Data wiping or sanitization helps users in avoiding data spillage, data breach and securely handling confidential files. Various data erasing programs allow multiple overwrites so that they can be more tightly secured to be used in government and industry standards where high security is required.

A standard data sanitization or wiping software will always provide verification of data removal which is compulsory for fulfilling certain standards. There are various data wiping methods listed below which are differentiable via their logic and the number of passes it uses to overwrite the data. Also, it helps in data mitigation and protects temporary data.

It is also known as data wipe methods, data wipe standards, data erasure methods, and wipe algorithms. Let’s have a look at these data shredding methods to understand the process and importance of their execution.

Data Sanitization – Methods that Guarantee strong Data security

Data Sanitization methods can be used for various personal and professional purposes. From a single user to a vast organization, anyone can use these methods to maintain the confidentiality of their respective documents.

1. The Random Data method

data sanitization

The Random Data method is one of the most popular and constantly used data wiping methods for overwriting data on a storage device or a hard drive. This method uses only random characters to overwrite and is implemented in the following manner:

  • Pass 1 – ?: Writes a random character

You can customize the number of passes, so the method can be executed in as little as  2 passes or as long as 20 or 30 passes. You have the option of verification either after each pass or only for the final pass. The more the number of passes the better data destruction takes place.

Supported programs: DBAN, Eraser, Disk Wipe, Freeraser, WipeFile, Secure Eraser

2. The Write Zero Method

The Write Zero Method is one of the most popular and constantly used data sanitization methods used for file shredding and data destruction. It does restrict retrieval of data through software but if advanced hardware methods are used, some of the data can still be recovered.

The Write Zero Method can also be called a Single Overwrite method, Zero Fill, or Zero Fill Erase. It works in the following way:

  • Pass 1: Writes a Zero

You may get verification or may not sometimes. It all depends upon the software you are implementing the method. You can also customize the method.

Supported programs:  DBAN, HDShredder, KillDisk, Macrorit Disk Partition Wiper.

3. Secure Erase

Secure Erase is a set of commands that are found from the firmware on PATA and SATA based hard drives. This data wiping method uses the Secure Erase commands to overwrite the data on the hard drive. Security Erase Unit and Security Erase Prepare are two of the Secure Erase commands.

Basically, once the file is deleted using Secure Erase commands, no data recovery method will be able to recover the original data.

Secure Erase works in the following way:

  • Pass 1: Writes a Zero

It has a single pass. The pass 1 writes a binary zero or one. Overwriting does not need any verification because the writing is done inside the drive, which makes Secure Erase very quick and effective.

Supported programs:  MHDD, CopyWipe

4. DoD 5220.22-M (US Department of Defense)

DoD 5220.22-M is one of the data erasure/wiping methods used for shredding files permanently from your hard drive or any other storage device. Using DoD 5220.22-M as your data sanitization method will prevent all the recovery methods to extract the deleted files. This method was founded by the US Industrial Security Program (NISP) in the National Industrial Security Program Operating Manual (NISPOM).

The method has three passes and gets implemented in the following way:

  • Pass 1: Overwrites all addressable locations with binary zeroes
  • Pass 2: Overwrites all addressable locations with binary ones (complement of Pass 1)
  • Pass 3: Overwrites all addressable locations with random bit numbers
  • Verify the final overwrite pass.

The aforementioned method was tweaked following the 2001 update, in which the DoD pattern added more steps to the DoD-3 pattern. Then, in 2007, the DoD-3 became DoD-7 pass.

  • Pass 1: Overwrites all addressable locations with binary zeroes.
  • Pass 2: Overwrites all addressable locations with binary ones (the complement of the above).
  • Pass 3: Overwrites all addressable locations with a random bit pattern.
  • Verify the full drive.
  • Pass 4: Overwrites all addressable locations with binary zeroes.
  • Pass 5: Overwrites all addressable locations with binary zeroes.
  • Pass 6: Overwrites all addressable locations with binary ones (the complement of the above).
  • Pass 7: Overwrites all addressable locations with a random bit pattern.
  • Verify the final overwrite pass.

