Complete HDD erasing

[Alseimik]

Hey guys, i'm going to buy a new computer, so i want to erase everything from my old 80 gb HDD... its unusable these days with that little amount of space

I read somewhere that some scientist claimed that 45 times of overwriting would kill any trace. So that's what I want, maybe more.

I found the software "Active Killdisk" mostly because of the dos program which was with it. But the freeware version only supported one single overwrite, and only with zero's. which is far from the 45 times with random data that i wanted...

Do you know of anything better? To buy the killdisk in only dos version, would cost me 50 fucking dollard!!! - Not an option

[PhoenixEnigma]

Darik's Boot and Nuke should do the trick. Really, though, a single overwrite with random data is enough to stop pretty much anyone outside of dedicated intelligence circles from recovering your data - and if that's actually a concern, you'd be better served with an oxy-acetylene torch anyways.

[Stev]

Just boot a linux distro (you can boot live from a cd or from an usb disk) and then run this as root:

Code: Select all

dd if=/dev/urandom of=/dev/sdXY


Where sdXY is the partition you want to erase. If you aren't familiar with Linux just ask and I'll help you finding the right partition.

The above command will fill your partition with random data. You could also fill your entire disk if you want.

Edit: Obviously this will take a while.

[PM 2Ring]

I don't understand why you want to do this. But I suggest reformatting the disk to use a non-journaling filesystem, eg FAT32, then run shred on it.
http://unixhelp.ed.ac.uk/CGI/man-cgi?shred+1

Overwrite the specified FILE(s) repeatedly, in order to make it harder for even very expensive hardware probing to recover the data.

A single invocation of shred can overwrite a file with random bytes as many times as you like. You can even tell it to do a final pass of zeroes to (sort of) hide the evidence of shredding.

Also visit Wikipedia to see the latest wisdom on this topic.

Edit: Ninja'd by Stev. But shred is still cool.

[shieldforyoureyes]

The "45 overwrites" claim is completely useless out of context. The recoverability of erased data on hard drives changes with every technological development. Two overwrites on anything from the past ten years will stop anyone outside the NSA. Unless you're a spy or a major politician, that will suffice.

If you really care that much, destroy the drive. That's still the way the US military deals with drives that have had classified data on them. (You'll see references in places to "DOD Standard Erase Procedure" or something like that. That's kind of misleading, in that it isn't sufficient to call a drive that once had classified data on it unclassified.)

[hintss]

wasn't there that program on MaximumPC's top ten freeware apps called copywipe or something similar?

[poxic]

In a similar vein... a friend gave me her 7-to-10 year old computer to recycle and wipe the hard drive. It doesn't have a USB port. It has a 3.5 floppy, but my current PC doesn't. Her old box is Linux, so it won't talk to my new-ish LCD screen (we tried. It booted fine, then gave us "unsupported video mode" or something after the boot sequence).

I don't have access to acetylene torches, nor accelerator-sized magnets. I could pay someone to wipe the drive for me, but I'd rather not. I'll crack open my new(ish) PC case to plug this in as a slave drive if I have to, but there's probably something I can beg/borrow/buy along the lines of a USB connector for old IDE drives, no?

[PhoenixEnigma]

In a similar vein... a friend gave me her 7-to-10 year old computer to recycle and wipe the hard drive. It doesn't have a USB port. It has a 3.5 floppy, but my current PC doesn't. Her old box is Linux, so it won't talk to my new-ish LCD screen (we tried. It booted fine, then gave us "unsupported video mode" or something after the boot sequence).

I don't have access to acetylene torches, nor accelerator-sized magnets. I could pay someone to wipe the drive for me, but I'd rather not. I'll crack open my new(ish) PC case to plug this in as a slave drive if I have to, but there's probably something I can beg/borrow/buy along the lines of a USB connector for old IDE drives, no?

Lots of such devices exist. You could toss it in an external enclosure (cheapest on Newegg Canada looks to be this one, might be able to find cheaper yet at your local geek hut), or get an actual IDE to USB adapter like this (although I haven't heard particularly great things about such adapters.)

