Little Description-
File table contains reference to the location of file on disk like a book’s index contains the page numbers of chapters in the book. When the file is deleted from computer recycle bin it is not fully removed from hdd only its entry in the file system table is deleted. So it is possible to recover the deleted data by using File Recovery Softwares. Wiping free hard disk space means to permanently erase the deleted file data so it is not recoverable using Recovery Softwares.
There are thousands of free space Wiping utilities out there on the internet. So if your Company Policies prohibit installing the 3rd party file wiping softwares or you are in urgent need of wiping utility and do not have access to internet you can use the in-built command in Xp/2003 called Cipher.
Cipher is mainly used for Encrypting/Decrypting the files but it also contains a “/w” switch to wipe the free space. Here’s the syntax-
Cipher /w:DrivetoWipe
e.g. Cipher /W:C
Official Description of /w Switch – “Removes data from available unused disk space on the entire volume. If this option is chosen, all other options are ignored. The directory specified can be anywhere in a local volume. If it is a mount point or points to a directory in another volume, the data on that volume will be removed.”
Cipher /w wipes the free space by writing the junk data in three steps- Writing Zeroes, Ones and Random Numbers.
Three steps wiping Screenshot-
