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InvisibleDazedSol
old hand

Registered: 08/01/01
Posts: 1,230
text doc.s and .....deleting stuff for good
    #1131939 - 12/11/02 10:08 AM (14 years, 2 months ago)

Ok lets say someone has a bunch of text documents(well actually microsoft word/works text doc) and they are PGP encoded on a disc.... Now say this person views his/her documents on the computer....... after viewing this person closes everything down, takes the disk out and shuts down the computer.......is there anyway someone can view anyparts of these files after the disk is out of the picture? I mean does the computer(window OS) store/backup anything like that?
On another note:
Also how can someone ensure that documents that have been deleted are really totally gone from the computer? I see ads for programs that supposively delete and ensure once they are deleted they are gone(no chance of being recovered)..... Is that something that can be without a seperate program? Are there decent free/shareware progs for this?


ok thanks guys....any info greatly appreciated  :smile: 


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Peace,
Adam


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Offlineartemus
nerd
Registered: 11/19/02
Posts: 7
Loc: Finland.
Last seen: 12 years, 5 months
Re: text doc.s and .....deleting stuff for good [Re: DazedSol]
    #1132231 - 12/11/02 12:00 PM (14 years, 2 months ago)

A program on a modern PC (386 and newer) sees the whole memory "spectrum" and tells the operating system that it wants to use this and that part of it. The way this works under the hood is that each programs memory space is divided in blocks and the operating system keeps tracks on which are in use in which aren't. And of course, only the one's in use are actually stored in memory. The thing is that the memory range is 4 GB, which is a lot more memory than most PCs have. To make sure that it won't run out of memory, the operating systems uses the hard drive as a secondary memory for blocks that haven't been used in while.

If you, ehrm, "this person" were viewing the documents it means that the document was somehow stored unencrypted in the memory. And if you were running other programs at the time or the documents were too big to fit in the memory all at once (or for some other reason), it is very likely that at least parts of the documents were at some point written to the hard drive. Of course, the data will be overwritten as soon as there's a need for it, but if you turn off your computer directly after viewing the documents, there's a big chance a lot of it is still on the hard drive.

I don't know how paranoid you have to be about it though, because I have no clue of how smart cops are (that's what we're talking about here, right?). But it's dead simple to read this swapped data if you know how to, and the only way to be completely sure that it's gone is to overwrite it with some random crap before you turn your computer off. There are probably programs that do this, but I don't know the name of any (for Windows at least, in Linux you can probably just run mkswap -c or something after running swapoff in the shutdown scripts).

Oh, and since reading and writing to the hard drive involves mechanics that are terribly slow and you therefore want to read and write as little as possible, regular files aren't really deleted when they are "deleted". The blocks they occupy on the hard drive are just marked as "unused", but the actual data is still there until it's overwritten with something else. There are programs that will overwrite these blocks, and there's a hell of a lot of them for Windows, if I'm not mistaken. You shouldn't have any trouble finding one at www.tucows.com or www.download.com.

Another thing to note is that it is theoretically possible to recover the data if it was overwritten with a known pattern (such as all ones or all zeros), so make sure the program writes random data! (Of course, this is shit you don't have to worry about unless you have Bin Laden's whereabouts in those documents and CIA finds out about it).


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InvisibleDazedSol
old hand

Registered: 08/01/01
Posts: 1,230
Re: text doc.s and .....deleting stuff for good [Re: artemus]
    #1132477 - 12/11/02 01:31 PM (14 years, 2 months ago)

Wow thanks :grin: very informative........its not so much that im...hehe...errr...this person is hiding anything.....just more or less curious if for some reason or another stuff did have to be hidden(who knows...maybe information will be illegal some day :tongue:) that there are ways to do so and be able to view them at a later time 


--------------------
Peace,
Adam


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Invisibledaussaulit
Forgetful

Registered: 08/06/02
Posts: 2,894
Loc: Earth
Re: text doc.s and .....deleting stuff for good [Re: DazedSol]
    #1132498 - 12/11/02 01:41 PM (14 years, 2 months ago)

I got this program called SecureClean. It's pretty good. You can right click on the file and "zap" it. You can set it from 1 to 35 overwrites before it deletes the file so it's impossible to recover. Just in case you already deleted files before you got the program you can also SecureClean your drive. It'll write over your hard drive's free space with trash and then delete the trash to make sure any last traces of data are gone.

If your going sell your computer after you format your hard drive, contents can still be recovered with a data retrieval program. There are other programs you can find at download.com that'll really clean your drive.


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OfflineJssMthrFcknChrst
Son of the LordGod Almighty

Registered: 10/12/02
Posts: 446
Loc: Vatican City
Last seen: 12 years, 5 months
Re: text doc.s and .....deleting stuff for good [Re: DazedSol]
    #1136113 - 12/12/02 05:44 PM (14 years, 2 months ago)

A couple things here:

The only way that you can really consider the data gone is if it is written over at least 8 times with random bits. The more the better! Professional data recovery specialists (read: government agencies) have the skills to find what bits were what through several layers of overwriting.

A word about Microsoft Office programs. When you open a document, a copy is made for backup in case the program crashes while you are working on it. If you were reading a Word document a backup file was created and deleted. Because you can't tell where that file was created, you would want to clean all you free space.

Another thing about Word, though a little off topic, is the GUID. Every Office document includes a Globaly Unique IDentifer, which is a number created through a formula including specifics of the computer hardware and office installation information. This GUID, along with the Computer Name, Owner Name, and other personal information stored on the creating computer and any computer that the document was edited on are all stored in the document and can be used to track the origins of the file. People have been caught for creating Macro-virii through these methods. I'm not positive on this, but I believe any email created in Outlook would include all this information as well.

Watch you ass
Jesus Motherfuckin Christ


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Invisibledaussaulit
Forgetful

Registered: 08/06/02
Posts: 2,894
Loc: Earth
Re: text doc.s and .....deleting stuff for good [Re: JssMthrFcknChrst]
    #1136782 - 12/12/02 09:53 PM (14 years, 2 months ago)

Hmm, well that does make me wonder if that program actually works. Anyone know of a good data recovery program that's fast?


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OfflineJssMthrFcknChrst
Son of the LordGod Almighty

Registered: 10/12/02
Posts: 446
Loc: Vatican City
Last seen: 12 years, 5 months
Re: text doc.s and .....deleting stuff for good [Re: daussaulit]
    #1137307 - 12/13/02 04:37 AM (14 years, 2 months ago)

Remember that US spy plane that China captured? Well, the crew was in the process of destroying the data on the plane when they were captured. The US Military approved method of doing so: Hammers, incerators, and other lowtech solutions.
If you have ever done anything illegal on your computer, i would not recomend selling it with the harddrive intact. Buy a new hard drive and trash the old one. Take a drill and put tons of holes all through the drive, then take it apart and smash each and every part with a hammer. If you're really paranoid, make some thermite and reduce it to a melted pile of metal.

Jesus Motherfuckin Christ


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OfflineSeussA
Error: divide byzero

Folding@home Statistics
Registered: 04/27/01
Posts: 23,480
Loc: Caribbean
Last seen: 1 month, 19 days
Re: text doc.s and .....deleting stuff for good [Re: JssMthrFcknChrst]
    #1142912 - 12/15/02 12:18 PM (14 years, 2 months ago)

When I worked for the feds, in a secure area, we were not allowed to remove any hard drives (or anything else for that matter). When we upgraded all the computers, they brought in a machine similiar to a paper shredder that turned the hard drives into a pile of metal chips.


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Just another spore in the wind.


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