[hintss]

get torx drivers, disassemble drive. remove platters. get greasy fingerprints all over them. then make that one windchime on instructables or somewhere.

alternative

disassemble drive, hit platters with hammer.

alternative alternative

disassemble drive, fingerprints, then that one neat clock that was on hackaday. they punched holes in the platter!

[PM 2Ring]

In a similar vein... a friend gave me her 7-to-10 year old computer to recycle and wipe the hard drive. It doesn't have a USB port. It has a 3.5 floppy, but my current PC doesn't. Her old box is Linux, so it won't talk to my new-ish LCD screen (we tried. It booted fine, then gave us "unsupported video mode" or something after the boot sequence).

Does the old computer have a CD drive? If not, I guess it must be a pretty ancient Linux distro that was loaded from floppies.

The USB to IDE interface sounds like a good idea. There's probably no point putting in a simple USB card, as the BIOS won't know how to boot from a USB stick, although there are ways around that if you have a boot floppy. I'm sure that some one here that lives on the same continent as you could post you a Linux boot floppy if you want to try that method.

disassemble drive, hit platters with hammer.

No! They make excellent mirrors that don't break when you drop them. I've been using one as a shaving mirror for several years.

And if you're disassembling HDs, don't forget to scavange the supermagnets from them. They're great fun to play with if you're careful, but they do tend to shatter if they attract each other from more than a couple of centimetres.

[hintss]

but you could just get fingerprints all over them, then make that one clock on hackaday or that one windchime...

which reminds me, I have an old 2GB HDD, that works. Windows 98.

I also have a spare 250GB, broken. AFAIK, 2 platters, WD.

[WarDaft]

Toss it in a Kiln.

[hintss]

would microwave work with just the platters in?

[phillipsjk]

Only if you want to destroy the microwave. You are probably thinking of CDs. Even then, you should have a cup of water in there as a load to absorb stray microwaves.

[hintss]

yeah, I was, but my logic is that if the reason CDs do that is because they have metal, and HDDs store data magnetically, then they must have metal in the platters, so it must do the same. Am I right?

[Carnildo]

No. Hard-drive platters may not actually have any metal in them. One of the popular ways of making platters is a metal oxide (nonconductive) on a glass substrate (nonconductive). The only thing putting one of those in the microwave will do is wreck the spindle, and that won't do anything to the data.

[phillipsjk]

Actually, that would make hard-drive platters easier to destroy in the microwave. A metal disk in the microwave would be relatively inert: the microwave oven is a metal box after all.

Consider CDs: the only metal in them is the data layer; the rest is plastic.

[Carnildo]

Actually, that would make hard-drive platters easier to destroy in the microwave. A metal disk in the microwave would be relatively inert: the microwave oven is a metal box after all.

Consider CDs: the only metal in them is the data layer; the rest is plastic.

Metal oxide is not metal. It has none of the properties of metal. Thinking of it as metal will only give you wrong answers.

[hintss]

Actually, that would make hard-drive platters easier to destroy in the microwave. A metal disk in the microwave would be relatively inert: the microwave oven is a metal box after all.

Consider CDs: the only metal in them is the data layer; the rest is plastic.

Metal oxide is not metal. It has none of the properties of metal. Thinking of it as metal will only give you wrong answers.

its ferrous? apparently so...

[cogman]

Just boot a linux distro (you can boot live from a cd or from an usb disk) and then run this as root:

Code: Select all

dd if=/dev/urandom of=/dev/sdXY


Where sdXY is the partition you want to erase. If you aren't familiar with Linux just ask and I'll help you finding the right partition.

The above command will fill your partition with random data. You could also fill your entire disk if you want.

Edit: Obviously this will take a while.

This is the best answer so far. Do it once, and pretty much nobody will be able to get anything off of it. Do it twice, and most professionals won't be able to recover anything. Do it 3+ times, and you have something that can't be recovered.

[phillipsjk]

Only if you want to destroy the microwave. You are probably thinking of CDs. Even then, you should have a cup of water in there as a load to absorb stray microwaves.

Update: putting a "load" in the microwave not only protects the mircowave oven; it protects the CD you are trying to fry too!

I did not check for data degradation though (tested on a failed burn).

[Bobber]

Only if you want to destroy the microwave. You are probably thinking of CDs. Even then, you should have a cup of water in there as a load to absorb stray microwaves.

