Have you ever thought that what happen when you press the delete button? What actually happen behind the scene when you press the delete button over a file? You need to find the answers of these questions as it will tell you that if you have deleted file accidently then you can actually recover that, and if you can recover that then someone else surely can do the same.
What Happens When You Press Delete Button
Hard Disk Drives (HDDs)
As we all know that deleted files go to Recycle Bin, from where you can also recover the files when you are needing it again or may be have accidently deleted it. But what if you deleted file from Recycle Bin, does that means that now the file does not exist anymore? Well when you delete file, the file does not physically go anywhere, rather its index got updated which depicts that the file is in the Recycle Bin, not in any other folder.
The index is called the Master File Table (MFT) for Hard Disk Drives. See the images below, here the left most column shows the block addresses, middle column shows data in hexa code and the right column shows the actual data in plain text.
So when the file is deleted, the MFT changed and tells to the computer that that spot is now free and you can use it to write data. But until the computer overwrites data over the spot, the data (which we supposedly have deleted) remains there. Think of it like, a condemn house sitting on a lot, which is not usable but it is actually there until someone demolish it again and build something else over that spot.
You can see the problem with ordinary deletes below; as the left column shows red Xs for MFT locations which is set for overwritten while the one with the page icon is marked to stay and the right column shows data that’s still there on that location but you will not be able to see that in Windows Explorer.
Solid State Drives (SSDs)
Solid State Drives- SSDs are not like ordinary hard drives as it keep shifting files around, randomly. As the files are randomly moving so the files been deleted, its place finally will be filled with new one sooner or later.
It’s really difficult to really delete the file on old SSD, but what you can do is to get an SSD drive with TRIM capability and also make sure that your SSD data is encrypted.
It’s not really a problem for some people and they don’t look too much concerned over that there deleted information could be accessed. But if you are one of those who are little extra conscious to delete their data securely, so let’s see how you can delete securely.
What is ‘Secure’?
You can think of Security as the level of security with which you will be satisfied. If your data is not life threatening then there is no need to be overly conscious for deleting it.
Let’s see the methods in order of least secure to most secure to delete files; these methods can be applied to traditional HDDs.
Least Secure Method
You can simply delete the file and empty the Recycle Bin, as it’s the least secure method. You can delete files like silly images, GIFs etc through this method as these are not some sensitive data( as long as you think). Files deleted through this method are recoverable through data recovery software and someone can look upon the files if they want.
Mildly Secure Method (HDD Only)
You may have heard of ‘file shredders’ so what they basically do is to overwrite data on the old data so that it’s not retrievable anymore. There are many file shredders available but only being the difference of interface under the hood they are doing pretty much the same things like delete the old file, write zeros on HDD where the files were previously placed. You have to remember to manually delete the files with the shredder if you don’t want your data to sit on your drive anymore.
People who are dealing with sensitive information like tax return, bank statements etc can find these file shredders most useful.
Moderately Secure Method (HDD Only)
In this method you choose the Wipe Free Space option, means that zeroes will be written to the blocks where the files first used to be. CCleaner is usually taken as a favorite for this task. Shredders and this method differ as wiping free space takes care of ALL deleted files.
You must manually have to run CCleaner or schedule it to do the purpose otherwise it will be no good. People who delete sensitive data like online bankers, traders etc will find it really helpful as it will delete all that sensitive data that they don’t want on their computer anymore.
Most Secure Method (HDD & SSD)
These methods will come handy when you want to delete the entire contents of a drive. HDDs and SSDs are different so you must apply the method that will be appropriate for your drive and situation.
HDD – Formatting
Formatting have different meanings in different situations, it may mean simply deleting the MFT at one place or may be it means true formatting also known as low level formatting, which writes zeroes all over the data. As we already discussed your supposedly data still resides in drive until overwritten. You can’t low-level format your entire hard drive from within Windows, for this you need formatting utilities like Darik’s Boot and Nuke.
You should avoid hardcore multiple pass methods as its going to overkill your hard drive and will shorten the life span of it. The RCMP TSSIT OPS-II or DoD Short methods will be more than sufficient.
SSD – Manufacturer’s Utility
The majority of SSD manufacturers provides utility for managing and securely erasing their SSDs, which you can find from the manufacturers site or download them from here – Intel Solid State Toolbox / OCZ Toolbox / Corsair SSD Toolbox / Samsung Magician / SanDisk SSD Toolkit.
Paranoid Method (HDD and SSD)
If you want to go paranoid over the thing then you can try Disintegrate, Shred, Pulverize, Incinerate your hard drive and feel relax as with this your data will be more than safe, well un-attainable by all means for sure.
Conclusion – You got all the knowledge and now it’s up to you that what method you will choose to securely delete your hard drive data. Do let us know which method you will choose or any other problem you face while deleting a file.