Supported programs:  DBAN, CBL Data Shredder, Eraser, Security File Shredder, Freeraser

5. NCSC-TG-025 (US National Security Agency)

NCSC-TG-025 is one of the data sanitization methods used for shredding sensitive data so that it cannot be recovered. You can delete data if it is on the hard drive or any other storage device. Using NCSC-TG-025 as an erasing method will disallow all the recovery methods to extract the data deleted by any option.

NCSC-TG-025 passes over the data at least once to overwrite it with a zero, one, or random character, unlike other methods like Write Zero which overwrites the information with zero or Random Data which uses random characters.

It uses three passes. NCSC-TG-025 works in the following manner:

  • Pass 1: Writes a zero and verifies the write
  • Pass 2: Writes a one and verifies the write
  • Pass 3: Writes a random character and verifies the write

This method verifies that the data was successfully overwritten before going to the next pass. If the overwriting of the data fails then it will do the specific pass again until it gets successfully overwritten. If it is not able to complete that pass, the software will ask the user to return to the pass manually.

However, if you change anything in the above method, it cannot be labeled as the NCSC-TG-025 method.

Supporting programs: WinUtilities, Disk Shredder

6. AFSSI-5020 (US Air Force)

AFSSI-5020 is a data sanitization method used to remove files and folders from your hard disk or any other storage device permanently by overwriting the existing information so that it cannot be recovered by any of the recovery programs.

By erasing your data with AFSSI-5020 data sanitization, you will prevent all the recovery software/hardware to extract the deleted file. AFSSI-5020 data sanitization method uses zeroes, ones, and random characters in a specific order and number of passes. It has three passes and works in the following flow:

  • Pass 1: Writes a zero
  • Pass 2: Writes a one
  • Pass 3: Writes a random character and verify the writing process again

The AFSSI-5020 will lose its originality and integrity if you decide to make changes in the number of passes or the types of writes in the program. For example, if you fill the first three passes with random characters and add several more passes, that becomes the Gutmann method code.

Supporting programs: Eraser, Hard Disk Scrubber, PrivaZer

7. AR 380-19 (US Army)

AR 380-19 is a data sanitization method used in data destruction and file shredding. It shreds data permanently by overwriting the existing data either on a hard drive or any other storage device. Removing files using AR 380-19 will block all the software and hardware-based recovery methods from extracting information.

The AR 380-19 method gets implemented in the following manner:

  • Pass 1: Writes a random character
  • Pass 2: Writes a specified character (e.g. zero)
  • Pass 3: Writes the complement of the specified character (i.e. one) and verifies the write

The AR 380-19 method is used incorrectly in data destruction programs, where it gets implemented without verification of the final pass or a third pass. NAVSO P-5239-26 and CSEC ITSG-06 are pretty similar to AR 380-19, with a chronology of the passes being the only difference in these methods.

Supporting programs: Eraser, PrivaZer, Delete Files Permanently, CBL Data Shredder

8. NAVSO P-5239-26  (US Navy)

NAVSO P-5239-26 is one of the data sanitization methods used to shred files. The program overwrites the existing data or information on a hard drive or any other storage device. Shredding data with NAVSO P-5239-26 will block all the software and hardware recovery methods to extract information from the drive.

NAVSO P-5239-26 wipe method has three passes and works in the following way:

  • Pass 1: Writes a specified character (e.g. one)
  • Pass 2: Writes the complement of the specified character (e.g. zero)
  • Pass 3: Writes a random character and verifies the write

The only difference between the NAVSO P-5239-26 and the AR 380-19 program is the changed chronology of passes. This program starts by writing a specified character in the first pass, either zero or one, while the AR 380-19 code writes a random character in the first pass.

9. RCMP TSSIT OPS-II

RCMP TSSIT OPS-II is a software-based data sanitization method used for shredding files or data destruction that overwrites the existing data or information on a hard drive or any other storage device. Shredding data with the RCMP TSSIT OPS-II will block all the software and hardware recovery methods to extract information from the drive and is the old standard followed by the Canadian government.

RCMP TSSIT OPS-II combines various methods like Write Zero method, Secure Erase, Random Data method and Gutmann methods altogether and works in the following pattern.

