Re: howto clean disks ?
Diana Eichert wrote: On Wed, 1 Jun 2005, Anthony Roberts wrote: The 'dd' way is good enough unless someone is willing to to tear the drive apart in a lab. Items required for sure fire disk cleaning methodology. qty. 1 hard drive to clean qty. 1 high velocity military rifle I usually use a .223 round, but other parts of the world may prefer .308(7.62x51) or 7.62x54. qty. what number of rounds you feel like of previously described firearm I just take an axe to the disk.
Re: howto clean disks ?
Baldur Sigurpsson wrote: Ed White wrote: Hi, I'm going to give away some old hard disks and I'm planning to delete/overwrite all the data on them. Is there any tool to make this automagically ? Thanks. Can't you just have the hole partition encrypted, I've never actually encountered information about how to do it on OBDS, but the NetBSD guide explains how to do it in details. That way nobody will be able to unencrypt it unless he has the password, right? But then again, they might try some nasty tricks on you to get the password..., but hopefully not ;) Regards, Baldur Here is a HOWTO on building a fileserver with OpenBSD, I guess you could use parts of it to do it. (Don't know if the link works though, I had it in my bookmarks and I can't access port 81 when I'm in school). http://pooh.selwerd.nl:81/index.php?id=83 Regards, Gupni
Re: howto clean disks ?
The OP is donating old hard disks and wants to ensure his data is non-recoverable. Why in the hell would he encrypt the disk before giving it away? You and the next are way off topic. Someone stick a fork in this thread; I think it's done. - Matt Baldur Sigurpsson wrote: Ed White wrote: Hi, I'm going to give away some old hard disks and I'm planning to delete/overwrite all the data on them. Is there any tool to make this automagically ? Thanks. Can't you just have the hole partition encrypted, I've never actually encountered information about how to do it on OBDS, but the NetBSD guide explains how to do it in details. That way nobody will be able to unencrypt it unless he has the password, right? But then again, they might try some nasty tricks on you to get the password..., but hopefully not ;) Regards, Baldur
Re: howto clean disks ?
Ed White wrote: Hi, I'm going to give away some old hard disks and I'm planning to delete/overwrite all the data on them. Is there any tool to make this automagically ? badblocks -s -v -w device I usually keep a Knoppix CD around for this purpose, but its also available in the e2fsprogs port. -- ach
Re: howto clean disks ?
Results can be a bit, ... interesting if there is a Linux swap partition in existence. (That's partition as in DOS/Windows/Linux, not partition as in BSD) The swap is activated by default and the verification errors can be interesting. badblocks probably gives better assurance that the disk is in fact useable. seems like dd will error and quit if there is a hard error before the end. flames invited if I am in error. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Andy Hayward Sent: Thursday, June 02, 2005 6:06 AM To: [EMAIL PROTECTED] Cc: misc@openbsd.org Subject: Re: howto clean disks ? Ed White wrote: Hi, I'm going to give away some old hard disks and I'm planning to delete/overwrite all the data on them. Is there any tool to make this automagically ? badblocks -s -v -w device I usually keep a Knoppix CD around for this purpose, but its also available in the e2fsprogs port. -- ach
Re: howto clean disks ?
The 'dd' way is good enough unless someone is willing to to tear the drive apart in a lab.
Re: howto clean disks ?
On 6/1/05, Shane J Pearson [EMAIL PROTECTED] wrote: On 01/06/2005, at 4:01 PM, Anthony Roberts wrote: On 6/1/05, Ed White [EMAIL PROTECTED] wrote: I'm going to give away some old hard disks and I'm planning to delete/overwrite all the data on them. Is there any tool to make this automagically ? If these are SCSI drives, you should additionally consider doing a low-level format. Many SCSI controller BIOS interface menus offer a format option, this will do a true low-level drive format. The 'dd' way is good enough unless someone is willing to to tear the drive apart in a lab. I think this depends on how you use dd though. If you just do a single pass of zeroes, but fear someone will mount a multi million dollar electron microscope forensic analysis, then yeah, that might not be enough. Back to OpenBSD, if you never let sensitive data hit the disk in the clear (through the use of cfs and encrypted swap), the question of how best to wipe the disks no longer needs to be asked. But write from /dev/urandom with dd multiple times to the disk and you should be okay even with that extreme case. If I were worried about open-drive analysis of the drive I want to clean, then I'd be physically destroying the drive also. Put it in a kiln, get the oxy torch into it, etc. I read the Ed's question as implying that he wanted the recipient to be able to get some use out of the drives, as something more than a paperweight. Kevin Kadow (P.S. Before anybody else learns this the hard way, *successfully* degaussing a hard drive, while not physically destructive, also renders the drive useless for all but paperweight duty.)
