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-5239-26MFM | 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-5239-26RLL | 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 OrganizationNATO 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 |