Deleting Files Securely
Why isn't deleting a file enough?
Many believe that when a file is deleted, it is permanently erased. In actuality, the data within the file still remains on the drive; this is because of how the Windows operating system saves and deletes files.
- When you save a file, the PC stores the file name in a file allocation table. The data that actually makes up the file is saved directly on the computer's drive.
- When you delete a file, the computer removes the file reference from the file allocation table, but the data still remains on the drive. The space occupied by that data is marked as free space and is available for overwriting by other newly saved files. But until another file's data is saved over it, the deleted data remains.
Note: Formatting a drive does not erase data. Formatting erases file allocation information and performs other housekeeping functions for data storage, but formatting does not erase data.
Even though you can't see the deleted file, someone using easily available software tools can recover the file and view its contents. This poses a significant security risk and can lead to confidential information falling into the wrong hands. To securely erase files so that they can never be recovered, a data wiping tool should be used.
Secure data wiping
Data wiping tools erase data by overwriting it with random characters. Each overwrite pass causes the data that previously occupied the location to become less "bright" than the random data that now rests on top of it. As you increase the number of overwrite passes, the greater the security.
Most data recovery software products recognize only the brightest, topmost layer, so one overwrite pass is usually sufficient. However, more advanced hardware extraction methods, such as an electron microscope, can often read up to seven layers down. This is why the U.S. Department of Defense standard is seven overwrite passes.
iolo's DriveScrubber gives you the flexibility of tailoring the patterns used in the overwrite passes and lets you select the number of passes—you can choose the Department of Defense standard of seven overwrite passes or, for the utmost in security, overwrite data up to 100 times. DriveScrubber is a part of System Mechanic Professional, which also includes PC tune-up, data recovery and internet security in one package.
Unlike other data wiping software, DriveScrubber offers dual protection for permanent data removal: you can completely wipe all the contents from a drive or device, or you can erase just the remnants of previously deleted files. Both options meet or exceed the standards of the U.S. Department of Defense.
- DriveScrubber can wipe the entire drive to completely erase all data. People find this useful if they want a "like new" drive after virus damage.
- DriveScrubber can wipe only the free space to thoroughly erase the remnants and tracks left by deleted files. Existing files, programs and the operating system are all left in intact. People find this useful for regular computer maintenance or for wiping private data prior to a computer donation.