How to really delete files ?

[Cojba]

Well, you can see question from the thread title. But I mean it really.

Everyone of us probably heard somewhere(or watched on tv :P ) that deleted files can stiill be recovered. My friend also tryed to convince me, that some guys from PC service recovered his formatted hard disk with some "crazy cool russian program" =)

I'm currently not in need to do that(lol), but I would love to heard some good explain from some pro :D

I already have a conversation with one "pro", and he told me that files can be recovered if formating was "soft". You know what I mean, faster way when you are reinstalling your xp. He also sad that after "hard" format(slower way when installing xp) data cannot be recovered, cuz in that way random 1 and 0 are written on hard disk.

Opinions, expiriencies and knowledge are welcome

 

[Maniac_]

Well, for it to be completely deleted, your HDD has to be "demagnetized".

There are some apps that will destroy your files by deleting them multiple times beyond being recoverable. These apps are often described as "File Shredders".

Like a real life shredder, the pieces can still be put together but it would take a massive effort. In your case, it would take hardware to come into play and "do stuff" with your HDD.
So yeah, if you want to get rid of some hot files, use a file shredder.

 

[wtg]

Darik's Boot And Nuke (DBAN) for destroying data on a whole disk,
Eraser, or multiple free space secure passes in CCleaner to clean "Empty" disk space within a Windows environment,
TrueCrypt for FVE.

Here's a couple of articles:
http://en.wikipedia.org/wiki/Data_remanence
http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html

 

[Cojba]

tnx for your answer Maniac_.

And also one thing just came into my mind. If I completely format hard disk, and after that make it full with some other stuff(example movies) does "bad files" can still be founded or they will be lost forever in order to make space for new files.

 

[FancyPants]

Use Darik's Nuke

Darik's Boot and Nuke ("DBAN") is a self-contained boot disk that securely wipes the hard disks of most computers. DBAN will automatically and completely delete the contents of any hard disk that it can detect, which makes it an appropriate utility for bulk or emergency data destruction.

http://www.dban.org/

Just be warned. I put 48 passes on my old 20gb laptop HDD and it took about 36 hours for it to complete

 

[FancyPants]

tnx for your answer Maniac_.

And also one thing just came into my mind. If I completely format hard disk, and after that make it full with some other stuff(example movies) does "bad files" can still be founded or they will be lost forever in order to make space for new files.

Yes they will be lost but we will need a FULL HD of movies. Enough to cover each sector

Repartitioning just deletes sectors and makes new ones

 

[Maniac_]

tnx for your answer Maniac_.

And also one thing just came into my mind. If I completely format hard disk, and after that make it full with some other stuff(example movies) does "bad files" can still be founded or they will be lost forever in order to make space for new files.

If you "soft format", there will be traces. But the partitions in the HDD will be overwritten with the newer files.
When you format, it is recommended to use the "not quick" way, because the main reason we format our HDD is some virus or a fucked up system, right?

 

[barcodenation]

I had a friend who was in the FBI a few years back and he showed me a trick to get rid of old files. What I did was downloaded a free file off the net (can't remember what it was or where from) but anyway I downloaded the file and copied it multiple times. I just kept copying it until the hdd was completely full. then i formated the drive and repeated the process. By filling formating filling formating it makes all those old files non existant. The files cannot be recovered after the drive has been formatted and filled twice.

 

[CuraHack]

Check out the Ultimate Boot CD (UBCD), this disk has a lot of useful tools, and some to scrable a HDD permanently

 

[l0calh0st]

You can use File Shredders, those tools will convert one file in to thousands of small pieces then it just delete it.

 

[nForc3r]

.... random 1 and 0 are written on hard disk.

This is the key

 

[Tango]

I use evidence eliminator V6, it can multipass/scrub files so the data is totally gone

i read data can still be recovered after 1 pass.

But i dont use it for that, it has a 1 click total system clean to get rid of all the junk windows keeps

 

[Jesse]

You can use File Shredders, those tools will convert one file in to thousands of small pieces then it just delete it.

I use Pointstone shreddar. Comed with the following options:
Single Pass: The fastest, but least secured of the data destruction algorithms. Your data is overwritten with zeroes in a single pass.
Triple Pass: Triple Pass consists of two complimentary overwriting passes followed by a random pass. This is an extra security measure that should prevent any particular recovery program retrieving your data.
U.S. Standard, DoD 5220.22-M (7 passes): U.S. Department of Defense specifies a seven pass extended character rotation overwrite algorithm in the DoD 5220.22-M specification. This Total Privacy shredding method conforms to these overwriting standards as well as method 'd' of the Cleaning and Sanitation Matrix.
U.S. Navy NAVSO P-5239-26 (RLL) (3 passes): This shredding method conforms to the U.S. Navy standard and uses three passes - one flush, one specifically patterned for RLL and one random.
U.S. Navy NAVSO P-5239-26 (MFM) (3 passes): This shredding method conforms to the U.S. Navy standard and uses three passes - one flush, one specifically patterned for MFM and one random.
U.S. Army AR380-19 (3 passes): AR380-19 is the data destruction level specified and published by the U.S. Army. This procedure calls for 3 overwriting passes, one random and a character with its compliment.
German Standard, VSITR (7 passes): The German standard calls for each sector to be overwritten with three alternating patterns of 00 and FF and in the last pass with AA.
Russian Standard, GOST P50739-95 (7 passes): GOST P50739-95 is the purge required by the Russian Federation. This procedure calls for a single pass of zeroes followed by a single pass of random characters.
Peter Gutman (35 passes): Peter Gutman suggests methods for ensuring that the recovery of data can be made as difficult as possible for an attacker by offering the 35 overwrite pass algorithm. This algorithm is slow, but extremely reliable.
Bruce Schneier (7 passes): The Bruce Schneier method offers a seven pass overwriting algorithm. The first with all ones, the second all with zeroes and then five times with a cryptographically secure pseudo-random sequence.

 

[Cojba]

Peter Gutman (35 passes) I think this guy can really delete files

Tnx for your responses, I wasn't thinking that there is the whole science abt this when posted first question

 

[vorazeal]

its like when you delete files from your PC it does not actually get deleted, its still stored inside your HDD.

It only gets deleted if other files overwrites that location of the HDD.

So if i have 100 MB HDD, i delete 50MB movie, O.S will show 50MB free, but that file is still present in your HDD.

Now if you copy another 50MB movie into same drive, new movie overwrites the old file present in HDD and now its impossible to get that file back.