Update: putting a "load" in the microwave not only protects the mircowave oven; it protects the CD you are trying to fry too!

I did not check for data degradation though (tested on a failed burn).

You lied to me. I used a glass of water instead of a cup of water though. Maybe it is the cup, and not the water, which protects the CD!
The picture is after a ~1.2 second exposure to 750 watts.
Naturally, this CD was my first choice for this experiment.

[Oregonaut]

Seriously, there is no reason to go to such advanced methods.

Use.
A.
Hammer.

Seriously, the pixie dust that comes out after one whack of a 3 gauge rubber mallet is actually very pretty.

And I know for sure and certain that you are not getting anything off that drive anymore.

[sje46]

Yeah, but with a hammer, you can't turn your HDD into a cheap DIY speaker anymore.

[hintss]

also, hammer wouldn't really be considered erasing...

[phillipsjk]

You lied to me. I used a glass of water instead of a cup of water though. Maybe it is the cup, and not the water, which protects the CD!
The picture is after a ~1.2 second exposure to 750 watts.

Okay, I was able to reproduce your results after ~6 seconds at 1100Watts using the same a similar cup of water.

The first time, I put the CD, Label side up directly in the center of the microwave. I then put the (pyrex) mug (full of about 250mL of water) directly on top of the CD (as if it was a coaster). After 1 minute, the cup of water was hot, but the CD was still intact.

The second time, I put both objects on opposite sides of the turn-table. Edit: the scorch marks on my CD look slightly asymmetric: I think the side closer to the water did not burn as badly.

[hintss]

I'm not sure why would you really need to do that, but anyway - there are 2 ways to destroy your hard-drive. First, software-based, and second - physical. For the first method I have to mention - there's no such soft wich will allow you to completely and irrevocably erase your data. Modern hard-drives are recoverable even after you jump on them. So, nullification of your drive is a systematic task, and you can use software as Acronis, MHDD, and others. For the second method, physical, there's a special device, called Hard Disk Crusher. It perforates holes in your hdd, making it unreadable.

I'd say that the larger bits would have proabably been recoverable, though in the google search, just as many degaussers came up as crushers, so why not use a degausser?

[phillipsjk]

there's no such soft wich will allow you to completely and irrevocably erase your data.

[Citation Needed]

The goal of a hard-disk is to store data as densely and reliably as possible. As density has improved, forward error correction and fancy modulation schemes are used to help pull your data out of the noise. Yes, modern drives will silently reallocate sectors, but I like to think that is the exception rather than the rule.

Even if your assume an NSA (or Chinese) back-door is installed in every factory drive-wipe routine, it is still possible to securely erase the drive:

1. Record the size of the drive (new) in sectors.
2. Overwrite entire drive with incompressible data such as /dev/urandom or the encrypted version of the Avatar Blu-Ray disk, etc.
3. Read back the incompressible data to be sure it was written correctly. Verify drive size. This should prove all of the accessible space is overwritten.
4. If you are paranoid, power cycle and repeat steps 2 and 3. This should prove any hidden space is overwritten unless: (a) hidden space does not store data. (b) data is only stored in the hidden space when spyware with knowledge of the hidden space is activated; implying /dev/urandom can't overwrite the hidden space because the spyware is not runnning.
5. If you need plausible deniability, (or are concerned about any copyright infringement), overwrite with zeros. Again verify successful write and drive size.

Solid-state drives allow your information to be read by an electron microscope again though. The electron tunneling for storing information in flash memory degrades the (floating) gate insulation on the transistor storing the information. However, Inverting the bits probably won't work because of wear-leveling silently moving your data around. Overwriting at least twice with random data should make recovery difficult.

[Bobber]

You lied to me. I used a glass of water instead of a cup of water though. Maybe it is the cup, and not the water, which protects the CD!
The picture is after a ~1.2 second exposure to 750 watts.

Okay, I was able to reproduce your results after ~6 seconds at 1100Watts using the same a similar cup of water.

The first time, I put the CD, Label side up directly in the center of the microwave. I then put the (pyrex) mug (full of about 250mL of water) directly on top of the CD (as if it was a coaster). After 1 minute, the cup of water was hot, but the CD was still intact.

