A user name that contains Unicode characters is not handled correctly in Windows XP Service Pack 3 during the EAP authentication

When you use a user account that has a user name that contains Unicode characters on a Windows XP Service Pack 3 (SP3)-based computer, the username fails the Extensible Authentication Protocol (EAP) authentication. Therefore, you cannot access the local network.

This problem occurs because of the EAPHost architecture in Windows XP SP3. When you try to authenticate, the EAPHost converts the EAP ID message to Unicode. However, the server tries to read the EAP ID message as ASCII. Therefore, if the user identity has the ASCII characters 128 through 255, the EAP authentication fails.

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.

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, submit a request to 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 3 installed on the computer. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Restart requirement

Y ou do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

Registry information

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
To enable this hotfix, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EapHost\Configuration
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type IdentityEncodingFormat, and then press ENTER.
5. On the Edit menu, click Modify.
6. Type 0x1, 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 3, x86-based versions

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 EAPHost architecture, visit the following Web site: For more information about Internet Authentication Service (IAS), visit the following Web site: