Let’s discuss trash for a moment. A by-product of human existence, our trash never really goes away. Sure, some of it might biodegrade into the soil, but most of it, unfortunately, just hangs out. Your digital refuse isn’t much different – the files and folders you “delete” or toss in the Recycle Bin don’t actually disappear from your computer, just like the old newspaper you throw in the garbage doesn’t disappear from the planet.
The only difference between your physical trash and your digital trash is in what’s being thrown away. Think about it: most people are not going to be interested in tracking down and retrieving an empty jar of peanut butter or burnt-out light bulb, but those old excel documents of financial information that you “deleted” from your computer before throwing it away or selling it might have a bit more appeal.
Fortunately, there is software available to address this problem. Programs like Laplink SafeErase serve to securely delete whatever data you choose from hard drives, ensuring that your digital trash is protected from those who would pick through it. But what is it that these kinds of programs do that you can’t do yourself? Why is a piece of software like SafeErase so critical to wiping files off of your computer? Well, we’re glad you asked.
The Recycle Bin
From unflattering photos to old resumes, your computer’s recycle (or trash) bin has seen quite a bit. Unfortunately, sending a file to and then emptying your recycle bin doesn’t actually remove the data from your hard drive. According to the Wikipedia page on data remanence, “The delete function in most operating systems simply marks the space occupied by the file as reusable without immediately removing any of its contents.” The data is then still recoverable until the computer rewrites it with a new file (like another unflattering photo).
As long as your computer rewrites every file you delete, your information is safely deleted. However, your computer doesn’t have the threat of identity theft in mind when choosing which space to store a new file. There is no way to be certain that “deleted” files containing private information actually are deleted, which is where deletion software comes in.
Unless you want to resort to the fairly extreme (albeit cool) measures of drive slagging, a data deletion program will be your best bet for securely cleaning old or unwanted data off your hard drive. Because we love talking about our products and never pass up an opportunity for self-promotion, we’ll use Laplink SafeErase as an example.
Highest security method: 35 Cycles
Based on a process developed by New Zealand computer scientist Peter Gutmann, this method overwrites data with a series of 35 different deletion cycles, executed in random order.
High security method: 7 Cycles
This method is based on the January 1995 “National Industrial Security Program Operating Manual” published by the U.S. Department of Defense. The seven cycles consists of three overwrites with the DoD 5220.22-M (E) Standard, a random value overwrite and then three more DOD 5220.22-M (E) overwrites.
Medium security method: 6 Cycles
As described in the “BSI IT Baseline Protection Manual” by the German Department of Security in Information Technology, this method overwrites data with a random value and then with its value compliment. The procedure is completed with three additional random value overwrites.
Low security method: 3 Cycles
While it offers a lower amount of security, this method is much faster than higher security methods. Based on the “National Industrial Security Program Operating Manual” (NISPOM) of the DoD, the data are overwritten first with a set value, then its compliment and finally with a random value.
Lowest security method: 1 Cycle
Even faster than the three-cycle method, this method overwrites data with a single random value.
Overwrite with Zeros
This is the fast method of secure data deletion. The selected data are overwritten with zeros to delete them completely.
And what makes the 35-cycle method more secure than just overwriting everything with zeros? For the answer to that question we turn to Laplink CTO extraordinaire Jack Wilson:
“The level of erasing will depend upon the level of concern of the person wiping the disk,” he said. “A simple overwrite of zeros is generally good enough so the files cannot be restored with typical retrieval programs. However this might not meet external requirements for sanitizing a hard drive as defined by HIPPA or DoD requirements. The more extreme methods allow the hard drive to be sanitized to the point that even extensive laboratory analysis, such as Magnetic Force Microscopy, will not allow data to be recovered.”
If this seems a bit complicated, think of it this way – your hard drive is like film on a videotape (a bit archaic, but we all still remember VHS, don’t we?) and your data is like the recorded images on the film. As many home-movie enthusiasts probably know, recording something new on top of what’s already on a videotape covers up the original footage, irretrievably. When Laplink SafeErase or other data deletion programs overwrite selected data on your hard drive, it produces the same result – the original information becomes inaccessible and securely deleted. The more times you record/rewrite over something, the more buried it becomes.
Makes the recycle bin on your desktop seem pretty irrelevant doesn’t it? At least now you have a better understanding of what all is involved in the secure deletion of data, and know where to turn when the time comes for you to make sure that those important super-secret files are properly destroyed.
Speaking of which, if you haven’t yet found the right product for securely deleting your data, why don’t you take a look at Laplink SafeErase. Did we mention that it features six different deletion methods?