Securely erase a harddrive?

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Baiting Guru Joined: 07 Jan 2007 Posts: 2922

Slightly off topic...but i'll ask anyway. Very Happy

I will be moving soon, and leaving my pc (win 98, very old) behind, i understand that the best way to clear the harddrive is to destroy it (literally) is there any other "100% risky free" way to ensure that it's clean.

I want to donate it to the thrift store, is it worth it without a hard drive? Is there anything else i can do with it, that won't involve it sitting in a landfill etc etc...

Posted: Mon Mar 26, 2007 7:47 pm

If you don't want to use a hammer, try this:

http://www.kremlinencrypt.com/securedelete.htm

There is a free evaluation version.

Quote:

Deleting a file by dragging it to the Trash (Mac OS) or Recycle Bin or typing 'del' at the command prompt (Windows) does not actually remove the contents of the file from your hard drive. Your operating systems simply flags it to be overwritten in the future. If there is little disk acscess, the contents of these files can remain, unchanged, on your hard drives for extremely long times and available to anyone with a low-level disk utility.

But when you drag your top-secret document to the Kremlin Secure Delete (Recycle Bin), it's just not flagged to be overwritten, it's gone forever. Kremlin overwrites your documents with a variation of the Department of Defense standard, writing zeros, ones, and a pseudo-random bit stream and its binary complement a user-specified number of times.

JMR, if you do get a new computer, you can set up your old hard drive as a 'slave', there are little jumpers at the back that let you set this. Your new HDD is the 'master'. You can now copy one to the other. I had to do this another time my PC died.

Posted: Mon Mar 26, 2007 10:01 pm

Regarding the HDD.
Why not just FDISK it?
Simple method to use is this

Use DELPART to delete all and any existing partitions.
Use FDISK to create new partitions (eg create two partitions on drive)
Format Partitions.
Use DELPART again to delete partitions

Now either FDISK and create new partition (if you are feeling helpful) or just leave unpartitioned.
Personally, I suggest creating a single partition and then leave un formatted. Also, I suggest NOT giving it to a charity shop, if you want to give it away to a charity, find one that will re-use it after THEY have cleared it to DOD standards.

Posted: Mon Mar 26, 2007 10:14 pm

^^^The problem is that information can still be recovered. There's shareware out there that will overwrite 7 times with one's and zero's. I've been told that gets it. I take the HDD out and then whack it will a hammer.
All the rest go to the thrift store.

Posted: Mon Mar 26, 2007 10:29 pm

^^^
Have to agree, if ANY usefull data is on HDD at all, either hammer it or drill it.

Baiting Guru Joined: 08 Jul 2004 Posts: 11857 Location: UK

This tool is apparently good for erasing hard drives or other files, you can configure it to overwrite 1 time, 7 times or 35 times:

http://www.heidi.ie/eraser

Posted: Tue Mar 27, 2007 12:38 am

^^^Although performing a 35 pass overwrite on a 40 GiB drive will take a while........... Wink

Thermite erases everything Cool

Posted: Tue Mar 27, 2007 1:33 am

Split from computer power loss thread.

The hard drive manufactures have utilities to do a low level format of the drive. It writes zeros to the drive. Do that twice if you really are worried but someone would have to spend a couple hundred dollars to a thousand to recover data purposely, securely erased. I think that the CIA recommends 5 times. But they have more secure information than you will ever have. And just like IPs, there is a point where it becomes silly to thermite a hard drive. You run more personal risk destroying the drive that the risk of someone setting out to find your info.

Posted: Tue Mar 27, 2007 1:56 am

What to do?

Ask Shiver: http://forum.419eater.com/forum/viewtopic.php?p=400057

Baiting Guru Joined: 31 Jan 2007 Posts: 12237

The best option has already been mentioned, a hammer.

This is a program that I have used to erase free space on a working HD. (Not that I have anything to hide)

http://www.tolvanen.com/eraser/

It is freeware and clean (void of spyware, et al)

Posted: Tue Mar 27, 2007 2:09 am

If you're severely paranoid, it's only really necessary to destroy the platter(s) which is where info is actually stored. And it's only about 1% of the mass of the drive; much easier to destroy than the whole drive. What I do is open the drive and remove the platter, then reduce it to nothing with a bench grinder. Takes about a minute. Much faster than trying to do a software wipe, and no chemicals involved.

Posted: Tue Mar 27, 2007 2:23 am

@DrWho. Admittedly, I posted the thermite method with tongue firmly planted in cheek.

I'll happily use a mechanical method again on a dead hdd and apply a 7 pass overwrite on a drive that is destined to be recycled. I'm more inclined to keep my older drives and recycle them as portable storage.

EDIT: My local tech college accepts donations of older computer (and other electronic) equipment for training purposes.

Soldering students benefit by being able to practice various repair techniques on real world pcbs and discover the joys of smd work. The IT wannabes are able to learn the basics of computer construction, maintenance and repair at minimal cost to the college.

Master Baiter Joined: 13 Jul 2005 Posts: 186 Location: GA

Metal office trash can.

Lighter fluid.

Match.

Fun for the whole family!

Alternately, the cheapo way that takes time but costs nothing. Delete everything but .dll files on the HD. Copy and paste the .dll's until the hard drive is full.

Then format normally.

Posted: Tue Mar 27, 2007 4:24 am

I like the platters. They're shiny, and they work well enough as mirrors. I have on my desk a platter that I use as a mirror from time to time. Taking it apart FTW!

Still, a simple data-wiper is your best option. Find something that conforms/exceeds to DOJ standards (US) and you should be fine.

