Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you!
At 02:17 AM 7/2/97 -0000, Secret Squirrel wrote:
Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you!
Mini-FAQ: 1. How do I degauss magnetic media so that the feds can no longer read my data? You don't. That's why the feds themselves don't degauss their magnetic media for declassification purposes. They remove the oxide layer. In case of floppies the preferred method is incineration, in case of hard drives, the usual technique is sandblasting. --Lucky Green <shamrock@netcom.com> PGP encrypted mail preferred. DES is dead! Please join in breaking RC5-56. http://rc5.distributed.net/
Lucky Green <shamrock@netcom.com> writes:
media for declassification purposes. They remove the oxide layer. In case of floppies the preferred method is incineration, in case of hard drives, the usual technique is sandblasting.
5.25" floppies could be run via a shredder (a big one, not the puny little thing I have at home) but 3.5" floppies would make almost any shredder choke. Some large corporations sell their old floppies to China, where they're supposedly recycled into magentic strips for credit cards. Hmm... --- Dr.Dimitri Vulis KOTM Brighton Beach Boardwalk BBS, Forest Hills, N.Y.: +1-718-261-2013, 14.4Kbps
Lucky Green wrote :
At 02:17 AM 7/2/97 -0000, Secret Squirrel wrote:
Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you!
Mini-FAQ: 1. How do I degauss magnetic media so that the feds can no longer read my data?
You don't. That's why the feds themselves don't degauss their magnetic media for declassification purposes. They remove the oxide layer. In case of floppies the preferred method is incineration, in case of hard drives, the usual technique is sandblasting.
This may also have to do with the many documented instances when federal hard drives, including some from NSA computers, were sold surplus unerased with significant sensitive information still intact on them (I know personally of once such incident of many). Destroying the disks makes sure that they were, in fact, rendered unreadable and not just signed off on by some bored low paid clerk charged with demilitizing them who didn't want to bother to figure out how to erase them. The problem here is that a destroyed disk is obviously unreadable to even the most dumb and unmotivated clerk with a GED, while a merely erased disk looks just exactly like one full of sensitive information - actually verifying that the information is in fact entirely gone requires a lot of technical skill and is subject to all kinds of false positives (how about sectors that contained sensitive stuff and then were later marked bad and swapped with alternates, for example ? ) I think all of us forget that the usual key to crypto protected secrets is in the trash and surplus equipment and document disposal practices of the target rather than advanced mathematics. And most technical people pay as little attention as they possibly can to what happens with the old floppies left by Joe who quit to take a new job or what happened to Sallie's old hard drive after she got the new computer, or whether the old backup tapes really are all fully accounted for or were thrown out in the move... I applaud the government for forgoing a few dollars in residual revenue by not selling old disks intact any more. Dave Emery die@die.com
At 02:17 AM 7/2/97 -0000, Secret Squirrel wrote:
Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you!
Electromagnetic pulse. You want something as strong as possible. About 10 megatons should generate a big enough pulse. --- | "That'll make it hot for them!" - Guy Grand | |"The moral PGP Diffie taught Zimmermann unites all| Disclaimer: | | mankind free in one-key-steganography-privacy!" | Ignore the man | |`finger -l alano@teleport.com` for PGP 2.6.2 key | behind the keyboard.| | http://www.ctrl-alt-del.com/~alan/ |alan@ctrl-alt-del.com|
At 10:02 PM -0700 7/1/97, Alan Olsen wrote:
At 02:17 AM 7/2/97 -0000, Secret Squirrel wrote:
Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you!
Electromagnetic pulse. You want something as strong as possible. About 10 megatons should generate a big enough pulse.
It works better if you also expose it to the heat and blast. :-) In all seriousness, complete physical destruction of the media is the only sure technique. Lucky Green's sandblasting sounds like it should work well. Melting it into slag should also work. ------------------------------------------------------------------------- Bill Frantz | The Internet was designed | Periwinkle -- Consulting (408)356-8506 | to protect the free world | 16345 Englewood Ave. frantz@netcom.com | from hostile governments. | Los Gatos, CA 95032, USA
On Tue, 1 Jul 1997, Bill Frantz wrote:
At 10:02 PM -0700 7/1/97, Alan Olsen wrote:
At 02:17 AM 7/2/97 -0000, Secret Squirrel wrote:
Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you!
Electromagnetic pulse. You want something as strong as possible. About 10 megatons should generate a big enough pulse.
It works better if you also expose it to the heat and blast. :-)
In all seriousness, complete physical destruction of the media is the only sure technique. Lucky Green's sandblasting sounds like it should work well. Melting it into slag should also work.
