Talvolta capita di dover eseguire il wipe dei dischi di un computer ad esempio nel caso venga dismesso, venduto o donato. Per eseguire tale operazione è possibile utilizzare vari software tra cui CBL Data Shredder un Disk Wipe Tool Free che consente di eliminare i dati da un disco mediante vari metodi:
- Custom Hard Drive Erase Method
The CBL Data Shredder program enables you to define your own method to erase a drive. The default setting is to wipe the drive once with a bit pattern of “00”. This is the simplest and quickest way to clear a drive. You may select a different bit pattern to use, and the number of times the drive should be cleared with this bit pattern. Increasing the number of passes the CBL Data Shredder program should make over the drive will increase the security of the erase process. However, it is unlikely that any custom method would be regarded as sufficient to sanitize the drive. The primary purpose is to provide a simple and fast clearing solution. For utility, options exist to write the sector number in each sector of the drive, and a custom signature at the end of each sector.
- United States Department of Defense Standard 5220.22-M
The National Industrial Security Program Operating Manual, issued to the US Army, Navy, Air Force, and other US government agencies specifies standards for the clearing, and sanitizing of data classified confidential, secret, and top secret.
Under this standard, data may be cleared by writing any bit pattern to the entire disk once. Disks are sanitized by writing a different bit pattern to the disk on each of three passes. This is how the CBL Data Shredder program implements this standard.
Drives containing top secret data are not permitted to be sanitized in this manner; they must be physically destroyed, or the disks subjected to degaussing, scrambling completely the magnetic patterns used to store data on the disk, rendering the drive itself inoperable.
- Germany BSI Verschlusssachen-IT-Richtlinien (VSITR) Standard
The German Federal Office for IT Security released the VSITR standard, which wipes the drive with seven passes. For the first 6 passes, each wipe reverses the bit pattern of previous wipe. Flipping the bits in this way is designed to destabilize the remnants of data that may exist on the edges of the track of the disk to which the data is written. The final pass amplifies this effect, overwriting the entire disk with “01010101”.
This is widely considered to be a secure method of erasing data.
- Bruce Schneier’s Algorithm
Internationally-renowned security technologist and author Bruce Schneier recommends wiping a drive seven times. The first pass overwrites the drive with the bit pattern “00”, the second with “11”, and the next five with a randomly generated bit pattern.
This has a similar effect to the VSITR standard, but the random nature of the bit patterns written in the final five passes make it very difficult for an attacker to determine how the overwriting may have affected remnants of data around the edges of the track on the disk, or at bit transitions on the disk.
Although probably a more secure method of erasing data than VSITR, the time required to create random bit patterns makes this a significantly slower method.
- Peter Gutmann’s Algorithm
Peter Gutmann, is an Honorary Researcher at the Department of Computer Science, University of Auckland, specializing in the design and analysis of cryptographic security architectures. His research into secure deletion of data from magnetic media (such as hard disk drives) is the definitive work on the subject.
The CBL Data Shredder program implements the method he devised based on his findings, erasing data with several series of passes to minimize data remnants on drives using any current techniques of encoding data on the disk.
His algorithm makes 35 overwrite passes in total, and is considered the state-of-the-art method for data destruction. The cost of this security, of course, is time; wiping a drive using Peter Gutmann’s algorithm will take more than 7 times longer than wiping the same drive with Bruce Schneier’s algorithm, and will likely be more than 15 times longer than suing the US Department of Defense’s standard.
- Royal Canadian Mounted Police DSX Method
The Royal Canadian Mounted Police Technical Security Branch makes a tool, DSX, available to departments of the Canadian government intended to prevent information disclosure when serviceable hard disk media is removed from service.
The CBL Data Shredder program emulates DSX’s method of clearing data, writing the bit pattern “00” on the first pass, “11” on the second, and a text pattern consisting of the software version number, and the data and time the erase took place.
Wiping a drive with DSX alone however is not an approved method by the Canadian government for sanitizing classified information. Current standards require the wiping of the unit with DSX standard, followed by the physical destruction of the media.
CBL Data Shredder è disponibile per Windows XP/Vista/7/8/10 inoltre esistono anche 2 packages DOS uno per creare floppy avviabile e una per creare un CD-ROM ISO avviabile.
Ho avuto modo di testare CBL la versione avviabile da CD di Data Shredder anche su computer molto datati ed ha funzionato senza problemi.