and then click DWORD Value.
4. Type ShareCredsWithWinHttp, and then press ENTER.
5. Right-click ShareCredsWithWinHttp, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Exit Registry Editor.

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 XP with Service Pack 2, x86-based versions

Windows Server 2003

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.

Prerequisites

To apply this hotfix, you must have Windows Server 2003 Service Pack 1 (SP1) installed on the computer.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

Registry information

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.

To enable this hotfix, add the ShareCredsWithWinHttp registry entry. To do this, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings
3. Right-click the registry subkey, point to New, and then click DWORD Value.
4. Type ShareCredsWithWinHttp, and then press ENTER.
5. Right-click ShareCredsWithWinHttp, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Exit Registry Editor.

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 2003 with Service Pack 1, x86-based versionsWindows Server 2003, x64-based versionsWindows Server 2003 with Service Pack 1, Itanium-based versions

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

After you apply this hotfix, WinINet.dll can send the user credential to WinHTTP.dll.

For more information about how to use Network Monitor to capture network traffic, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the changes to the CryptoAPI certificate chain validation logic in Windows XP Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the standard terminology that is used to describe Microsoft software updates, click the following article number to view the article in the Microsoft Knowledge Base: