4.7.1.2. Erasure Options

Erasing Algorithm

Description

Zeroes

This algorithm erases data by overwriting it with zeros in a single pass. This is the fastest algorithm available to a user.

Pseudo-random

This algorithm erases data by overwriting an entire hard drive with randomly generated numbers in a single pass.

US Department of Defense, DoD 5220.22-M (3 passes)

This algorithm erases data by overwriting the hard drive in three passes. In the first pass, it overwrites data with zeros, then in the second pass, it overwrites the data with ones and finally in the third pass overwrites the data with randomly generated bytes. This is a U.S. Department of Defense algorithm.

Pseudo-random & Zeroes (2 passes)

This algorithm erases data by overwriting the hard drive in two passes. In the first pass, it overwrites data with randomly generated numbers and in the second pass, it overwrites the previously generated data with zeros.

Random Random Zero (6 passes)

This algorithm erases data by overwriting a storage media with random characters in multiple passes.

US Department of Defense, DoD 5220.22-M (ECE) (7 passes)

This algorithm erases data by overwriting the hard drive in seven passes. The first, fourth and fifth pass is overwriting with a random byte, its 8 right-bit shift complement and 16 right-bit shift complement; second and sixth passes are overwriting with zeros, and third and seventh pass with random data. This is a U.S. Department of Defense algorithm.

US Department of Defense, DoD 5200.28-STD (7 passes)

This algorithm erases data by overwriting the hard drive in seven passes. In the first two passes, it overwrites data with certain bytes and their complements, then in the next two passes, it overwrites data with random characters. In the fifth and sixth passes, it overwrites data with a character and its complements and finally, it overwrites data with random characters. This is a U.S. Department of Defense algorithm.

Russian Standard - GOST-R-50739-95(2 passes)

This algorithm erases data by overwriting the hard disk with zeros followed by a single pass of random characters.

B.Schneier's algorithm (7 passes)

This algorithm erases data in seven passes. In the first two passes, it overwrites the hard disk with ones and then zeros and in the next five passes, it overwrites data with random characters.

German Standard, VSITR (7 passes)

This algorithm erases data by overwriting data with three alternating patterns of zeros and ones and then the last pass which overwrites with random characters.

Peter Gutmann, (35 passes)

This algorithm erases data by overwriting it 35 times, making recovery of the erased data by any tool impossible. This algorithm takes more time than other wiping algorithms.

US Army AR 380-19 (3 passes)

This algorithm erases data by overwriting the media in three passes. In the first pass, it overwrites data with random bytes, then in the second and third pass, it overwrites data with certain bytes and their complements. This is a U.S. Army algorithm.

North Atlantic Treaty Organization-NATO Standard (7 passes)

This algorithm erases data by overwriting the media in seven passes. From pass one to six, it overwrites the data with a number and its complement alternatively. Then, in the final pass, it overwrites data with random characters.

US Air Force, AFSSI 5020 (3 passes)

This algorithm erases the data by overwriting the media in three passes. First, it overwrites with zeros, then with ones and finally with random characters.

Pfitzner algorithm (33 passes)

The Pfitzner algorithm is used in file shredding and data destruction programs to overwrite existing information on a hard drive or other storage devices. All the passes in the Pfitzner method consist entirely of random overwriting of data in the storage device.

Canadian RCMP TSSIT OPS-II (4 passes)

This algorithm is four pass overwriting algorithm with alternating patterns of zeros and ones and the last pass - with a random byte.

British HMG IS5 (3 passes)

This algorithm is a three pass overwriting algorithm: first pass with zeros, second pass with ones and the last pass with random data.

NIST 800- 88 Clear

This algorithm overwrites media by using organizationally approved and validated overwriting technologies/methods/tools.

Verification Methods

Description

No Verification

No verification is done after the traces are erased.

Random Verification

Random verification of the storage device is done after the erasing operation, that is, randomly selected sectors of the storage device are verified after erasing operation.

Total Verification

Total verification verifies all the sectors of the storage device after the erasing operation is completed.