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Technology Exploration Project – M591

How much will you pay for 'safe' and 'permanent' deletion?


The Contenders


When you delete a file from your windows system, where does it go? You might answer me "To the recycle bin, until I empty the contents!", and while this is true to an extent, this is not the end of the line for those unwanted files. When a file is moved to your recycle bin and you empty the bin, the file itself never moves location. It is still stored in the same spot on the storage medium but its path is renamed and re-indexed and placed in a hidden folder on the storage medium named recycled. Further to that, to add even more doubt to the security of your deleted files, Microsoft added a file indexing the original name and path stored in a hidden index file called info2 located in the recycled folder. So, if you delete the index file and the hidden file in the recycled folder you may think that this truly is the end of the line. We're close, but that file still exists in memory. When you delete the file from the recycled folder, Windows doesn't remove the file from memory, it changes a flag on the storage medium that indicates that a file exists there. All of the bits storing the information about the file still exist in the memory (What happens to a file once you hit delete, 2007). There has been an ongoing debate as to what methods best suit the purpose of securely deleting data, and the two products I am about to investigate address several of these issues.

The two pieces of software are from different producers and one is open source, the other is a package of products that require payment to use the features after 15 days. The open source product is named Eraser, and is produced by Heidi Computers Inc. It provides secure file removal be removing the data from the operating system's file lookup and cache, and then overwriting the data on the storage medium several times with specially selected patterns. It also offers a facility to allow you to generate your own overwriting methods, using things such as random number generators, pre-defined encryption algorithms or methods defined in the National Industrial Security Program Operating Manual of the US Department of Defense. The second piece of software is a data security suite, known as Data Security Wizard, from a company named Easeus and it costs the user $19.95, a trivial amount for peace of mind. Data Security Wizard is an encryption program that encrypts personal files and data sensitive to attack. It is designed specifically for Windows systems and uses within their software a self proclaimed "best wipe algorithm for wiping your data" (Data Security Wizard, n.d.). I will install and test both of these products on my personal machine, and analyse and state the problems, benefits or issues that I find, as well as discussing some of the theory behind their operation. I will also ask a child of fifteen to try to install and use the program, and an adult of forty five.

From this article you will see that, in my opinion, paying big bucks is not always the way to go for safer data.

Testing the Applications


The first thing to notice with the installation is that the Data Security Wizard requires a system reboot to become functional. When compared to Eraser, which does not require a restart, this could be considered an unnecessary inconvenience. Also, upon rebooting after installing Data Security Wizard, I encountered the infamous "Blue Screen of Death", familiar with windows users for problems such as corrupted memory, registry entries and faulty device drivers. I'm taking an educated guess that the former is the culprit for this screen. Not a good sign, however after subsequent restarts I have not been able to replicate this problem. When installed by the younger and older testers the problem did not surface again, so it may have been a one off occurrence, but is still a worrying problem. When deleting a file with Eraser, it offers the user several options as to what type of algorithm to use to securely delete the data, each offering a different number of passes over the data and a different type of data to overwrite it with:

Eraser Options


Using a 4MB block of data the longest deletion time was the Gutmann algorithm, which took 17 seconds to erase, and the fastest was the first and last 2 Kb method, which only took 0.05 seconds to erase. This obviously leads to the question of which is most secure, and it is quite easy to tell, the first and last 2 Kb method only overwrites the first and last 2 Kb of data, and therefore is nowhere near as effective as the Gutmann method, which overwrites the whole data 35 times. In the case of the fifteen year old, the options part of the erasing was overlooked and not even opened. The forty five year old also did not look into the options and did not question which would be most secure. Unless you are technically aware, or are worried about the data you are trying to protect, this is pretty much a non-issue for most users, as long as their data is deleted.

Carrying out the same tests on the same 4MB block of data with the Data Security Wizard, the offer of algorithm options is not available to you explicitly. If you right click on the file and select wipe:

DSW Options


It just deletes and wipes the file, taking 1 second for the 4MB block of data used in the previous examples. However, when you enter the program and go through the process of deleting the file using the wizard, you get offered three different options:

DSW Wizard Options


To the fifteen and forty five year olds, this was not accessible, as they both went straight to the wipe option from the right click menu, and did not even bother to look through the wizard itself and see what kind of security it could offer.

