Article ID: 329741 - View products that this article applies to.
This article was previously published under Q329741
If you view Encrypting File System (EFS) files on a computer that is running Windows Server 2003, Windows XP, or Windows 2000, the encrypted files may appear to be corrupted or filled with random characters.
This behavior occurs if these files were encrypted on a computer that was running Windows XP Service Pack 1 (SP1) or later or Windows Server 2003. By default, Windows XP SP1 (or later) and Windows Server 2003 use the Advanced Encryption Standard (AES) algorithm for encrypting files with EFS. Windows 2000 and Windows XP do not support the AES algorithm and cannot access these files.
To resolve this behavior, access the encrypted files by using Windows XP SP1 (or later) or Windows Server 2003.
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:
(http://support.microsoft.com/kb/322756/ )How to back up and restore the registry in Windows
To work around this behavior, configure the Windows XP SP1-based computer to encrypt files by using an algorithm that is supported by the other operating systems that access the files. To do so:
EFS generates a new symmetric key called a File Encryption Key (FEK) for each file it encrypts. EFS uses this symmetric key to encrypt and decrypt the contents of the file. This FEK is then encrypted using the public keys in the certificates of the following users:
For more information about the AES Cryptographic Provider in Windows, visit the following Microsoft Web sites:
http://msdn2.microsoft.com/en-us/library/aa386983.aspxFor more information about EFS, view the Encrypting File System in Windows XP and Windows Server 2003 white paper. To view this white paper, visit the following Microsoft Web site:
Article ID: 329741 - Last Review: September 14, 2007 - Revision: 10.9