Re: howto clean disks ?
If you are truly paranoid use DBAN, which is short for Darin's Boot and Nuke. IMO it is the best disk wiping tool out there. It gives you a couple different wiping methods to choose from, including the one used by the US DoD. You can also specify how many passes it makes. According to the website, DBAN is used by the US Dept of Energy and the National Nuclear Security Administration, which ain't bad. Be aware that it may take an entire day to run depending on which wipe method you choose. I called it good after around 8 hours, and I was only on pass 5/7 on an 80GB disk! It has a quick wipe option if you don't want to wait forever or aren't insanely paranoid. http://dban.sourceforge.net/ - Matt Shane J Pearson wrote: Hi Anthony, On 01/06/2005, at 4:01 PM, Anthony Roberts wrote: The 'dd' way is good enough unless someone is willing to to tear the drive apart in a lab. I think this depends on how you use dd though. If you just do a single pass of zeroes, but fear someone will mount a multi million dollar electron microscope forensic analysis, then yeah, that might not be enough. But write from /dev/urandom with dd multiple times to the disk and you should be okay even with that extreme case. If I were worried about open-drive analysis of the drive I want to clean, then I'd be physically destroying the drive also. Put it in a kiln, get the oxy torch into it, etc.
Re: howto clean disks ?
Shane J Pearson wrote: Hi Anthony, On 01/06/2005, at 4:01 PM, Anthony Roberts wrote: The 'dd' way is good enough unless someone is willing to to tear the drive apart in a lab. I think this depends on how you use dd though. If you just do a single pass of zeroes, but fear someone will mount a multi million dollar electron microscope forensic analysis, then yeah, that might not be enough. But write from /dev/urandom with dd multiple times to the disk and you should be okay even with that extreme case. If I were worried about open-drive analysis of the drive I want to clean, then I'd be physically destroying the drive also. Put it in a kiln, get the oxy torch into it, etc. If loading the drives with a single pass of zeros isn't good enough for your application, forget /dev/urandom or multiple passes or any other technique, and just physically destroy the drive. If you are really concerned someone might extract data after a zeroing of the drive, handing the drive over to anyone else in usable form is just silly. A while back, I modified an OpenBSD boot CD so it would do exactly this -- upon boot, it would dd /dev/zero over the first two wd devices, and the first two sd devices. No prompt, no warning, nothing. Boot the disk, kiss your data goodbye. It was designed to quickly and reasonably securely render the data on a bunch of old computers inaccessable with minimal intervention, before removing them from the donator's office. All the tools are on the boot CDs (and floppies) already. It turned out that when doing 4G IDE drives, I could have about four machines wiping at the same time in a non-ideal setting, by the time the fourth one was started, the first one was done. I labeled it in big, scary print, and try to keep track of where it is. So far, it has only claimed one innocent system by accident (Hey, why is this machine booting OpenBSD...Oh sh*t..dang, too late) Nick.
Re: howto clean disks ?
On Wednesday 01 June 2005 03:28 am, Matt Phillips wrote: If you are truly paranoid use DBAN, which is short for Darin's Boot and Nuke. IMO it is the best disk wiping tool out there. It gives you a couple different wiping methods to choose from, including the one used by the US DoD. You can also specify how many passes it makes. I'm sick of people passing on this US DoD standard as a fact. The true US DoD standard states that it DOES NOT make the drive safe for reuse unless it will be used to store data of equal or greater security rating. If the drive is no longer useful, after running this wipe the drive platters are destroyed. According to the website, DBAN is used by the US Dept of Energy and the National Nuclear Security Administration, which ain't bad. It may be, before the drives are reused internally for an equally or more secure project. Or just before the get thrown into the incinerator. Tim Donahue
Re: howto clean disks ?