Comparing the Products


Both products offer the same functionality, the safe and permanent deletion of data from your storage medium. The extent to which they offer it differs though. With Eraser, there are several features that are not offered by the Data Security Wizard, the most prominent of which is the fact that it explicitly offers the user the choice of which wiping algorithm to use, and even specify their own algorithm to customise the operation even more. Another feature offered by Eraser is that it offers scheduled medium wipes. So, for example, if you were storing sensitive information that changed daily, you could securely wipe the data in the specified folder or drive at, for example, 5am every morning, ready for a new set of information that exists for that day. Data Security Wizard offers other functions that are not provided by Eraser. It offers the user the ability to create an account with which all wipes, encryption and decryption are associated with, and requires a password to activate each of these activities. It also offers encryption and decryption of selected data, so you can protect sensitive data that is required to be kept rather than permanently deleting the data.

The two products both offer support in the form of an F.A.Q. section. Eraser has a fully moderated and supported forum with significant input from users and developers pointing users in the direction of solutions and keeping them informed on incoming updates. Data Security Wizard however, offers an online help form which allows the user to read through a manual about the product. It seems that the money you pay for Data Security Wizard doesn't buy you much more, if any more at all, than Eraser, which is supported by a large community.

For the deletion of data, the similarities lie solely on the wiping algorithms used by the programs. They both use the US Department of Defense Method as one of their wiping algorithms, and they also both use some form of pseudo-random number generator to cover the data. Eraser uses the ISAAC cryptographic number generator (ISAAC, a fast cryptographic random number generator, n.d.), whereas Data Security Wizard uses an undisclosed form of number generator. Eraser also offers the user a sophisticated algorithm developed by a man named Peter Gutmann, which passes the data a large number of times with a set of information generated by the algorithm. This reduces the possibility of highly sophisticated hardware that can detect the magnetic differences on the medium and detect where data was once stored and what form it was in (Secure Deletion of Data from Magnetic and Solid-State Memory, July 1996).

The weaknesses of each system are that each one uses a publicly known set of algorithms to hide the data. This means that given sophisticated enough technology and software, it may well be possible to recover the data, but for personal use this isn't as much of an issue. Eraser provides more security against this if the user opts to use the Gutmann method which overwrites the data several times making the magnetic signatures left become weaker with each pass. In my opinion this makes Eraser a slightly more effective product for use with magnetic storage, however this effect is not nearly as useful in storage such as DRAM and flash devices (Secure Deletion of Data from Magnetic and Solid-State Memory, July 1996).

Where to use them


There are different scenarios and situations where each product would be more beneficial. In situations such as, for example, a fictional bank has several vaults and each one has a unique pass-code that is changed every hour and these pass-codes are stored on a magnetic device, Eraser would be my product of choice. I would choose Eraser for the fact that it allows the user to schedule wipes of selected drives, folders and files, and the time interval is entirely at the user's discretion. Also, for the reason that it is stored on a magnetic device, I would use Eraser with the Gutmann method selected to minimalise the possibility of magnetic variance readings. However, in an scenario where a company wishes to keep data on its customers and they wish for it to be encrypted, Data Security Wizard would be my product of choice and the cost for this feature is minimal. The password protection feature of the encryption and decryption functionality of Data Security Wizard enable the user to specify a password to encrypt or decrypt the data for extra security.

For home use, I would recommend Eraser since it is a free product and the added benefits of encryption that you would gain from Data Security Wizard are not necessarily useful in a home situation.

Conclusion


Perception is a deceiving thing, many people believe that the more you pay for a product, the better the service it offers is. This is not always true. From this simple comparison of two products, it has emerged that the free option is, in my opinion, a superior product, and that the only feature you are paying extra for with Data Security Wizard is the encryption part of the suite. The support offered for each product is similar, and fairly comprehensive, they are both easy to acquire, install and maintain. Eraser is slightly easier to use from my point of view, and the scheduled erase option is an extremely useful one depending on your situation.

Why pay more for a product that you can get for free? The answer to this is simple, you shouldn't.

References


Page revised 2008-06-15 09:20 • ©2012 University of Portsmouth • This website uses wikkawiki.org software.