Nothing can completely destroy your files

Many people think that once you bang up your hard drive, all your data is lost, gone forever. Actually, it is possible for it to be recovered.

The way a computer deletes a file is that it tells itself that the space that the file took up can be overwritten. Un-delete software works by just locating the "deleted" file and recovering it (assuming none of the data is overwritten).

File shredders work by "deleting" the file first and overwriting the data. Higher security shredders usually make a few passes over the data to make sure that it's completely covered up. However, it is still possible to recover data using a magnatic sensor or an electron microscope, but that's usually reserved for suspected terrorist computers. Physically destroying your hard drive makes it more difficult to erase data, but not impossible.

There's a special branch of government that specializes like these, called the Computer Forensics Laboratory.

www.dcfl.gov...

It uses a technique called disk splicing to recover data. Basically, they rearrange the fragments of what they have of your hard disk and and use magnetic sensors and electron microscopes to scan for traces of information.

If you don't want your information found, then keep it off your computer.

Oh i beg to differ.




Its pretty obvious that you cant delete everything on your hdd even if you format it or delete the data sectors, theres always that little trace. Those processes use supercomputers to analyse though so the average porn deleter or company e-shredder will be ok.

Best to physically destroy the thing when done.

Yes, this is common knowlege. There are specific standards dealing with deletion of data. The first level ofe deletion considered secure is when the disk is completely written with random data, then erased, 3 times. I learned this at university many years ago.

Also, did you know that there's hidden directories created by windows on your drive which you can't see? (explorer and dos are programmed not to see them) These folders keep a constant, complete log of all your web use. These files can not be found or deleted unless you know exactly what to do.

I do know that Zzub and 3 times is the federal standard of deleting information, its also what windows washer uses.

As for those directories..you can see them after going through a lengthy process listed at...

www....#microsoft.com/

wont burning the thing to hell and back vaperize any data?

Programs like window washer and evidence eliminator claim to delete all these hidden files and such, but I doubt it does that good of a job.

Besides, isn't having some sort of program to delete sensitive data enough evidence itself that your hiding something?

So the question is, how do you shred the shredder?

I sort of agree with Dmsoldier. Burning teh disk can probably screw up most of the data because excessive heat can "kill" a magnet, and hard disks are basically microscopic magnets.

hm, what I learned about the first step a computer does for deleting files is to just rename the file so it can't read it.

Im with you on this one Nerdling. Either that, or a bit of gasoline.

Really good thread guys. Informative at the least.

I just saw this on TheScreenSavers on TechTV. A good way to totally get rig off stuff is to reformat or use Autoclave. Autoclave is a bottable floppy that TOTALLY erases it. Even the FBI and the CIA cant retrieve it. And a great (and fun) to destroy the HDD physically is to take some Thermite and rig some of it right about the HDDs in the computer. then flip some switches. In under a minute the whole PC will be up in huge flames. Thermite burns at 3000F. That will detroy ALL the data.

[Edited on 17-10-2003 by dreamlandmafia]

Actually the technology to retrieve data from magnetic media has been around for quite some time. The file shredders mentioned in other posts will do the job quite nicely for most instances. The extreme techniques are used only to retrieve the most critical data. Anyway many years ago (in the days of magnetic tape), NSA passed a letter around to all parties engaged in sensitive DOD projects. The subject was how to declassify magnetic tapes (even then it was possible to the original data written on a magnetic media even though it had been erased and written over). The qist of the letter was:
To Declassify:
Magnetic Tape with Confidential Information - Writing unclassified information of the classified information.
Magnetic Tape with Secret Information - Deguassing the magnetic tape with proper device - writing unclassified information on the tape.
Magnetic Tape with Top Secret Information - Burn the tape.

you can do whats called a low level format which actually gets rid of the files as far as i understand

Even with a low level format, there is residual information that can be read with the proper techniques. These techniques are used only in extreme circumstances (espionage, terriorism, etc.) but they can be used. The only way to completely remove data from a magnetic media is destruction of the media (burn it). But you only need to do that if you wish to remove extremely critical information.

what if u low level and fill it with a buncha random stuff then low level and repeat taht a couple times, surely it would eventually get rid of the traces

Check this out. Read it and watch the videos that are there. www.techtv.com...

It shows you how to completely do it.

Well this stuff works for 99.9% of the situations. If you want to remove financial information, kiddie porn, etc, these things will do the job. The extreme techniques are used only for extreme situations and unless you are deeply involved in a situation such as espionage against the United States, the file shredders will remove the data quite nicely. The techniques I discussed (developed by NSA many years ago) are used only for the most extreme situations. Now if you happen to have some CIA crypto codes on your PC you might have reason to be paranoid. But if you want to remove pornographic love letters to your girl friend the standard file shredders will do.

Well... the government knows my secrets now...

I could always "accidentally" drop something heavy on my computer.

Computer's are too expensive...

Physicaly taking the pieces apart and destroying them is the only way to 100% guarantee that the data is non recoverable. Those in the know can dismantle the drive and read the imprints made to the drive film.
Formating on any level does not totally work.

Any sort of formatting or "deleting" is just overwriting the data. There's no such thing as actually "destroying" the data. It's all overwritten. The way they recover the lost info is that they look under the overwritten layers. Once again, overwriting makes it alot more difficult, but not impossible.

Yep, I agree. By destroying, I meant physically destroying it.

Physically destroying it is your best bet for getting rid of the data. However, it's important to make sure that ALL fragements are destroyed. Even the smallest piece can prove useful (considering the ever increasing density of todays hard drives).

I remember that evidence eliminator had a function that if you selected it, it would erase the data so throughly, that even electron microscopes can't get to it. Does anyone have any info on that? I doubt that it really works.

Also shredders sometimes keep a log of the work that they done, so that also poses a security risk.

There's a part of your computer called the keyboard buffer, which basically stores what you type into a temporary memory (or at least I think it's temporary). It's like when your posting, everything that goes into that little box is in the keyboard buffer. Since it's one of those hidden files hidden in one of you comp's hidden folders, there's really no way to get to it, and I think that most shedders can't get to it either.