  • Pass 1: Writes a zero
  • Pass 2: Writes one
  • Pass 3: Writes a zero
  • Pass 4: Writes one
  • Pass 5: Writes a zero
  • Pass 6: Writes one
  • Pass 7: Writes a random character and verifies the write

This program can also be implemented by using random characters in place of zeros and ones if you want to avoid repetition. A verify pass repeats itself if the verification check fails.

Supported programs:  MHDD, CopyWipe, BCWipe, WipeDrive

10. CSEC ITSG-06 (The Canada RCMP Standard)

CSEC ITSG-06  is a data sanitation method used to overwrite the existing data and /information on a hard drive or any other storage device. Shredding data with the CSEC ITSG-06 will block all the software/hardware recovery methods to extract information from the drive.

CSEC ITSG-06 is different in terms of logic it uses as it combines zeroes and random characters. It is implemented in the following way:

  • Pass 1: Writes a one or zero
  • Pass 2: Writes the complement of the previously written character (e.g. one if Pass 1 was zero)
  • Pass 3: Writes a random character and verifies the write

Here you can customize the passes accordingly. CSEC ITSG-06 is vastly similar to NAVSO P-5239-26 and DoD 5220.02-M, the only difference being it doesn’t verify the first two writes like the latter.

Supported programs: Active KillDisk, CBL Data Shredder

11. HMG IS5 (Infosec Standard 5)

HMG IS5 is a data sanitization method used to shred files or data destruction that overwrites the existing data or information on a hard drive or any other storage device. Shredding data with HMG IS5 will block all the software/hardware recovery methods to extract information from the drive.

HMG IS5 combines two methods Write Zero and random data and gets implemented in the following way:

  • Pass 1: Writes a zero
  • Pass 2: Writes a one
  • Pass 3: Writes a random character and verifies the write

When the verification is done it likely means that the program needs to verify whether the data is actually overwritten. If the verification fails, the program will repeat that pass, or else you will get a message saying the action could not get completed.

Supported Programs: Eraser, Disk Wipe, Delete Files Permanently

12. ISM 6.2.92

ISM 6.2.92 is one of the best data sanitization methods that can block both software as well as hardware-based attempts to retrieve the overwritten data. It is a data shredding tool that completely overwrites data on a hard drive or a storage device and is the Australian government’s data sanitization standard.

ISM 6.2.92 is a bit different from other methods and works in the following direction:

  • Pass 1: Writes a random character and verifies the write

Usually, this method takes the decision depending upon the drive size. If the drive size is below 15 GB in size, the ISM 6.2.92 method will specify that the drive should be overwritten around three times with a random character.

This method has similarities with the Random Data wipe method. If verification is asked, it all means the data has gotten overwritten successfully. If it fails, you will get a message. ISM 6.2.92 method can be customized according to the user’s requirements.

Supported Programs: CBL Data Shredder, Hard Disk Scrubber.

13. NZSIT 402

NZSIT 402 is a data sanitization method that helps users in overwriting the existing data on a storage device. Shredding data with NZSIT 402 will block all the software/hardware recovery methods to extract information from the drive and is the New Zealand government’s data sanitization standard.

NZSIT 402 data deletion method works in the following way:

  • Pass 1: Writes a random character and verifies the write

NZSIT 402 method writes a random character in place of each bit of information on the device. It’s not necessary that the NZSIT 402 method will only use one pass; it can add on passes depending upon the program it is running.

Adding passes simply means that the random character is written over and over. If in case a program does not allow you to run multiple passes, then you can simply run this single pass over and over again.

Supported Programs:  Eraser, Disk Wipe, WipeFile, Privazer, Delete Files Permanently

14. VSITR

VSITR is a data sanitization method used for overwriting the existing data/information on a hard drive or any other storage device. Shredding data with VSITR will restrict all the software/hardware recovery methods to extract information from the drive.

VSITR sanitization method combines ones, zeroes, and random data to overwrite the data. It uses a total of 7 passes and is implemented in the following way:

  • Pass 1: Writes a zero
  • Pass 2: Writes a one
  • Pass 3: Writes a zero
  • Pass 4: Writes a one
  • Pass 5: Writes a zero
  • Pass 6: Writes a one
  • Pass 7: Writes a random character

One step you will not find here is the verification of written data. The method does not display any sort of verification.

