What is a file shredder? What can it do? Why do I need one? Which one is best? Find out with our jargon free guide!

What is a file shredder?

As we stated on the previous page, a file shredder does for files what a paper shredder does for paper, that is, destroying the file so that nobody can recover its contents. If you are thinking "Isn't that what happens when I empty the recycle bin?", then let us do a little explaining as to how files are actually deleted on your computer. Because we all like our computers to work as quickly as possible, when files are deleted from your hard drive all that actually happens is the space the file was taking up is marked as being available for reuse. This means that the computer only has to update something known on modern Windows machines as the master file table (you can think of this as a big index to everything on your disk). For most files this makes sense, but for sensitive files and folders you may wish to take extra steps to ensure your data stays private, this is where file shredders come in.

Who needs a file shredder?

One of the most common uses of file shredders is to prepare computer hard drives or memory cards for resale or disposal. If you have any sort of confidential information on your computer, or you don't want the person who buys your used memory card to recover your old holiday snaps, you should always use some sort of file shredding utility to clear off all the data before you consider selling or disposing of it. Programs which securely wipe an entire computer or hard drive are sometimes known as "Disk Sanitisers" or "Disk Purgers". If you cannot use one of these utilities on your old hard drive (perhaps because it no longer works) punching a couple of large nails through the hard disk unit will usually suffice.

Users are often suprised at the amount of deleted files that IT experts can recover.

Of course, that isn't the only reason to use file shredding utilities. Many users like to use the facilities offered in some of these programs to clear web surfing history, particularly on shared computers. They can also be used in conjunction with encryption programs to make sure that no remnants of important data remain unencrypted on your computer. Most modern file shredders can also securely erase free space on your hard drive, meaning that even files you (insecurely) deleted in the past should now be securely erased. Shredding cannot, however, protect you if you download illegal or copyrighted material from the internet, since, although you can erase the tracks left on your PC, access logs will still exist with your ISP (internet service provider). It is up to you to decide if you need a file shredder based on the kinds of information you store on your PC.

Are all file shredders the same?

There are many file shredders on the market today, many with advanced features and options that can cover almost every eventuality. However, securely deleting files on modern computers is not as straight forward as you might imagine. Many of the market leading file shredding utilities leave behind remnants of information, struggle to remove smaller files or can corrupt larger files. While we haven't tested the effectiveness of our recommended products at a forensic level, we conducted extensive research using the web and IT journals to determine the thoroughness of the shredding engines in our two chosen packages.

Does using a file shredder guarantee my privacy?

Unfortunately, due to the complex nature of modern operating systems like Windows, there are no 100% guarantees. Data that has been securely wiped by a good shredding utility will be impossible to recover using regular software. If your adversaries are willing to pay large amounts of money, it might be theoretically possible (but potentially very difficult) to recover data by inspecting a hard drive in a forensic data laboratory. Finally, even the top rated file shredders have been shown to leave some remnants of files behind in some circumstances (some brands of USB hard drive seem particularly difficult to clean, even with Evidence Eliminator). If your data is particularly sensitive or prone to theft (such as data on a laptop), consider using encryption software to keep your data secure. We cover encryption software in our guide to encryption tools.

What file shredders are available?

At Top-Windows-Tutorials.com we tried several different packages before deciding on two to recommend to you. The two products we chose were Eraser and Evidence Eliminator.

Eraser

Eraser is a free file shredder and privacy protection tool that has won several awards including "best file shredder award" in Chip online magazine. Eraser has a plain looking interface but actually includes quite a few neat tricks and of course, being free, it is excellent value for money. Files or folders can be securely erased (or securely moved) by right clicking on them. A complete clean of your computer including free space on your hard drive can be scheduled using the programs built in scheduler. Security wise, Eraser can use anything from a simple one-pass wipe to the highest security Gutmann file shredder routine. Eraser also comes equipped with a "Create Nuke Boot Disk" option which can create a bootable CD-ROM disk that can securely wipe the entire contents of your computer before you sell or dispose of it, very handy indeed.

Although it lacks some of the more advanced features that Evidence Eliminator boasts, Eraser is a solid package that will suit the needs of many users and being free, its price won't hurt anyone's wallet. You can download Eraser by visiting the Eraser homepage.

Evidence Eliminator

Evidence Eliminator is a commercial package that has been around for some years now. In most round-ups of file shredders, Evidence Eliminator usually comes out top. In the August 2006/Vol 49 No. 8 issue of Communications of the ACM (Association for Computing Machinery), Hal Berghel and David Hoelzer tested several file shredding utilities and said that Evidence Eliminator was the only product that "eliminated enough of the data to fall within our comfort zone." This test was carried out using flash media (memory cards) and the software comfortably outperformed its competitiors and was the only product to leave behind no discernable data residue.

The programs feature list is extensive and it includes plug-ins that can clean private data that popular Windows applications leave behind in the registry and on disk. New plug-ins are developed all the time and expert users can even develop their own. As with Eraser, files or folders can be securely wiped by right clicking on them, although the secure move option is missing (you can still securely move files by copying the file and then securely deleting the original). Windows Vista and Windows 7 users please note- With version 6.03, the option to securely wipe files by right clicking on them is now available when Evidence Eliminator is used with 64 bit versions of Windows. However, we have discovered that this feature does not work if you are running a limited user account.

Unlike Eraser there is no scheduler built into the program. Instead, the software can replace the standard Windows shut-down with Evidence Eliminators "safe shut down". The idea being that Windows starts to shut down and closes all other programs so that Evidence Eliminator can work without the risk of another program interfering with it or writing data on freshly cleaned areas of your hard drive. This approach does provide the best security, however a high security clean of a computer with a large hard drive takes a long time (possibly more than 24 hours in extreme cases). Because of this we cannot help but think that the schedule method Eraser uses is possibly a better approach for some users, in spite of the extra risks.

We were a little disappointed that there was no 'disk sanitiser' included with the package. Although as Eraser is free, there is no reason why EE users can't use the "Nuke Boot Disk" included with that package. There is also no Gutmann very high security file shredding routine although you can increase the number of repetitions the shredding engine takes to as many as you like. There are even facilities in the program which claim to defeat inspection by electron microscopes used in forensic laboratories, though we were unable to find any examples of this being put to the test.

With full support for Windows Vista, free and prompt e-mail technical support, a proven track record and the richest feature set in the business, there is little doubt Evidence Eliminator is the best file shredder available. Whether that warrants the $149.95 asking price is for you to decide. Our only minor gripe is that the marketing that has been used to sell the product has, in our opinion, been a little over-heavy on the scare tactics. Although the company seems to have cleaned up its homepage a little now, in days gone by it used silly scare tactics such as printing your ISP details (something that is very easy to do) and declaring "You are under serious risk of investigation". If that were true, then no disk cleaning utility would save you, since your ISP keeps records of your activities anyway. While the Evidence Eliminator home page seems to neglect this fact, please don't let that put you off if you require the most powerful file shredder on the market.

You can find out more about Evidence Eliminator pricing and features by visiting the Evidence Eliminator Homepage. We've even negotiated a 10% discount for visitors to Top-Windows-Tutorials.com! Alternatively, you can download a trial version by clicking here. Although the trial version of the software is heavily crippled and won't actually do any file shredding, it can still give you an idea of how the software works.

Reckon you can clean your own hard disk?

Deleting "Internet Cache and History" will NOT protect you. Formatting a disk may not destroy the contents. Pressing Delete does NOT destroy files.

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