While there are plenty of tools available for securely wiping a disk, overwriting the data with a stream of random bits and obliterating it completely, for Windows users, there is another option: cipher.exe, a built-in Windows command line utility. While it’s not as convenient or user-friendly as the third-party tools, it’s free, it comes with the OS — and it works.
Cipher can be used to both encrypt and decrypt data , but using it with the /w switch enables you to securely erase deleted data from a directory. So, for example, if you’d like to erase the contents of a folder called “SECRET” that lives on your C: drive, you need to first ensure that you’re logged in as an administrator, then go to the command line (click Start->Run, then type “cmd”) and enter:
cipher /w C:\SECRET
Warning! Use this tool with caution — once data is erased using this method it will be irrecoverable.
(Mac users: You can do something similar using the “Secure Empty Trash” option, available through the Finder.)
What tools do you use for securely erasing your data?