[ale] Wiping hard drives revisited...

[mhw at WittsEnd.com (Michael H. Warfield)]

Hey all,

	I think it was after my talk on extreme data recovery that several of
us got into the old discussion over wiping data and number of passes and
recovering data with a microscope and all.  My position for a long time
has been that it's virtually impossible with modern high density hard
drives and the old "multiple pass" wisdom was largely from the days of
tapes (reel to reel tapes tapes at that).  I don't recall who was
arguing the counterpoint that they could recover data with a magnetic
field microscope and all.  Seems that someone has actually gone and
researched it and actually tested it.  Thought everyone would find this
interesting as a follow on to that debate:

	Single drive wipe protects data, research finds
	http://www.securityfocus.com/brief/888

	Single pass wipe: "Recovering a single byte of data, for example, on a
used drive is successful less than one percent of the time, he found.
Accurately recovering four bytes, or 32 bits, of data only works nine
times out of each million tries."

	"In many instances, using a MFM (magnetic force microscope) to
determine the prior value written to the hard drive was less successful
than a simple coin toss."

-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0xDF1DD471        | possible worlds.  A pessimist is sure of it!

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