That reminds me... I have some old drives I need to take down to the shooting range. (I want to make them an example to the other drives...) Sounds like a Cypherpunk project to me. ]:> alano@teleport.com | "Those who are without history are doomed to retype it."
The Cypherpunks Shooting Club welcomes you each Sunday immediately following the monthly CP meeting. Except this August, when certain stalwart members of the club will be at HIP'97. :-) -- Lucky Green <mailto:shamrock@netcom.com> PGP encrypted mail preferred On Wed, 2 Jul 1997, Alan wrote:
On Tue, 1 Jul 1997, Bill Frantz wrote:
At 10:02 PM -0700 7/1/97, Alan Olsen wrote:
At 02:17 AM 7/2/97 -0000, Secret Squirrel wrote:
Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you!
Electromagnetic pulse. You want something as strong as possible. About 10 megatons should generate a big enough pulse.
It works better if you also expose it to the heat and blast. :-)
In all seriousness, complete physical destruction of the media is the only sure technique. Lucky Green's sandblasting sounds like it should work well. Melting it into slag should also work.
That reminds me... I have some old drives I need to take down to the shooting range. (I want to make them an example to the other drives...)
Sounds like a Cypherpunk project to me. ]:>
alano@teleport.com | "Those who are without history are doomed to retype it."
At 01:29 AM 7/3/97 -0500, snow wrote:
The Cypherpunks Shooting Club welcomes you each Sunday immediately following the monthly CP meeting. Except this August, when certain stalwart members of the club will be at HIP'97. :-)
What date will the meeting be?
The regular CP meeting is always on the second Saturday of the month. The meeting at HIP will be the same day: August 9 at the HIP campground. I'll be the guy in the black BDU with the "L. Green" name tag, wearing a Nomex balaklava. :-) --Lucky --Lucky Green <shamrock@netcom.com> PGP encrypted mail preferred. DES is dead! Please join in breaking RC5-56. http://rc5.distributed.net/
Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you!
I guess this is what you are looking for: http://www.cs.auckland.ac.nz/~pgut001/secure_del.html
Could someone please point me to a FAQ or somesuch about degaussing magnetic media? Thank you! http://www.cs.auckland.ac.nz/~pgut001/secure_del.html
Thanks for posting a marvelous reference on erasing media. Technology changes have a substantial effect on what's adequate and what's not. Back in the mid-late 80s, when I was a tool of the military-industrial complex, we had the offical rules for declassifying media; I think they were from Army Reg 380-380. For disk drives and magtapes, you had the choice of physical destruction, running an NSA-approved overwrite program, or using an NSA-approved BF magnet for degaussing. We didn't have an approved program for Vax UNIX, not that I would have trusted it to clean mapped-out bad sectors, and any magnet that could suck the bits off a hard disk was bigger than I was going to allow near my computers or mag tape collection, thank you very much. Floppy disks make a satisfying squooshy sound in a shredder; remember to take the cardboard jacket off the floppy first. Reeling out 9-track tape into a shredder is boring, but works. I was no longer around when they sandblasted the RM05 packs, but the sysadmin after me had a good time doing it, and instead of the usual head-crashed RM05 platter on her wall, she had one that was sandblasted real clean :-) For memory, you needed to run an NSA-approved program on your machine that would overwrite each byte three (?) times; the trick was making sure your operating system would let you get at everything, and of course moving the program while it was running so it wouldn't overwrite itself. I don't know if anyone remembered to do that after decommissioning the VAX; we didn't do it when switching between the classified operating system diskpacks and the VMS maintenance system, but we still maintained physical control of the system so it was OK. Technology changes make a lot of difference in how you operate; When we were using Vaxen with large RM05 removable disks, we'd keep the main copy of the operating system up and running, and needed to pay a lot of attention to security (in spite of most of our users having the root password :-), and the disk packs took up lots of space in the safe. Later we started using PCs, and any special project that didn't want to run on the main Vax just kept a few floppies in the safe, or if it had a hard disk, they could put the whole PC in the safe. With Sun workstations, we switched over to using shoebox disks, which were very convenient... Now if I were in that business, I suppose I'd use Jazz drives, or the large Syquest drives, and keep the operating system on a read only hard drive... # Thanks; Bill # Bill Stewart, +1-415-442-2215 stewarts@ix.netcom.com # You can get PGP outside the US at ftp.ox.ac.uk/pub/crypto/pgp # (If this is a mailing list or news, please Cc: me on replies. Thanks.)
participants (10)
-
3umoelle＠informatik.uni-hamburg.de -
Alan -
Alan Olsen -
Bill Frantz -
Bill Stewart -
Dave Emery -
dlv＠bwalk.dm.com -
Lucky Green -
Secret Squirrel -
snow