Data Sanitization

I found some interesting materials to the topic of data sanitization:

Magnetic Media - (Peter Gutmann - oldies but interesting):
- note the old drives, low density, MFM/LCC - able to recover complements by osciloscipe reading
- read epilogue - 35-vodoo overwriting scheme not necessary for modern drives, radom data would do the trick

Semiconductors (Peter Gutmann - SRAM, DRAM,EEPROM, FLASH ...)

And recommended tools :D by Peter:

Data remanence
- Feasibility of recovery

Microscopy of HDD data
- micro imaging would take at least weeks on todays high density high volume drives

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DoD 5220.22-M NISPOM
8-306. Maintenance - Clearing and Sanitization Matrix
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.

AR380-19

Degausser for HDD - maybe we could use one for broken drives:
http://www.mediaduplicationsystems.com/Degausser_Hard_Drive_Degaussers_s/103.htm
http://www.datalinksales.com/detail/Model%201100.html/1100%20degauss%20wand

Additional topics:
HPA and DCO protected areas on ATA drives

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My personal conclusions:
Working drives:
- even one verified zero overwrite the drive should be good enough for "For Internal Use" data.
- actually this is what "ATA Secure Erase" does
- even one random data overwrite the drive should be good enough for pretty much everything
- I find it highly non-economical to invest so much money and effort to read overwritten data
- DoD 5220.22-M with 3 overwrites - to be on safe side from audit


Broken drives:
- if suffering from badblocks "ATA Enhanced Secure Erase" still might help - although no fancy logs or reports of results
- hammer and drill is your friend :) for completely non-working discs
- I was surprised that HDD degaussers are quite affordable