'Purge' is defined by NIST as: “Purge applies physical or logical techniques that render Target Data recovery infeasible using state of the art laboratory techniques” (pg. 9 of “NIST Special Publication 800-88 Revision 1--Guidelines for Media Sanitization”).
'Clear' is defined by NIST as: “Clear applies logical techniques to sanitize data in all user-addressable storage locations for protection against simple non-invasive data recovery techniques; typically applied through the standard Read and Write commands to the storage device, such as by rewriting with a new value or using a menu option to reset the device to the factory state (where rewriting is not supported)” (pg. 9 of “NIST Special Publication 800-88 Revision 1--Guidelines for Media Sanitization”).
'Unknown' means that neither 'Clear' or 'Purge' had been met due one or more of the following reasons.
- The wipe(s) weren't verified properly or at all.
- The media type isn't handled by the product or simply cannot be classified per to the NIST specification.
- The drives are part of a RAID array.
- A DCO lock on the drive wasn't removed.
- A Failure on the drive was reported.
Below is a list of possible NIST Classifications based on the different media types and overwrite methods. Although these results are from running the NIST pattern specifically, any wipe pattern can classify as NIST when a verify of +10% is performed after the last pass.
NVMe
Manual Overwrite (3 pass w/ verify): Clear
Enhanced Secure Erase: Purge
Sanitize Device Block Erase: Purge
Sanitize Device Crypto Scramble: Purge
Sanitize Device Overwrite: N/A
OPAL Crypto Scramble: Purge
SSD
Manual Overwrite (3 pass w/ verify): Clear
Enhanced Secure Erase: Clear
Sanitize Device Block Erase: Purge
Sanitize Device Crypto Scramble: Purge
Sanitize Device Overwrite: N/A
OPAL Crypto Scramble: Purge
HDD (Platter)
Manual Overwrite (3 pass w/ verify): Clear
Enhanced Secure Erase: Purge
Sanitize Device Block Erase: N/A
Sanitize Device Crypto Scramble: Purge
Sanitize Device Overwrite: Purge
OPAL Crypto Scramble: Purge
SSHD (Hybrid)
Manual Overwrite: Unknown
Enhanced Secure Erase: Unknown
Sanitize Device Block Erase: Unknown
Sanitize Device Crypto Scramble: Unknown
Sanitize Device Overwrite: Unknown
OPAL Crypto Scramble: Unknown
USB & MMC
Manual Overwrite (2-pass w/ verify): Clear
Enhanced Secure Erase: N/A
Sanitize Device Block Erase: N/A
Sanitize Device Crypto Scramble: N/A
Sanitize Device Overwrite: N/A
OPAL Crypto Scramble: N/A
