When files are deleted from your computer, laptop or cellphone by emptying the Recycle Bin or Trash, or by reformatting, are you sure that the files are permanently deleted from the hard drive? The answer is No. Before you dig further, you need to understand how data is stored in the hard drive and how to securely delete files.
Data is stored in hard drive in binary forms, 0 and 1. The operating system stores the information about the location of the data in a table format. Therefore, each time you attempt to retrieve the data, the operating system refers the table for the location of the data and retrieves it.
Now, coming back to data deletion. When you delete a file or a folder of files, only the location details in the operating system table are deleted. The actual contents of the files exist on the hard disk until it is overwritten because this is the way the hard disks and operating systems are designed. Data that has not been overwritten can easily be recovered using data retrieval tools.
One of the most common ways is to erase confidential data is by formatting the hard disk drives. A person with malicious intent can retrieve the information using data recovery software.
How to securely delete files?
To ensure that you securely delete files from the hard disk, consider the following points:
Destroy the hard disk: If a hard disk is failed and cannot be used, it is better to destroy it before giving it for e-waste.
Delete files permanently: Use one of the freely available free software File Shredder software to delete files permanently. To delete entire data in a hard drive, use the free software DBAN.
Wipe the data: Microsoft provides free tool to wipe the free space in the drives called SDelete.