Bugtraq mailing list archives
Re: Peter Gutmann data deletion theaory?
From: Casper.Dik () Sun COM
Date: Sat, 23 Jul 2005 10:27:54 +0200
His theory no longer does hold true. His 1996 paper is available at http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html, targeting MFM and RLL disk technology, where a typical 5.25" disk held 20-80MB (yes, MEGAbyte, not GB). His recommendations were based on old magnetic disc technology where each bit was represented by the magnetical orientation on the platter (north=1, south=0). After that came other technologies, where bits are defined by changes of the magnetic field even down to probabilistic field measurements - which allowes tighter data packing but rendered the base of his recommendations useless.
Overwriting the data a couple of times seems to be relatively effective for modern disks. In my opninion, the best way to destroy your data is to keep it encrypted and then destroy the keys. Recovery will succeed in only recovering a fraction of the data; but with an unknown key and a typical encryption algorithm where a single bit changed in the input changes all bits in the output, recovery will need to find quite a bit more than the 1 bit per byte required to recover typical text.
OTOH I have seen one company with a *really* thorough disk & tape cleaning technique: 1. writing zeroes all over 2. low level format 3. shredding the disc drive into small pieces 4. magnet treatment of the scrap metal 5. burning in their own waste incinerating plant
Note that many of the people using such technologies do this to prevent against future breakthrouhgs in recovery technology. So it's required only for data with a long half-life. Casper
Current thread:
- Peter Gutmann data deletion theaory? Jared Johnson (Jul 21)
- RE: Peter Gutmann data deletion theaory? Barbara Lockwood (Jul 21)
- RE: Peter Gutmann data deletion theaory? Tiago Halm (Jul 22)
- Re: Peter Gutmann data deletion theaory? Jay D. Dyson (Jul 21)
- Re: Peter Gutmann data deletion theaory? Thor (Hammer of God) (Jul 22)
- Re: Peter Gutmann data deletion theaory? Simple Nomad (Jul 21)
- Re: Peter Gutmann data deletion theaory? Volker Tanger (Jul 22)
- Re: Peter Gutmann data deletion theaory? Alexander L. Ivanchev (Jul 27)
- Re: Peter Gutmann data deletion theaory? Casper . Dik (Jul 27)
- Re: Peter Gutmann data deletion theaory? Vincent DUVERNET (Nolmë Informatique) (Jul 22)
- Re: Peter Gutmann data deletion theaory? Jake Appelbaum (Jul 27)
- RE: Peter Gutmann data deletion theaory? Jared Johnson (Jul 22)
- Re: Peter Gutmann data deletion theaory? Volker Tanger (Jul 22)
- RE: Peter Gutmann data deletion theaory? D. Weiss (Jul 22)
- Re: Peter Gutmann data deletion theaory? Dana Hudes (Jul 22)
- Re: [BugTraq] Peter Gutmann data deletion theaory? Robin Whittle (Jul 22)
- Re: [BugTraq] Peter Gutmann data deletion theaory? Volker Kuhlmann (Jul 27)
- RE: Peter Gutmann data deletion theaory? dave kleiman (Jul 27)
- <Possible follow-ups>
- RE: Peter Gutmann data deletion theaory? Jeremy Epstein (Jul 21)
- RE: Peter Gutmann data deletion theaory? Glenn.Everhart (Jul 21)
(Thread continues...)
- RE: Peter Gutmann data deletion theaory? Barbara Lockwood (Jul 21)