Free Hard Drive Eraser Software – Permanently Delete Files
Most computer users aren't aware of the fact that deleted files are still present on the hard drive. Emptying the trash can or recycle bin does not delete the files. The files only become marked as deleted and used disk space is freed for other data. There are many excellent undelete tools that can recover deleted files. Even disk formatting does not delete files. Especially if you have chosen quick format, all the data will still be present on the disk.
This is how computers and file systems work. Usually we don't care much about deleted files and this approach on how to delete the files is fast and convenient. This becomes a problem only when you would like to sell the hard drive or computer or when your old computer is dumped. Even if you delete all the files or even reformat the hard drive, all the files are still there! They are waiting for some curious freak or experienced hacker to recover the data for fun or for some other purpose. The problem with your old files is in the fact that they contain all the data you have created, saved or downloaded including user names, passwords, account numbers and your personal information. Such data can easily be misused for criminal purposes.
A much serious problem with old hard drives is in the governmental organizations, hi-tech companies, law firms, or any in any other company that deals with confidential data. They can not afford to simply dump old computers with all the data still present on the hard drives. Therefore, there were developed many algorithms that provide secure delete methods and solutions on how to wipe a hard drive and permanently delete files. If you completely erase a hard disk you prevent all reasonable methods of data recovery.
How To Permanently Delete Files
The basic principle is simple—simply overwrite all files with some rubbish data. This will prevent any file recovery and nobody will be able to read a single file. Nobody except highly specialized hard drive data recovery experts. Having access to state-of-the-art equipment (magnetic force microscopy) it is possible theoretically and practically recover hard drive data even if the file was overwritten. This is possible because hard drive head does not always write over the same track space. Therefore it is possible that some remains of previous writing are sill present on the sides of the track. This writing “remains” can be used to recover deleted and overwritten files. It takes a lot of money, time, expensive equipment and trained people but it is possible. And if the value of recovered data is high enough it will be done.
To solve the problem with imperfect drive tracks we can overwrite files many times and thus reducing chances of recovering old data. This is what hard drive eraser does. It uses one of popular methods to write predefined patterns of data to locations where the files in question were saved. Below you will find few free hard disk eraser utilities that will answer the “how to erase hard drive“ question.
Unfortunately, even this brute force method is not perfect. Hard drive may contain bad sectors that were once used but were later remapped because of some problem. Hard disk erasers will not touch such sectors leaving all the data on the disk. To deal with such cases there are only two methods: physical destruction of the hard drive or degaussing—using special demagnetizing devices that will demagnetize hard drive platters. If you apply these extreme methods there is probably no one able to recover the data once written to the hard drive.
Free Hard Drive Erasers
Eraser is free Windows hard drive eraser. It uses advanced algorithms to overwrite selected files: single pass, US DoD 5220.22-M (8-306 /E, C and E), Pseudo-random Data, First and Last 2kb, Schneier’s 7 Pass, and Gutmann wiping methods. Eraser is also open source—it's source code is released under GNU General Public License.
Another Windows free secure delete software. SDelete is a command line hard drive eraser that uses the Department of Defense clearing and sanitizing standard DOD 5220.22-M, which will make sure the file data is gone forever.
Darik's Boot And Nuke is a bootable disk image with hard drive eraser software that will erase all the hard drives it will detect. This is pretty convenient when you need to quickly erase all the disks before the computer is given away.
Freeraser is a freeware Windows “shredder” utility to securely erase files. It offers three methods of secure erase: a fast destruction (standard 1-round filling of random data), a forced destruction (3 rounds of filling according to DoD 5220.22M standard) and the ultimate destruction (35 rounds of filling with data according to Guttman algorithm).
OverWrite is a UNIX eraser software that overwrites files with random patterns. It's source code is released under GPL.
Wipe is a Linux hard drive eraser. It uses random pattern to overwrite files.
This is a small Windows utility to overwrite selected folders and files. It does not meet the requirements of the U.S. Department of Defence or U.K. Ministry of Defence.