| Wipe Method |
Definition |
Security |
Grade
1. Super Fast Zero Write |
This
method will overwrite the target data area with a fixed value
(0x00) on every 3rd sector. |
Low |
Grade
2. Fast Zero Write |
This
method will overwrite the target data area with a fixed value
(0x00) on every other sector.
|
Low |
Grade
3. Zero Write |
This
method will overwrite the target data area with a fixed value
(0x00) throughout the entire area. |
Low |
Grade
4. Random Write |
Overwrites
the target data area with random values. The user selects the
number of passes, from 1 to 9 |
Medium
|
Grade
5. Random & Zero Write |
After
overwriting the target data area with random values, it will
overwrite once again with a fixed value (0x00) overwrites with
random values and then with zero; more secure than zero write. |
Medium
|
Grade
6. US Navy, NAVSO P-5239-26
MFM |
This
is the US Navy standard NAVSO P-5239-26 for MFM encoded drives.
This deletion method first writes the fixed value (0xffffffff)
to the target data area, then the fixed value (0xbfffffff) and
then random values. Finally, the target data area is read to
verify the overwrites |
Medium
|
Grade
7. US Navy, NAVSO P-5239-26
RLL |
This
is the US Navy standard NAVSO P-5239-26 for RLL encoded drives.
This deletion method first writes the fixed value (0xffffffff)
to the target data area, then the fixed value (0x27ffffff) and
then random values. Finally, the target data area is read to
verify the overwrites. |
Medium
|
Grade
8. Bit Toggle |
This
method will overwrite the target data area four times, first
with the value (0x00), then with the value (0xff), then (0x00),
then (0xff). |
Medium
|
Grade
9. Random Random Zero |
This
method first overwrites the target data area twice with random
values, then once more with the fixed value (0x00). Overwrites
twice with random values and then once with zeros; more secure
than Random & Zero Write |
Medium
|
Grade
10. US Department of Defense (DoD 5220.22-M) |
The
deleting method was introduced by the US Department of Defense
(Pentagon) and is known as “DoD5220.22-M”.
It will overwrite the target data area first by writing a fixed
value (in our case, 0x00) once, then its compliment value (in
our case, 0xff) once and finally random values once. After the random value overwrite is complete, the disk is
read to verify the overwrites. |
Medium |
Grade
11. US Air Force, AFSSI5020 |
This
is the US Air Force standard AFSSI5020. This deletion method
first overwrites the target data area with the fixed value
(0x00), then with the fixed value (0xff) and then with a
randomly selected constant. Finally, at least 10% of the drive
is read to verify the overwrites |
Medium |
Grade
12. North Atlantic Treaty Organization
NATO standard
|
This
method is the deletion standard of North Atlantic Treaty
Organization (NATO). It will overwrite the target data area 7
times. The first six overwrites are with the fixed values (0x00)
and (0xff), alternating between passes. The 7th overwrite is
with a random value |
High |
Grade
13. Peter Gutmann Secure Deletion |
This
method was introduced by Peter Gutmann in the year 1996. This is perhaps the most secure deletion method
available. It will overwrite the target data area by writing random
values four times on each sector. Next, it will overwrite the
target data area with carefully chosen fixed values on each
sector, 27 times. Finally, it will write random values 4 times
on each sector. This is 35 write passes in total. |
High
|
Grade
14. US Department of Defense (DoD 5220.22-M) + Gutmann Method |
This
is very secure deletion. It will use the US Department of
Defense (DoD5220.22-M) standard method followed by the Gutmann
deletion method. |
Very
High |