The second time, I put both objects on opposite sides of the turn-table. Edit: the scorch marks on my CD look slightly asymmetric: I think the side closer to the water did not burn as badly.

Oh, awesome. As you see, my CD is also burnt asymmetrically, and since I did put the water next to it in the microwave (it doesn't have a turn-table), it seems likely that the unharmed side of my CD was close to the glass of water. I had around 300 ml in there in a normal soda-lime glass drinking glass. My CD was also label-side up.

[Oregonaut]

also, hammer wouldn't really be considered erasing...

That depends, are you using the term in the CIA or the OED sense?

I thought the goal was to make sure no one could get a hold of the data on the drive. My method, I feel, is the most certain.

[phillipsjk]

My definition of erasing for hard-drives is "overwriting with a specific data pattern."

That pattern can be zeroes, "DOD erased xxxxxxxxxxxxxxxxxxxxx June 9, 2010", blank filesystem image, an encrypted DVD image, or a pseudorandom number generator.

A hammer cannot erase the drive according to my definition. However, a hammer can cause irreversible media destruction (that software methods can not). I am not sure how important that distinction is

[hintss]

idea: open up the drive, trick it into spinning up continuously, then gently tap the head onto different parts of the platter, scratching it.

[Dason]

idea: open up the drive, trick it into spinning up continuously, then gently tap the head onto different parts of the platter, scratching it.

This just seems like a complicated way of saying scratch it.

[Sizik]

Thermite.

[Bobber]

I've heard of mass torrenters building devices controlled by software that can be activated by a password to ignite a stash of thermite inside the computer, above the hard drives, in case the police would want to take the computer for a search.

I wish I could remember where I read this.

[GU3RNICA]

I've heard of mass torrenters building devices controlled by software that can be activated by a password to ignite a stash of thermite inside the computer, above the hard drives, in case the police would want to take the computer for a search.

I wish I could remember where I read this.

I've heard people doing the same except the password is received via a phone call...

Seems they setup entire interfaces(like phone banking) to control their kit with a simple phone call and with a panic command that initiates the thermite.

Always wanted to set something like that up (without the thermite).

[hintss]

arduino?

[phillipsjk]

Something safer than thermite would be to keep the drives(s) encrypted (full drive encryption) using a stupidly long passphrase kept in a safety deposit box.

Delete the key from memory when the signal is received or a case intrusion is detected. While you are being paranoid, don't install any IEEE1394 (Firewire) ports. Disable automounting/autorun (read: USB drives) as well.

Any warrant the police serve you with will probably prohibit you from tampering with evidence. However, I can just about guarantee they won't ask you how to properly shutdown you computer without tampering with evidence: they won't trust you, and you are unlikely to be an expert in the field of forensics. You can have the machine set up to wipe the encryption keys from memory if they even try to mount a USB drive. BTW, police will be able to get a warrant for the safety deposit box if they know about it.

Just a minute, there is a knock at my door...

[hintss]

Something safer than thermite would be to keep the drives(s) encrypted (full drive encryption) using a stupidly long passphrase kept in a safety deposit box.

Delete the key from memory when the signal is received or a case intrusion is detected. While you are being paranoid, don't install any IEEE1394 (Firewire) ports. Disable automounting/autorun (read: USB drives) as well.

Any warrant the police serve you with will probably prohibit you from tampering with evidence. However, I can just about guarantee they won't ask you how to properly shutdown you computer without tampering with evidence: they won't trust you, and you are unlikely to be an expert in the field of forensics. You can have the machine set up to wipe the encryption keys from memory if they even try to mount a USB drive. BTW, police will be able to get a warrant for the safety deposit box if they know about it.

Just a minute, there is a knock at my door...

well, just to put this out there, my new password on google and this netbook is 53 characters long.

[phillipsjk]

I was thinking something at least 2000 characters long, possibly in the form of a letter that would have a plausible reason for being in the safety deposit box

"passphrases" are different from "passwords" in that your don't type them in very often. Unlike passwords, they are always written down. When I had my Wifi Access point set-up, I was using an md5 hash of a file that changes over time: even if I lost it, I can just generate a new one.

If has been theorized that such passwords (including your 53 character password if truly random) cannot be solved by brute force (unless you consider the $5 wrench brute force).