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Paranoia and deletion: the wipe man page
- Mithrandir 16y agoThe man page is correct about quite a few things, but it's also a bit sarcastic: The best way to sanitize a storage medium is to subject it to tempera- tures exceeding 1500K. As a cheap alternative, you might use wipe at your own risk. Be aware that it is very difficult to assess whether running wipe on a given file will actually wipe it -- it depends on an awful lot of factors, such as : the type of file system the file resides on (in particular, whether the file system is a journaling one or not), the type of storage medium used, and the least significant bit of the phase of the moon. But no matter what, wipe is a really great program.
- Jach 16y agoFunny, I was just having a conversation today with a friend who works for the company selling http://www.whitecanyon.com/wipedrive-erase-hard-drive.php http://www.whitecanyon.com/wipedrive-erase-hard-drive.php and remarking that it may keep your data safe from identity thieves, it wouldn't protect you from the FBI.
- MikeCapone 16y agoDid he explain more specifically why he thinks it would "protect you from the FBI"?
- DanI-S 16y agoThe idea that they need actual evidence to lock you up is so 20th century...
- MikeCapone 16y ago*I can't edit my previous message anymore, but the "would" should read as "wouldn't".
- srean 16y agoAn alternative could be to overwrite the disk with null bytes. dd if=/dev/zero of=/dev/hda bs=1M Wonder if it is going to be slower than wipe.
- ComputerGuru 16y ago....multiple times. Overwriting it once prevents software reconstruction of the data, but magnetic analysis of the underlying disk itself can reveal (depending on the voltage returned by the resulting 0 or 1) whether the previous value was (within a degree of certainty) a 0 or 1.
- srean 16y agoAh good point +1. Did not think about that. Maybe a single pass from /dev/urandom will suffice. But its going to be slow.
- deleted 16y ago[deleted]
- nodata 16y agoWait - how automated is magnetic analysis? How much would it cost to recover a gigabyte disk, for example? What about non-spinning disks, are they cheaper or more expensive?
- ComputerGuru 16y agoIt's expensive as hell :) The companies that do it charge several thousand an hour, IIRC. (this was back in the 90s?) Depending on the non-spinning disk type in question, it can be either more or less secure than the usual magnetic HDD. You've got "flash" but that's just a nice word for any number of highly-differing technologies such as MLC and SLC on the inside. And you have NAND vs NOR techs to consider as well. Perhaps the security in non-magnetic-HDDs comes from the fact that they're so new to the table, not many specialize in restoring data from them.
- ck2 16y agoI always dissemble my old hard drives, it's therapeutic somehow. I am not sure how they broke that disc into so many pieces though, in my experience they are incredibly strong and rigid. The discs make great wind chimes too. Harbor Freight has a $3 security bit set if you have drives with special screws.
- InclinedPlane 16y agoLiquid nitrogen?
- ck2 16y agoI looked it up on flickr http://www.flickr.com/photos/jon_a_ross/1482849745/ http://www.flickr.com/photos/jon_a_ross/1482849745/ and from the caption it sounds like it actually did that to itself which seems impossible unless maybe the platter was made defectively in the first place ... ? (note it was an "old" 40gb drive - also looks like 2.5 inch)
- wazoox 16y agoSome drives have glass platters AFAIK. This would explain how this one was broken.
- hnhg 16y agoSorry to be a pedant, but I think you mean "disassemble" - I always get the two mixed up too.
- ronnoch 16y agoCurrently your comment, which adds nothing to the discussion except a simple spelling correction, has more upvotes than the parent. Sign of the times for HN? Not to say spelling corrections are never useful, I think they often are, but I don't understand the mindset that upvotes them over comments that actually participate in the discussion.
- idm 16y ago
- mmaunder 16y agoI sleep at night knowing that the teams of highly effective government data recovery personnel that Hollywood portrays will never exist.
- chanux 16y agoAny idea what's the difference between wipe and shred?
- naner 16y agoThe shred man page warns you that the tool is not fully effective on journaled filesystems. I doubt wipe is, either.
- Entlin 16y agoTo everybody spending thought on this: Relax, nobody is interested in your porn collection.
- haribilalic 16y agoI've used such tools to wipe my hard drives before selling or donating used computers (although I would use them before disposing of a hard drive in any way, really). I have heard of people buying up used computers and hard drives and extracting saved passwords from them. A lot of people are smart enough to format it quickly, but not everyone will let (or know to) a computer sit for dozens of hours so that things might be wiped more securely.
- halfasleep 16y agoI generally recommend DBAN[1] for people who are disposing of old boxes. [1]http://www.dban.org/ http://www.dban.org/
- jws 16y agoI've had the experience where people agree to buy my broken computers for parts and the deal is done, until I mention that the "drives are wiped and ready to go". Then I never hear from them again. Granted, somehow visiting the craigslist site turns ordinary people into flakes, but the "wiped" statement correlates a bit too well with the vanishing interest.
