Data encryption is really important especially if we have sensitive files that cannot fall into other people’s hands. We can use one of the most best yet free encryption software called TrueCrypt to encrypt our data but then if you think carefully about it, there is actually a time frame when the files are not yet protected and are stored as normal files on your hard drive. Even after moving the files to an encrypted container or simply deleting them from your computer, there is a possibility that the files can actually be recovered using a simple to use free data recovery software if they are not being overwritten.
There are some dedicated tools to permanently wipe or shred the files to prevent from being recovered. However if you’ve removed the files using the standard Windows delete command and emptied the Recycle Bin, Windows does not offer a way to restore it back unless you use a recovery software to restore the file, and then use the file wiping software to permanently delete it. Overtime, the amount of accumulated recoverable files on your computer can be quite shocking. A good way around this is to use some free utilities that is able to make the recoverable files unrecoverable without touching your existing files.
If you do a research on data wiping, you may find that there are many different file erasure methods such as Gutmann, DoD, Schneier and etc. Eraser is one of such tool that supports different types of wiping algorithms including Gutmann for the paranoids which is selected by default. To permanently wipe the empty space on your hard drive using Eraser, run the program, right click at the Erase Schedule box and select New Task. Click the Add Data button, select the “Unused disk space” radio button and click OK. Click OK again at the Task Properties window to close it. A new task is added to the program, to run it simply right click and select “Run Now”.
Do take note that the Gutmann method would take a very long time to complete because it writes a series of 35 patterns on the empty space. If you have a large hard drive with a lot of empty space, the whole process can easily take the whole day to complete. Another drawback is Eraser does not show an estimated remaining time other than the status bar. You can always cancel the task by right click and select Cancel Task from the context menu.
2. Moo0 Anti-Recovery
Moo0 Anti-Recovery is a free and very easy to use program that fights the recovery tool by writing the empty spaces once with pseudo-random data. First you need to select the drive that you want to process and then followed by checking a few options such as recycle bin, free space, MFT, cluster tips and even file names.
There are no other choices in the wiping techniques other than the built-in method which is good enough to prevent from recovery programs used by end users.
BleachBit is a famous free utility that is meant to clean out junk files from your computer to free up more space on your hard drive and protecting your privacy at the same time. There are 2 ways to wipe the free space using BleachBit. First is to click the File menubar, select “Wipe Free Space” and choose a folder or drive that you want to wipe. Second method is to check the “Free disk space” from the System category and click the Clean icon. There is no option to cancel the process but you can terminate it by closing the program. It also shows an estimation of time remaining to complete wiping.
BleachBit wipes the space using a single pass of blank data which they think is sufficient and the additional passes adds no value other than slowing down the whole process. BleachBit can be ran on Windows and Linux.
CCleaner, probably the most famous Windows optimization and cleaning utility around today offers a tool called Drive Wiper to securely erase the free space on your hard drive. Run CCleaner, go to Tools > Drive Wiper, select “Free Space Only” for wipe, then the overwrite method and finally the drive that you want to wipe.
CCleaner has 4 wiping techniques which is 1 pass, 3 passes (DoD), 7 passes (NSA) and 35 passes (Gutmann). The more passes that you select, the lower in chances of recovery and longer it will take to wipe.
SlimCleaner is a well known and fast growing computer maintenance software that comes with a lot of features to keep your computer clean and optimized. To access the disk wiping tool, run SlimCleaner, click on Disk Tools and select Disk Wiper.
Similar to CCleaner, it also 4 wiping methods which is 1, 3, 7 and 35 passes. Make sure that “free space only; your data will be safe” option is selected and followed by clicking the drive to process and finally click the Wipe button.
6. File Shredder
File Shredder, as its name suggests, it is a free tool meant for shredding single and multiple files including free disk space with Windows shell right click integration. To wipe the free disk space, run File Shredder and click on “Shred Free Disk Space” at the left pane. A new window will open where you can select the disk to wipe and the secure algorithm to use. Click the Next button and then Start.
File Shredder supports 5 types of algorithm which is 1, 2, DoD, 7 and Gutmann 35 passes. The simple two pass option that is not available on most other tools would be a fine choice if you want a good balance between time and speed.
7. Disk Redactor
Disk Redactor is another simple utility that wipes away deleted files. There is an option button where you can enable erase information twice, run a check disk, working in background and writes with random data instead of just filling it with zeros but it’s not available for free users. To start the secure delete, click on the Wipe Disk button and select the drive or folder. During testing we found that selecting any folders on the drive will wipe the drive’s empty space rather than the folder.
Although not mentioned anywhere, we strongly believe that Disk Redactor uses 1 pass because the licensed version can enable 2 passes option. Logically this means that the free version should be using a less secure algorithm compared to the paid version.
The built-in cipher.exe tool in Windows operating system located at C:\Windows\System32\ is actually a file encryption utility that can be used to remove data from available unused disk space. Simply type the command below and followed by the path to the directory or even the root of the drive letter.
Cipher.exe uses 3 passes algorithm where it overwrites the specified unused free space with all zeros, all ones and finally random numbers. The advantage in using the cipher.exe tool is the availability on Windows operating system since 2000 plus you can run from it an un-elevated normal command prompt.
Important Note: There is no need to continually wiping the free disk space on your computer because it will only increase the wear and tear of the drive and reduce its lifespan especially on SSD drives. What you can do is, wipe the unused free disk space once using any of the software listed above depending on your requirements on the algorithm, then start managing sensitive data in an encrypted container created by TrueCrypt or any other reliable encryption software.