Hard disks filled with zero can be restored

Learn how to securely delete files in Windows

When you delete a file in Windows, only the reference to the file is removed from the file system table. The file is still on the hard drive until other data overwrites it, making it vulnerable to recovery.

There are many tools available to allow you to securely delete files so that they cannot be recovered. This article provides an overview of some of the free tools, many of which are portable. This allows you to securely delete files that you may temporarily store on public computers.

eraser

Eraser makes it very easy to securely erase files, folders, or both. It overwrites the files to be deleted with random data. There are several options for how often the files to be deleted are overwritten with random data, including two versions of the US standard DoD 5220.22-M (3-pass and 7-pass) and the Gutmann method of using the file with random data data is overwritten 35 times.

You can delete files and folders instantly using the on-demand user interface, or use the scheduler to schedule files and folders to be securely deleted at a specific time.

Eraser comes in a version that you can install, and you can add an option to the Windows Explorer context menu to securely delete files in Explorer. You can also download a portable version of Eraser that you can take with you on a USB stick to erase files that you have stored on other computers.

Download the installable version of Eraser from eraser.heidi.ie or the portable version from PortableApps.com.

Freeraser

Freeraser is a free, portable tool that allows you to securely delete files using drag and drop. You can choose to erase your files using a quick method that fills the space with random data in one pass, a forced method that uses the DoD 5220.22M three-pass standard, or the Ultimate or Gutmann method to delete files by overwriting them with random data 35 times. Right-clicking on Freeraser's Recycle Bin will bring up a menu where you can manually select a file to delete and change options for the program.

Download Freeraser from pendriveapps.com.

Empty and safe

Blank And Secure is another portable device drag and drop tool for securely deleting files. Simply drag and drop the files or folders to be deleted into the middle field of the "Blank And Secure" window. You can specify the number of times to overwrite the files with zeros by clicking the Overwrite X Times button and choosing an option. The deletion process can be delayed by up to 9 seconds with Delete Delay X sec. Button.

Download Blank And Secure from pendriveapps.com.

DP shredder

DP Shredder is a portable, small program that allows you to securely delete files or directories and overwrite the free space on a hard drive so that files previously deleted without using secure methods cannot be restored. You can easily select which method to delete, which includes two Department of Defense approved methods and the Gutmann method, and the frequency (rounds) with which the method is used.

Download DP Shredder from portablefreeware.com.

SDelete

SDelete is a command line utility that allows you to overwrite the free space on your hard drive so that previously deleted data cannot be recovered. It's portable and can be run from a USB stick in a command prompt window. For help using the command, type "sdelete" (without the quotation marks) at the command prompt and press Enter.

Download SDelete from technet.microsoft.com.

CCleaner

CCleaner is a program that removes unused, temporary files from your system, cleans up your internet history and cookies, includes a registry cleaning tool, and even allows you to clean up files from applications installed on your computer. The latest version offers a tool to erase the free space on your hard drive. You can erase the free space on a hard drive or the entire hard drive, thus safely erasing all data on the hard drive. There are four options for specifying how often the data is overwritten.

Download the installable version or the portable version of CCleaner from piriform.com.

A secure file deletion program is a useful addition to your software toolbox, especially if you use different computers, some of which may be public computers.