On Wed, 1 Jun 2005, Anthony Roberts wrote: The 'dd' way is good enough unless someone is willing to to tear the drive apart in a lab. Items required for sure fire disk cleaning methodology. qty. 1 hard drive to clean qty. 1 high velocity military rifle I usually use a .223 round, but other parts of the world may prefer .308(7.62x51) or 7.62x54. qty. what number of rounds you feel like of previously described firearm place drive in front of dirt embankment position yourself ~100'/30M (you want to get some practice in don't you?)from the target, hrrrm, drive. begin target practice, hrrrm, drive cleaning, until drive is thoroughly destroyed, hrrrm, cleaned. retrieve spent brass ( you do reload don't you?), hrrrm, drive cleaning materials (this next step is optional depending on how environmentally conscious you are) pick up remains of target, hrrrm, cleaned hard drive and dispose of properly. remember, always thoroughly clean your firearm, hrrrm, drive cleaning tool after use. there, that should do it diana
Re: howto clean disks ?
On Wednesday 01 June 2005 08:06 am, Johan P. Lindstrvm wrote: The military (at least in Sweden) bakes a Trotyl / Pentyl cake with the drives as stuffing, don't know if that would change the magnetic properties but most likely make the process of collecting/organizing the pieces of the same drive quite labourious. I read an article on encasing your drives with Magnesium and Aluminium-Oxide and hook it up to the power supply through some programmable circut to remotely melt your drives, this would create a plasma at some 3000+ Celcius. Cant seem to find it again though... http://en.wikipedia.org/wiki/Plasma http://en.wikipedia.org/wiki/Exothermic_reaction You are might be thinking about using something like thermite. (Please note that thermite is dangerous stuff to play with because it does reach around 3000 C.) An oxy-acetyleme torch would be just as effective and a whole lot safer. http://en.wikipedia.org/wiki/Thermite Tim Donahue
Re: howto clean disks ?
Thanks Tim!, that was the link I was grepping for at wikipedia, my memory seems to be good but short... =) On 6/1/05, Timothy Donahue [EMAIL PROTECTED] wrote: On Wednesday 01 June 2005 08:06 am, Johan P. Lindstrvm wrote: The military (at least in Sweden) bakes a Trotyl / Pentyl cake with the drives as stuffing, don't know if that would change the magnetic properties but most likely make the process of collecting/organizing the pieces of the same drive quite labourious. I read an article on encasing your drives with Magnesium and Aluminium-Oxide and hook it up to the power supply through some programmable circut to remotely melt your drives, this would create a plasma at some 3000+ Celcius. Cant seem to find it again though... http://en.wikipedia.org/wiki/Plasma http://en.wikipedia.org/wiki/Exothermic_reaction You are might be thinking about using something like thermite. (Please note that thermite is dangerous stuff to play with because it does reach around 3000 C.) An oxy-acetyleme torch would be just as effective and a whole lot safer. http://en.wikipedia.org/wiki/Thermite Tim Donahue
Re: howto clean disks ?
Once information on a digital media has been overwritten, it cannot be recreated/restored in any lab. All this talk about electron microscopes and overwriting in multiple passes is just a load of crap derived from an old DoD standard. It has no practical meaning. One overwrite is enough. Please let this ugly rumour die :) That is not the case. On magnetic drives, the field can spread beyond the region written to by the drive heads, and can be read by a suitably equipped lab. Reports on how effective this is and what methods can be used to destroy the data vary, but it's safe (or rather, it's necessary) to assume intelligence agencies or big companies can do stuff we don't know about. Besides, drives can transparently reassign sectors that go bad, and no mere dd can get to those. If 'they' can take apart the drive or get suitable firmware for it, they can certainly read all the sectors. Even if you assume overwritten data can not be recovered, you would still need to wipe these sectors. On 6/1/05, Diana Eichert [EMAIL PROTECTED] wrote: place drive in front of dirt embankment position yourself ~100'/30M (you want to get some practice in don't you?)from the target, hrrrm, drive. begin target practice, hrrrm, drive cleaning, until drive is thoroughly destroyed, hrrrm, cleaned. retrieve spent brass ( you do reload don't you?), hrrrm, drive cleaning materials Rendering the drive media unreadable to a standard drive won't necessarily render it unreadable to determined forensic annalysis. It requires high temperatures. If you have information valuable enough to spend that kind of money to recover, then the cost of losing the use of a drive is trivial. I don't advocate thermite or an oxy torch to prevent 'them' from getting their hands on my MP3 collection. I wouldn't take the trouble to destroy any of my hard drives because I don't have anything worth spending that kind of money to recover.