Supported Programs:  Eraser, Secure Eraser, Delete Files Permanently, CBL Data Shredder, Hardwipe

15. GOST R 50739-95

GOST R 50739-95 is one of the data clearing methods used to shred files or data destruction that overwrites the existing data or information on a hard drive or any other storage device. Shredding data with GOST R 50739-95 restricts all the software/hardware recovery methods to extract information from the drive.

GOST R 50739-95 gets implemented in any of the two ways below:

  • Pass 1: Writes a zero
  • Pass 2: Writes a random character
  • Pass 1: Writes a random character

You may also find GOST R 50739-95 named as GOST by other data sanitization programs. Unlike other methods, the GOST R 50739-95 does not necessarily require verification to confirm whether the characters have been overwritten or not and is Russia’s data sanitization standard.

Supported Programs:  Delete Files Permanently, Eraser, Hardwipe, CBL Data Shredder, Hard Disk Scrubber.

16. The Gutmann method

Gutmann data sanitization

The Gutmann is one of the most popular and constantly used data sanitization methods. It was developed by Peter Gutmann in 1996. Shredding data with The Gutmann will disallow the recovery of data through software and is likely to restrict the same through hardware.

The Gutmann method works in the following unique manner. It has a single pass.

  • Pass 1 – 35: Writes a random character

This uses a random character for the first 4 and the last 4 passes whereas it uses a very complicated pattern of overwriting from Pass 5 to Pass 31. The Gutmann method is the most complex method to explain. It uses a unique table of the patterns in each of the passes.

If we see the definition and the complicated pattern The Gutmann method uses to overwrite the files, we will conclude that this method is the most secure one among all the methods. But that is not so.

The reason behind this is, The Gutmann method is the oldest data sanitization method found in the 90s. In that era, the hard drives were totally different as compared to today’s advanced drives. As the Gutmann method uses around 35 passes, most of the passes will have no meaning in today’s drives.

Supported programs: DBAN, CBL Data Shredder, Disk Wipe

17. The Schneier method

Created by Bruce Schneier, the Schneier method overwrites the data with a one and a zero and lastly with multiple passes of random characters. The Schneier method works in the following way

  • Pass 1: Writes a one
  • Pass 2: Writes a zero
  • Pass 3: Writes a stream of random characters
  • Pass 4: Writes a stream of random characters
  • Pass 5: Writes a stream of random characters
  • Pass 6: Writes a stream of random characters
  • Pass 7: Writes a stream of random characters

It may give you a verification after the first or last pass. The customizing method will work, but then it will remain The Schneier method.

Supported programs:  Eraser, Securely File Shredder, CBL Data Shredder, Delete Files Permanently

18. The Pfitzner method

The Pfitzner data wipe method, created by Roy Pfitzner, is a data sanitization method that stops all the software-based attempts to retrieve the overwritten data and does the same with some of the hardware-based methods. However, it is incapable of advanced hardware techniques of data retrieval.

The Pfitzner method gets implemented the following way, but the number of passes depends upon the software implementing the method.

  • Pass 1 – 33: Writes a random character

It is sometimes written as Pfitzner 33-pass, Pfitzner 7-pass, random(x33) or random(x7).

The Pfitzner method program overwrites data with random characters 33 times. If you run this method for example 40 times, the software will overwrite the drive, not 33 times but 1,320 times (33×40). With some software applications, you may get verification for successful overwriting.

Supported programs:  DBANCBL Data Shredder, BitRaser, Scrub

Final Thoughts on Data Sanitization

Data sanitization is defined as the process of irreversibly destroying data stored on a hard drive or a storage device. Once you have executed a particular data wiping method, the lost data cannot be recovered in most of the cases through software or hardware.

However, some methods still have loopholes and data can be retrieved through advanced hardware-based techniques if they are used. Examples of such methods are the Gutmann method and the Pfitzner method. The Gutmann method should be avoided as it is the oldest data sanitization method built for the kind of hard drives made in the 90s.

There are different methods of data shredding and data destruction used by various software programs. The choice of the method depends upon the level of security the user wants to add the data he chooses to overwrite on.

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