- evgeny0 16y ago+1, but I'd stop mentioning it after the first time (unless of course you're just doing this as an experiment and aren't really interested in selling the stuff)
- fdhjtyjkty 16y ago●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------● ●------ http://u.ly/73I http://u.ly/73I ------●
- troels 16y agoOf course this shifts the trust to the computing system, the CPU, and so on. I guess there are also "traps" in the CPU and, in fact, in every sufficiently advanced mass- marketed chip. Wealthy nations can find those. Therefore these are mainly used for criminal investigation and "control of public dissent". I'm unsure in which way a government agency could benefit from having backdoors in the CPU? Even if they did, and even if it could detect that some sort of encryption was going on, where would it store the interesting data?
- sesqu 16y agoWell, there was/is that trusted computing thing, i.e. putting DRM on the PC in hardware. The benefit would be denying encryption from terrorists/pirates/dissenters, like he just said. Interesting data can be stored just about anywhere, from phoning home to hidden partitions to having a small flash on the BIOS, depending on what's deemed interesting (logs, sector addresses, cryptographic keys, painted files).
- hexley 16y agoFor those on Mac OS X (and perhaps *BSD?), we have srm. The Secure Empty Trash function is a frontend for this IIRC.
- stcredzero 16y agoI wish there was a version that only overwrite once with 1's. That would be best for my SSD. (Which has wear leveling and is formatted with a journalling filesystem anyhow, so perhaps it's moot.)
- suraj 16y agoHow would a hard disk controller detect encrypted data? It is essentially a (psudo-) random stream of bytes. Even if the controller is programmed to recognize such streams, it would be easy to first wipe disk by writing small random files all over and then wiping with 0/1 pattern. So any cached data is essentially worthless.
- endian 16y agoDoes anyone know if any such FOSS works with SSDs and their wear-levelling of their writes?
- tedunangst 16y agowipe is rather unlikely to overwrite the bits on an SSD. Even with TRIM (which wipe won't use, btw), the disk will prefer using a blank sector to one it has to erase. Reading the currently unmapped spare sectors is probably something anyone with a solder gun can do.
- Confusion 16y agoSilly conspiracy theory. 1) The scope is too large. Too many engineers at hard drive manufacturing companies would have to know about it. 2) Too America-centric. Engineers in foreign countries, that actually build most of the stuff, would know about it. It would be an enormous security gap that they could use as well. The sad thing is that such paranoid fantasies, that are easy to debunk, blind you to the actual conspiracies, that are less comprehensive, more subtle and therefore much more threatening. I bet the TLA government agencies love these stories.
- rapind 16y agoMaybe it's the gov who posits these theories?... nah.
- SoftwareMaven 16y agoThe invisible yellow dots identifying printers went a long time before becoming common knowledge. I don't believe TFA for an instance, but it doesn't seem an impossibility.
- SoftwareMaven 16y agoUgh, sometimes I wish I could edit later. Make that "I don't believe for an instant". I hate responding on my phone.
- coffeeaddicted 16y agoBut what to do against those brain-wave readers? I better start thinking encrypted!
- sp332 16y agoI'm sorry, but this info is nearly ten years out-of-date. First, the Gutmann method was designed for encodings back in the days of RLL/MFM encoded drives. For newer drives which really push the physics quite a lot further, two passes of random data are enough to throw the magnetic domains into a statistical dead heat. There just isn't any physical room on the drive to hold old data. Secondly, new drives reserve a percentage of the room (invisible to the user), in case some of the sectors go bad the controller will re-map them transparently to new sectors. This might leave old data in the old sectors, where you can't normally see it but an investigator armed with the proper ATA commands can. (This isn't a conspiracy of the government and drive manufacturers, it's all there in the ATA spec.) The correct way to securely erase a drive is to send the drive the SECURITY-ERASE command. The drive controller will securely erase every part of the drive. https://ata.wiki.kernel.org/index.php/ATA_Secure_Erase https://ata.wiki.kernel.org/index.php/ATA_Secure_Erase The NSA actually recommends this to other government agencies, so it's probably OK.
- jwr 16y agoBut how do you know if the data actually gets erased by the drive?
- mseebach 16y agoYou don't know, you hardly ever know anything. You evaluate the evidence (as laid out by the GP) and conclude that it's most likely the case. This is really the approach that most conspiracy theories take. The fact that we don't know something to be true (but it's very likely to be) is used as an implication that it's probably false.
- jerf 16y agoIf that possibility seriously concerns you, follow it up by physical destruction of the drive. Magnets strong enough to actually damage the data aren't a good cost/benefit from what I gather (too strong, too dangerous, too much hassle), so either shred or melt the drive platters. I'm generally satisfied with df if=/dev/zero of=/dev/sda because I'm not actually dealing with anything that sensitive, but if you are, just take appropriate steps. Defense in depth.
- deutronium 16y agoI love this section: "I strongly recommend to call wipe directly on the corresponding block device with the appropriate options. However THIS IS AN EXTREMELY DANGEROUS THING TO DO. Be sure to be sober."
- ams6110 16y agoI use DBAN to wipe hard drives before disposal. If you are replacing a failed drive, the only reasonable thing you can do is physically destroy the platters.
- cloudwalking 16y agoWhen I was younger, I erased a harddrive by covering it with burning thermite. It was pretty impressive, melting the drive, turning the sand underneath to glass, and burning through the asbestos pad into the cement.