Re: howto clean disks ?
On Wed, 1 Jun 2005, Dennis Lindahl wrote: Once information on a digital media has been overwritten, it cannot be recreated/restored in any lab. All this talk about electron microscopes and overwriting in multiple passes is just a load of crap derived from an old DoD standard. It has no practical meaning. One overwrite is enough. Please let this ugly rumour die :) / Dennis I like my method better. ;-) diana
Re: howto clean disks ?
why don't you try pissing on it. I can gurantee that everyone will forget about reclaiming your super-secret data.Ever. If you are overly-paranoid, as any OBSD user should be, you can try the heavier solution which is definitely the(...)
Re: howto clean disks ?
Diana Eichert wrote: On Wed, 1 Jun 2005, Anthony Roberts wrote: The 'dd' way is good enough unless someone is willing to to tear the drive apart in a lab. Items required for sure fire disk cleaning methodology. qty. 1 hard drive to clean qty. 1 high velocity military rifle I usually use a .223 round, but other parts of the world may prefer .308(7.62x51) or 7.62x54. qty. what number of rounds you feel like of previously described firearm place drive in front of dirt embankment position yourself ~100'/30M (you want to get some practice in don't you?)from the target, hrrrm, drive. begin target practice, hrrrm, drive cleaning, until drive is thoroughly destroyed, hrrrm, cleaned. retrieve spent brass ( you do reload don't you?), hrrrm, drive cleaning materials (this next step is optional depending on how environmentally conscious you are) pick up remains of target, hrrrm, cleaned hard drive and dispose of properly. remember, always thoroughly clean your firearm, hrrrm, drive cleaning tool after use. there, that should do it diana Nick, I'm beginning to think the addition to the FAQ archived at http://marc.theaimsgroup.com/?l=openbsd-miscm=106302607626276w=2 might be a good idea. Though I have to admit, Diana has a very interesting (and probably very fun) alternative :)
Re: howto clean disks ?
That is not the case. On magnetic drives, the field can spread beyond the region written to by the drive heads, and can be read by a suitably equipped lab. Reports on how effective this is and what methods can be used to destroy the data vary, but it's safe (or rather, it's necessary) to assume intelligence agencies or big companies can do stuff we don't know about. Besides, drives can transparently reassign sectors that go bad, and no mere dd can get to those. If 'they' can take apart the drive or get suitable firmware for it, they can certainly read all the sectors. Even if you assume overwritten data can not be recovered, you would still need to wipe these sectors. Like I said, once the information _has_ been overwritten, it cannot be recovered in any lab. A fellow from IBAS said this during a seminar I attended recently. He even said it was a fundamental principle for all professional data recovery. If it had been possible to retrieve overwritten data from harddisks, im pretty sure the technique would have been used in some high profile criminal investigation. But it hasnt, because it is a myth. And like you said, there are indeed issues to actually performing a complete overwrite. / Dennis
Re: howto clean disks ?
On Thu, 2 Jun 2005, Dennis Lindahl wrote: SNIP Like I said, once the information _has_ been overwritten, it cannot be recovered in any lab. A fellow from IBAS said this during a seminar I attended recently. He even said it was a fundamental principle for all professional data recovery. If it had been possible to retrieve overwritten data from harddisks, im pretty sure the technique would have been used in some high profile criminal investigation. But it hasnt, because it is a myth. And like you said, there are indeed issues to actually performing a complete overwrite. / Dennis Let me 'splain something to you in PLAIN English. The US Gov't is WILLING to RELEASE and NOT PROSECUTE spies if it appears that CLASSIFIED information COULD be compromised in a court trial, NOT will be compromised, just the CHANCE of it occurring. Therefore just because YOU haven't heard of a way to recover over written data doesn't mean it can't be done. FWIW I don't personally know of a way to recover over written media, what I can say is that media is physically destroyed at various facilities I've worked at. diana
Re: howto clean disks ?
