Wiping Disks using Windows Cipher

Before disposing of hard disk drives, I wipe them to remove all personal information. There are many utilities available for this purpose, such as the "cipher" program available on Windows XP and above.

The Windows cipher utility overwrites "available unused disk space" so that it cannot be recovered later. In other words, it wipes deleted files form a disk, leaving normal files unchanged. To delete a disk completely, quick-format it before using cipher. Read the Microsoft knowledgebase article describing the tool.

Using a dos shell, an example command to wipe a disk or partition is:

cipher /w:drive:\directory

where 'drive:\directory' is the drive you want wiped, such as "cipher /w:Z:\" for the entire Z drive.

Microsoft Gotchas

During my testing under Windows 7 the colon must be present to wipe an entire drive. Running cipher without the colon will not wipe a drive. Cipher will not report an error or warning. It will appear to be working, just not wiping the drive.

For example, this command will not wipe drive E, even though cipher appears to be working:

Here is the correct syntax to wipe drive E. Note the final colon.

Confirm that cipher is working by checking for a hidden directory and file on the drive. Cipher works by expanding this temporary file until the drive is full.