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.
|Type I||a or b||a, b, or m|
|Type II||a or b||b or m|
|Type III||a or b||m|
|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|
|Read Many, Write Many||c||m|
|Write Once, Read Many (Worm)||m, n|
|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|
|Cathode Ray Tube (CRT)||g||q|
|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.