If your new computer has the same interface type, you can just hook it up as a second HD, and scramble it a half-dozen times, then format. Presto, done.

Posted: Tue Mar 27, 2007 4:48 am

Quote:

I want to donate it to the thrift store, is it worth it without a hard drive? Is there anything else i can do with it, that won't involve it sitting in a landfill etc etc...

This was the original question. He didn't ask how to destroy a hard drive, he asked if he could safely erase the info off it.

There is no point destroying it. Just erase it by write over it a few times. Deleting partitions and running FDISK will make the data unreadable to a regular program by deleting the FAT but the bits are still on the disk in their correct order. Writing over them will scramble the info to make it harder to recover. That is why low level formating is the easiest.

Yes, I know the thermite was a joke. But it still is not necessary to take the drive apart and drill holes in it or find a grinder or copying and pasting dll files. A commercial wiping program will do that more efficiently. Use a free one.

The type of data extraction you all are worried about after wiping a disk takes specialized equipment and knowledge. Not the kind a person who goes to the thrift store would have sitting around.

Hello I'm New here! Joined: 26 Mar 2007 Posts: 5

DrWho wrote:

The type of data extraction you all are worried about after wiping a disk takes specialized equipment and knowledge. Not the kind a person who goes to the thrift store would have sitting around.

Are you saying that it's possible to recover data even if you have erased a drive and filled it with 1s? I know it's easy to recover from a FAT-error, I even did that myself by finding the safety copy of the FAT stored on the other side of the HDD. But I thought filling the drive with bits would actually erase the information.

Not that I have anything to hide...

Hello I'm New here! Joined: 23 Mar 2007 Posts: 3

Well, thought I'd show another program for erasing hard disks.. Darik's boot and nuke(I didn't see it mentioned above). http://dban.sf.net 100% free.

Slightly unrelated but...

I have a hard drive that failed on me some time ago (my first and only hard disk failure), and the platters are no longer shiny... I'll try some simple green or something before grinding them into dust. Wink

Posted: Tue Mar 27, 2007 8:50 am

The only way to 100% erase a hard drive is total destruction, even if you burn it data can still be retrived. Stick it in an industrial incinerator for 100% risky free erasing

Baiting Guru Joined: 04 Jan 2006 Posts: 3193

It is theoretically possible to recover the contents of a disk after it has been overwritten. If I understand correctly, it has been demonstrated in a lab environment, but no data recovery firms are advertising that they can do it. Who knows what the secret government labs Wink

can do.

The method relies on the head positioning being slightly inaccurate, so the new data is written in a slightly different position to the old data. Recovery of that data can not be done just by plugging the drive into a new computer. At the very least you would need to use your own PCB in place of the one on the drive, if not take the platters out and use your own read-heads.

Overwriting it many times means that you will tend to cover up all the old data. Of course nothing random is certain, so you just have to overwrite it a lot and hope.

I am fairly sure low-level-formatting has not done an actual low-level format for over a decade. The drives are formatted at the factory, have data stored on them, and actually wouldn't work if they were reformatted to that extent. So I wouldn't be certain that it wrote to every block, and it only counts as a single overwrite anyway.

If you need National-Security-type safety then mechanical destruction is the only method. Overwriting it many times gives 99.99% security against any non-magical methods of accessing the deleted data. Overwriting it once will stop anyone without a data recovery laboratory. Formatting it, FDisking it or deleting all the files is totally useless.

If you are going to over-write it, then use an overwriting program; just copying files will leave some data on the disk, even if it's just the names of files, but it may include some of their contents. If, for example, you copy a DLL several times, then that DLL is not going to fill up an exact number of blocks on the disk; the last block is going to be only partially written. Depending on the various factors, there may be old data still in that block.

Any program that doesn't have to write to every byte on the disk, has probably been optimised not to, since we like our computers to run fast.

Since you need to use a specialist program in order to be sure you are writing to every byte on the disk, you may as well overwrite it multiple times.

Baiting Guru Joined: 07 Jan 2007 Posts: 2922

@Dr Who

Thanks for the split-i didn't think i'd get that many answers!!! Very Happy

Thanks to all the rest of you for your answers. Very Happy

Posted: Wed Mar 28, 2007 1:15 am

My understanding is that there is always a ghost image even if you write over the data. The more times you write over it the more ghost images you have and the less easy it is to find the original ghost image you want. Obviously, you have to read the magnetic particles and translate those into 1's and 0's. Here is what the US government recommends.

Quote:

The government standard (DoD 5220.22-M ), considered a medium security level, specifies three iterations to completely overwrite a hard drive six times. Each iteration makes two write-passes over the entire drive; the first pass inscribes ones (1) over the drive surface and the second inscribes zeros (0) onto the surface. After the third iteration, a government designated code of 246 is written across the drive, then it is verified by a final pass that uses a read-verify process.

Posted: Wed Mar 28, 2007 1:34 am

Keep it, put it in your new computer for a couple of extra gigs storage/backup space.

Posted: Wed Mar 28, 2007 4:30 am

DBAN is good if you have the time. (But a really talented computer forensics expert has a chance of recovering data from even a 37-pass overwrite.)

If you need to destroy info quickly (and/or be 100% sure it's gone), you should physically destroy the platters.

I do not recommend thermite, although I have used it before. It is tricky to safely ignite, and will completely melt every piece of metal it comes in contact with. If you don't know what you're doing, you will be in serious danger. Of course if you happen to have a background in chemistry, and you need to destroy a drive, thermite is a fun and effective way... Twisted Evil

I'd just grind the platters to nothing with a bench grinder, or find some other way of destroying them, if you require that the data be completely unrecoverable.

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