Secure Delete versus Delete – What’s the difference?

There’s an important difference between the technical terms “delete” and “secure delete”.

The technical computer term “delete” refers to the type of computer function where the data is marked as deleted, but not really gone. Functions such as dragging a file to the trash/recycle bin and then emptying it marks the data as deleted so the space can be used again, but the data itself remains on the hard drive and recoverable until it is overwritten by something else. On a hard drive with lots of free space, this could take months or even years.

On the other hand, the technical term “secure delete” refers to the type of computer function where the data is overwritten by other characters so the data can’t be recovered. “Secure Delete” is also referred to as “clean”, “wipe”, “erase” and “shred”. Computer software that performs this type of function is often called a “file shredder” a “data shredder” or “secure delete utility”. For more information, see Wikipedia, “Data erasure

The important difference will be evident to you if something like this has happened to you:

  • You’ve moved confidential files to the recycle bin and emptied the recycle bin. Now you realize they’re still on the hard drive, but you can’t get to them
  • You’ve used the delete function in your email program to delete email, that email is no longer in the email trash and you want to erase the email instead, so it can’t be recovered
  • You’ve used a “clear cache”, “erase history”, “clear history” or “clear private data” function in your web browser and you now want to erase your cache or history instead
  • Your browser has already deleted your internet cache, internet history or other internet tracks and you would like to erase them instead
  • Your computer is pre-owned and you want to ensure there’s no objectionable material (like porn) still on it from the previous owner

In each of these cases, your computer has moved the confidential files to the disk free space. Disk free space is the area on your hard drive containing de-allocated memory, which is where all the data you have previously deleted is stored, until it is overwritten by something else or until you secure delete your free space. In the meantime, the data can be recovered by someone with a little know-how and access to your computer.

Is this a design flaw?

When the first personal computer with a hard drive in it came on the market in the 1980s, this wasn’t an issue. Remember that deleted data is stored in the free space until it is overwritten by something else.  Since the first hard drive only had 10K of memory on it, there would be only a short period of time before that free space would be overwritten by something else. More importantly, secure deleting everything instead of just deleting adds tremendous overhead to the system – a system that was already struggling to keep up with the demands put on it. (In the 1980s, it wasn’t uncommon for saving a document to take 5 minutes.) So why is it that with modern operating system, your computer still doesn’t handle this for you – secure delete each file as you put it in the trash? The answer is still the same – speed. Secure Deleting everything instead of just deleting it would slow you down enough that you’d get really annoyed and would wish the operating system wasn’t designed that way.

You have Choices

Instead, you have choices. Some Operating Systems give you Secure Delete options. But many people use a secure delete App, like our File Shredder, ShredIt, which has been on the market the 1990s. Secure Delete Apps offer other features like government secure delete standards compliance, multiple overwrites and step-by-step documentation. There are also free options available, some with more features than others. Whichever option you chose, make sure you can understand the directions before proceeding. Once something has been secure deleted, the contents really can’t be recovered.