US Department of Defense in the clearing and sanitizing standard DoD 5220.22-M recommends the approach "Overwrite all addressable locations with a character, its complement, then a random character and verify" (see table with comments) for clearing and sanitizing information on a writable media.
To conform this security standard in Active@ KillDisk Professional version this approach has been implemented, i.e. triple data overwriting for the destruction of remains of sensitive data.
| Media | Clear | Sanitize |
|---|---|---|
| Magnetic Tape1 | ||
| Type I | a or b | a, b, or m |
| Type II | a or b | b or m |
| Type III | a or b | m |
| Magnetic Disk | ||
| Bernoullis | a, b, or c | m |
| USBs(floppys) | a or b | b or m |
| Non-Removable Rigid Disk | c | a, b, d , or m |
| Removable Rigid Disk | a, b, or c | a, b, d , or m |
| Optical Disk | ||
| Read Many, Write Many | c | m |
| Read Only | m,n | |
| Write Once, Read Many (Worm) | m, n | |
| Memory | ||
| Dynamic Random Access memory (DRAM) | c or g | c, g, or m |
| Electronically Alterable PROM (EAPROM) | i | j or m |
| Electronically Erasable PROM (EEPROM) | i | h or m |
| Erasable Programmable (ROM (EPROM) | k | l, then c, or m |
| Flash EPROM (FEPROM) | i | c then i, or m |
| Programmable ROM (PROM) | c | m |
| Magnetic Bubble Memory | c | a, b, c, or m |
| Magnetic Core Memory | c | a, b, e, or m |
| Magnetic Plated Wire | c | c and f, or m |
| Magnetic Resistive Memory | c | m |
| Nonvolatile RAM (NOVRAM) | c or g | c, g, or m |
| Read Only Memory ROM | m | |
| Static Random Access Memory (SRAM) | c or g | c and f, g, or m |
| Equipment | ||
| Cathode Ray Tube (CRT) | g | q |
| Printers | ||
| Impact | g | p then g |
| Laser | g | o then g |
a. Degauss with a Type I degausser
b. Degauss with a Type II degausser.
c. Overwrite all addressable locations with a single character.
d. Overwrite all addressable locations with a character, its complement, then a random character and verify.
THIS METHOD IS NOT APPROVED FOR SANITIZING MEDIA THAT CONTAINS TOP SECRET INFORMATION.
e. Overwrite all addressable locations with a character, its complement, then a random character.
f. Each overwrite must reside in memory for a period longer than the classified data resided.
g. Remove all power to include battery power.
h. Overwrite all locations with a random pattern, all locations with binary zeros, all locations with binary ones.
i. Perform a full chip erase as per manufacturer's data sheets.
j. Perform i above, then c above, a total of three times.
k. Perform an ultraviolet erase according to manufacturer's recommendation.
l. Perform k above, but increase time by a factor of three.
m. Destroy - Disintegrate, incinerate, pulverize, shred, or melt.
n. Destruction required only if classified information is contained.
o. Run five pages of unclassified text (font test acceptable).
p. Ribbons must be destroyed. Platens must be cleaned.
q. Inspect and/or test screen surface for evidence of burned-in information. If present, the cathode ray tube must be destroyed.
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