Unsafe approaches of Data Disposal
We have talked about why deleted files can be recovered in previous articles.
Various data recovery software, such as H Data Recovery Software, takes advantage of the mechanism of deletion. When we delete a file, the file system only removes the address pointer to that file. But the file itself as raw data is still there. The computer just marks it as “deleted, space available”. Before new files settle in and overtake the newly freed space, data recovery software can implement their algorithms to scan and reconstruct the deleted files as they were and restore them to local drives.
The same goes to formatting. When we quick format a memory card or hard disk, the file system only clears the address table to all files. The operating system will not locate any files without their index so when you look at the hard drive you would not see any data and assume the drive is erased. In fact, the files as raw data are still there but they are no longer exist as files. They are hidden from users and will be freely overwritten, or be recovered by user or unauthorized infiltrators.
Proper Disposal of Data
As is mentioned above, data would be unlikely to recover if they are overwritten. By overwriting an old file, which is complex combinations of ones and zeros, the data patterns are re-arranged to form the new file. That is why most safe disposal methods involve overwriting.
Having a strategy for reliably erasing data files is an essential part of managing data securely and is relevant at various stages in the data cycle.
At the conclusion of a research, data files which are not to be preserved need to be disposed of securely. Unfortunately, deleting files or reformatting a hard drive will not prevent the possible recovery of data from the drive.
1. Erasing Hard Disk Drives
Erasing, also known as wiping, is a kind of overwriting. Various software is available, such as DBAN, for the secure erasing of files from hard drives. This kind of software is designed to overwrite the hard disk drives with random ones and zeros repeatedly. Its purpose is to blur the residual pattern so that even the most advanced lab-level recovery tools can only recover negligible fragments, if not none, of data from previous files.
2. Degaussing Hard Disk Drives
For hard disk drives, billions of small magnetic domains are used to store data. These domains make up the writable surface of hard disk drives with magnetized cells represent "1", while demagnetized cells represent "0".
The degaussing method uses a powerful magnetic field that demagnetizes all of the cells, neutralizing the data stored. When handling the data disposal of a large bulk of HDDs, degaussing is often preferred.
3. Resetting Solid State Drives
Solid state drives work differently from hard disk drives. SSDs read data by judging the presence or absence of electrons inside SSD flash memories. Erasing and degaussing mentioned above cannot be relied on when disposing of data on SSDs. Instead, major SSD manufacturers provide tools for resetting SSDs, which is a process of flushing out all the electrons and resetting the SSDs to the original state. This process basically writes the memories full of "1". If you cannot acquire such tools, you can read on for physical disposal.
Secure Disposal of Storage Media
Data are represented by physical substances, thus the most reliable way to dispose of data is physical destruction, that is, if these devices are no longer in your future plans.
There are so many ways you could physically destroy a storage device. You could have them shredded by certificated shredding service providers, or you could roll up your sleeves and hammer them to pieces. You could hold a trial by fire, acid or soap water, or you could drill holes all over them. If your data is extremely sensitive, drilling one hole isn't sufficient, as with some expensive lab devices and a clean room, people could read around the hole and recover other intact data from the disk. Also, when you are destroying a storage device, aim for the parts where the data are actually stored, for example, the platters in HDDs and NAND flash memories in SSDs.
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