On 6/1/05, Diana Eichert [EMAIL PROTECTED] wrote: On Thu, 2 Jun 2005, Dennis Lindahl wrote: SNIP Like I said, once the information _has_ been overwritten, it cannot be recovered in any lab. A fellow from IBAS said this during a seminar I attended recently. He even said it was a fundamental principle for all professional data recovery. If it had been possible to retrieve overwritten data from harddisks, im pretty sure the technique would have been used in some high profile criminal investigation. But it hasnt, because it is a myth. And like you said, there are indeed issues to actually performing a complete overwrite. / Dennis Let me 'splain something to you in PLAIN English. The US Gov't is WILLING to RELEASE and NOT PROSECUTE spies if it appears that CLASSIFIED information COULD be compromised in a court trial, NOT will be compromised, just the CHANCE of it occurring. Therefore just because YOU haven't heard of a way to recover over written data doesn't mean it can't be done. FWIW I don't personally know of a way to recover over written media, what I can say is that media is physically destroyed at various facilities I've worked at. diana From my understanding of it, the values stored on your harddrive are not exactly one's and zeros. As long as the magnetic field is close to zero, like .15 gauss (or whatever the unit would be), it is treated like a zero. If it is close to a one (like .83 gauss, again I'm not sure what the value or unit would actually look like) it will be regarded as a one. By analyzing these true values of the magnetic field, professionals can infer what that particular bit used to be.
Re: howto clean disks ?
Hi Dennis, Quoting Dennis Lindahl [EMAIL PROTECTED]: Once information on a digital media has been overwritten, it cannot be recreated/restored in any lab. All this talk about electron microscopes and overwriting in multiple passes is just a load of crap derived from an old DoD standard. It has no practical meaning. One overwrite is enough. Please let this ugly rumour die :) You seem a little quick to discount something as impossible. Do you think Military choose physical destruction for the heck of it? IBAS can't do it on the cheap, so they claim it impossible? And you take that as gospel? The nature of digital signals comes down to thresholds. The actual analog values are not absolutely digital and remnants often remain. When you open up a storage device and circumvent the part which enforces and interprets the thresholds which define what constitutes a one or a zero, you then have the ability to see the remnants without the masking effect of those digital parts. If only zeroes where witten to the disk, these remnants stand out and make it easier to reconstruct the original data. By overwritting with ones, zeroes (or an alternating pattern of ones and zeroes) and then random data, the remnants become lost in a sea of noise. http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html It comes down to cost/benefit. The fact that you don't hear about it much is because it is costly and time consuming. Just because you can't do it at home, does not mean it can't be done. Shane J Pearson This email was sent from Netspace Webmail: http://www.netspace.net.au
Re: howto clean disks ?
Once information on a digital media has been overwritten, it cannot be recreated/restored in any lab. All this talk about electron microscopes and overwriting in multiple passes is just a load of crap derived from an old DoD standard. It has no practical meaning. One overwrite is enough. Please let this ugly rumour die :) Peter Gutman presented a paper on the technique of using electron microscopes to recover data from overwritten disks nearly 10 years ago at a USENIX Security Symposium. Peter did the research on this while at IBM's Watson Laboratory. Yes, it's very expensive (in terms of time) and you need sophisticated equipment but it is well within the reach of any technical university or well financed organisation. Like all security decisions how you wipe your data depends on how valuable it is. For most stuff one pass is probably enough but OTOH doing a five or seven pass with random data is not a large incremental cost so why not do it properly. The biggest cost in the exercise is the time it takes to boot the machine up on a CD with the right tools and start them running. Do you really care if it takes one or five hours to do the wipe. (OK there will be times when you do care and in that case you opt for speed unless there is something extraordinarily sensitive on the disk...) Russell [demime 1.01d removed an attachment of type application/x-pkcs7-signature which had a name of smime.p7s]
Re: howto clean disks ?
Ed White wrote: Hi, I'm going to give away some old hard disks and I'm planning to delete/overwrite all the data on them. Is there any tool to make this automagically ? Thanks. dd if=/dev/zero of=DEVICE_you_want_to_erase -- Adam Papai Digital Influence Inc. E-mail: [EMAIL PROTECTED] Phone: +36 30 33-55-735
Re: howto clean disks ?
On Wed, 1 Jun 2005 07:36:22 +0200, Ed White wrote: Hi, I'm going to give away some old hard disks and I'm planning to delete/overwrite all the data on them. Is there any tool to make this automagically ? Thanks. dd From the land down under: Australia. Do we look umop apisdn from up over? Do NOT CC me - I am subscribed to the list. Replies to the sender address will fail except from the list-server.
