Gizmo's Freeware Reviews: Best Free Secure Erase Utility

12 January 2012
by admrich

Introduction

Data Recovery Risk

We've all heard the horror stories about someone buying a used hard drive at a flea market or garage sale and then finding tons of personal data left on the drive by the previous owner.

Or even worse, people getting their credit trashed by ID thieves that make their living by taking that information and using it to wipe you out financially.

"That would never happen to me," you say. "I'll delete all the files first" or "I'll re-format the drive before I trade it in or sell it." Not so fast there Scooter! That data you think you erased is still stored on the drive.

When you delete a file it isn't really removed from the disk. The file content remains on the disk until another file is written over it. Basically the same thing happens when you re-format a hard drive. Most of the data remains; the space on the drive is just made available to be written over.

Recommendations: Dealing with the Risk

To be as safe as possible, you must overwrite/erase/wipe both the slack space and free space. Also, the Windows swap file (a.k.a page file) could contain private data that you wouldn't want to have fall into the wrong hands.

For wiping the free space on large hard drives, a single pass of random data should be more than sufficient (NIST Guidelines, CMRR, Wright -- all cited for easy reference at Wikipedia).

The best policy is to wipe the free space regularly. I find almost nothing after a full free space wipe on a sizable drive. With just a single pass of random data, PC Inspector File Recovery only finds 0 byte nonsense files, or many nonsense files full of useless random data in my testing.

But on smaller drives eraser programs tend to leave behind more files of random data, and the data may be recoverable to varying degrees depending on the quality of the erasing pattern.

Since free space wiping takes so long, you may want to use file shredding in the meantime. For individual files and folders, note that the files can't "hide" as easily with an entire drive of erased random data, and some devices use wear leveling that may interfere with the effectiveness of wiping.

Erasing the Page File isn't a normal feature of eraser programs. You can easily set Windows to delete it at shutdown with a registry setting (remember to backup the registry before making changes to it). These programs set the registry for you to automatically delete it at shutdown: Ultimate Windows Tweaker, XP-AntiSpy, or Microsoft Fix It. But you can also encrypt the paging file. You can encrypt it with Ultimate Windows Tweaker, with registry or Local Group Policy changes (see Seven Forums), or from a Command Prompt:

Encrypt the Page File:
1. Start a Command Prompt, elevating it in Vista or later
2. Key in "fsutil behavior set EncryptPagingFile 1" (without quotes)
3. Restart your computer

If you need to erase a drive before getting rid of it, then Darik's Boot and Nuke (DBAN) is designed for wiping an entire drive, but be ready to spend time installing and updating windows from scratch afterward.

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