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How To Use Cipher.exe to Overwrite Deleted Data in Windows
Article ID: 315672 - View products that this article applies to.
This article was previously published under Q315672
NoticeThis article applies to Windows 2000. Support for Windows 2000 ends on July 13, 2010. The Windows 2000 End-of-Support Solution Center
(http://support.microsoft.com/?scid=http%3a%2f%2fsupport.microsoft.com%2fwin2000)is a starting point for planning your migration strategy from Windows 2000. For more information see the Microsoft Support Lifecycle Policy
Administrators can use Cipher.exe to encrypt and decrypt data on drives that use the NTFS file system and to view the encryption status of files and folders from a command prompt. An updated version of the Cipher tool has been released for Windows 2000, and is included with Windows XP. The updated version adds another security option. This new option is the ability to overwrite data that you have deleted so that it cannot be recovered and accessed.
When you delete files or folders, the data is not initially removed from the hard disk. Instead, the space on the disk that was occupied by the deleted data is "deallocated." After it is deallocated, the space is available for use when new data is written to the disk. Until the space is overwritten, it is possible to recover the deleted data by using a low-level disk editor or data-recovery software.
If you create files in plain text and then encrypt them, Encrypting File System (EFS) makes a backup copy of the file so that, if an error occurs during the encryption process, the data is not lost. After the encryption is complete, the backup copy is deleted. As with other deleted files, the data is not completely removed until it has been overwritten. The new version of the Cipher utility is designed to prevent unauthorized recovery of such data.
For Windows 2000 users, the new Cipher.exe tool is part of Windows 2000 Security Rollup Package 1. For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
311401The Cipher.exe utility that is included with Windows XP provides the ability to overwrite deleted data.
(http://support.microsoft.com/kb/311401/EN-US/ )Windows 2000 Security Rollup Package 1 (SRP1), January 2002
For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/298009/EN-US/ )Cipher.exe Security Tool for the Encrypting File System
(http://support.microsoft.com/kb/223316/EN-US/ )Best Practices for Encrypting File System