John R Pierce wrote: > On 5/31/2017 10:13 AM, m.roth at 5-cent.us wrote: >> If I had realized it would run this long, I would have used DBAN.... For >> single drives, I do, and choose DoD 5220.22-M (seven passes), which is >> *way* overkill these days... but I sign my name to a certificate that >> gets stuck on the outside of the server, meaning I, personally, am >> responsible for the sanitization of the drive(s). > > the DoD multipass erase procedure is long obsolete and deprecated. It > was based on MFM and RLL technology prevalent in the mid 1980s. NISPOM > 2006-5220 replaced it in 2006, and says "DESTROY CONFIDENTIAL/SECRET > INFORMATION PHYSICALLY". > > http://www.infosecisland.com/blogview/16130-The-Urban-Legend-of-Multipass-Hard-Disk-Overwrite.html > http://www.dss.mil/documents/odaa/nispom2006-5220.pdf > > from that blog,... > >> Fortunately, several security researchers presented a paper [WRIG08 >> <http://www.springerlink.com/content/408263ql11460147/>] at the Fourth >> International Conference on Information Systems Security (ICISS 2008) >> that declares the “great wiping controversy” about how many passes of >> overwriting with various data values to be settled: their research >> demonstrates that a single overwrite using an arbitrary data value >> will render the original data irretrievable even if MFM and STM >> techniques are employed. >> >> The researchers found that the probability of recovering a single bit >> from a previously used HDD was only slightly better than a coin toss, >> and that the probability of recovering more bits decreases >> exponentially so that it quickly becomes close to zero. >> >> Therefore, a single pass overwrite with any arbitrary value (randomly >> chosen or not) is sufficient to render the original HDD data >> effectively irretrievable. > > so a single pass of zeros is plenty adequate for casual use, and > physical device destruction is the only approved method for anything > actually top secret. Not dealing with "secret", dealing with HIPAA and PII data. And *sigh* Homeland Security Theater dictates.... mark