HDD Destruction

basmic

superscaper wrote: »

I completely disagree with "There do exist deep forensic techniques, where you can view data previously written", quite frankly no they don't exist. There are no forensics tools that look for overwritten data (except in the minds of hollywood writers), they only look for fragments of leftover data that have yet to be overwritten. In fact only one complete write of turning all the bits to either 1s or 0s will be completely unrecoverable and there are no forensics tools that can determine previous magnetic states.

Basically they look at the magnetic value on the drive, look at the data, and subtract the data value from the magentic value, giving them a residual magenetic value - and so on.

It's not from films, I've seen this documented in a few places a few years ago.

superscaper

basmic wrote: »

Basically they look at the magnetic value on the drive, look at the data, and subtract the data value from the magentic value, giving them a residual magenetic value - and so on.

It's not from films, I've seen this documented in a few places a few years ago.

Actually they look at the deviation from magnetic polarity, (if it's 80 to 95% from being vertical, i.e. 1, then it was previously in a different state, i.e. 0). That was the research I was talking about and using AFM it could only with relatively high certainly predict ONE previous write but no more and it changed depending on properties of the disc and also it assumed no previous writes at all since it statistically became indeterminable. This is physical experimentation in physics labs (which is the "they" I refer to) and has no practical value, unless you're claiming computer forensics labs have somehow bypassed the current state of physics. There has NEVER been a published demonstration of recovering "real" overwritten data from hard drive platters! Magnetic hysteresis of the type you're describing just isn't at all usable to determine anything on modern hard drives. And when solid state drives become the norm it won't even be relevant anyway since there is no magnetic hysteresis.

DickDastardly_2

Thanks all!

SJames_3

I can't help thinking how appropriate superscraper's avatar is.

superscaper

SJames wrote: »

I can't help thinking how appropriate superscraper's avatar is.

You're not the first to say so and I suspect you won't be the last.

S0litaire

Best way is a 2 step process.

1)
get a linux based LiveCD mount the Drive you wish to wipe, then format it then run a "dd" command.

Then:
2)
Remove the drive from the PC open it up and separate the platters, If they are glass disks then just smash them, If they are metal then stick them in a Fire / Oven till the top coat is nice and crispy.

Or

Open the disks and fill with cola and reseal the drive. the Cola will eat into the metal disks and make it harder to recover :D

Saeed

You must have some hardcore stuff on there! Blimey! A couple of complete overwrites and a hammer, followed by burying it in the garden, or someone elses garden if you have some real xxx stuff should do it so that any normal person would not even know where to start recovery

flossy_splodge

So now dear children, let us return to the class..... Seriously. In simple terms please for others like me out there...
EXACTLY what do we need to do for a reasonable wipe of ordinary data not xxx rated!
Just don't want it to be recovered inappropriately but want to pass a couple of old computers on....please, pretty please....:eek:

S0litaire

Well since the "Data Protection Act" came into force it's an offence to handle other peoples data without taking precautions as to it's destruction when it's no longer needed (this goes for paper as well as digital information) so you technically have to go to extremes like this if there is confidential information held on these drives!

anyhoo i's a good excuse to vent some pent up stress on these !!!!!!s! :D

Best one around is "DBAN" (Darik's Boot And Nuke)

Basically you remove all the drive you wish to keep (IMPORTANT!!)
only having the drives you wish to wipe attached to the PC then stick this CD in the drive and reboot! it will ask a few questions then it will erase the drives.

nanokitten

Surely the best way to clear them is to expose them to a high magnitic field.
I guess taking them to the scrappers and getting them picked up by the eelectromagnet if probably an option for anyone without access to an NMR machine.