I’ve recently purchased a new computer, and I will probably end up giving away my old computer. I’ll be deleting most everything except Windows and Microsoft Office from my old computer’s hard drive. For security and privacy reasons, I’d like to make sure that the stuff I delete will be gone permanently, and can’t be recovered. Is there a good method for doing this, or a good shareware/freeware program that does this? I don’t want to hear suggestions like “format the hard drive,” because I don’t want to erase everything, and I’m not willing to re-install Windows and other such programs afterwards. I have Norton Systemworks, if that helps.
Defragging the drive should do it. Unless somone like the FBI REALLY wants the data.
There are several available “erase” programs which physically overwrite specific files or specific parts of the filessytem like the free list multiple times with patterned or random data.
Defragging won’t neccesarily do it, if you’re being intensively paranoid.
Poke around your favorite shareware site, or one such utility may be found here:
download a program called Mutilate File Wiper. It has options to write random (or user-defined) patterns, to either a single file or all free space on the drive, a specified number of times. the default is all ones, followed by all zeroes, followed by alternating ones and zeroes, once each. 7 total overwrites is the government standard for secure deletions on non-top-secret systems. Anything with higher classification gets incinerated, which is the only truly perfect file deletion method.
But this one is good.
And no, defragging the drive won’t do it.
isn’t it possible (though maybe time consuming) to just fill of the HD after deleting the old files? There are programs that will do this (any type of media recorder for example). Or can old files still be recovered, even if they’ve been overwritten?
Does a “restore” delete everything?
I downloaded Eraser from the first link and I’ll give it a try when I’m ready. My new computer is supposed to arrive tomorrow 
If you are command-line savy, check out sdelete:
http://www.sysinternals.com/ntw2k/source/sdelete.shtml
You can tell it to delete files, recurse directories, and even to scrub the empty space on your hard-drive (to catch files that have already been deleted normally).
And best of all it is free.
As an aside, http://www.sysinternals.com is a great site if you do any Windows system programming. It is full of great tools and all of them are free; many with source code.
Well, no. “Steal This Computer Book” (Wang) gives pretty accurate advise that disk clean/erase programs are not complete enough.
My suspicion is that if you really want your old files destroyed the only way is to smash/burn/de-magnetize (repeat the above a couple of times) your harddrives to have a real chance at securing old files.
I would get a hex editor and wipe the files out from the inside, that way if someone ever were to recover them they would be useless.
What does defragging have to do with deleting? You don’t lose information during defragmentation, you just rearrange it. Or is there something I don’t know?
If you rearrange everything on your hard drive, odds are that the space on the drive that held the ‘deleted’ files will have been copied over. It’s about the best way to get rid of files that doesn’t require some utility that doesn’t come on your computer, though not perfect.
Of course, that depends on how fragmented the drive is in the first place. In the absence of a wipe utility, you’re probably better off simply deleting the files, then filling up the disk with something, even by just making copies of existing files.
The reason the DoD requires you to write over each bit 7 times is that with the proper equipment, you can tell what was on a disk even after it has been written over once. If a bit has been set for a period of time, there is enough “memory” (bad word for it, but you get the idea) that can be read.
If you going to give away the computer why dont you just go to Run and type format C:
I would think that would make it very hard for anyone to access the files if not imposible
felix9x: Formatting may make it difficult for a casual user to get the data back, but with enough work even software can do it, to say nothing of a data recovery service.
In reality, there is no way to wipe data from a magnetic storage medium without completely destroying it. I recall a paper that I believe was linked from slashdot that said that a magnetic field strong enough to completely erase all data would incidentally also warp the platters very badly.
As I recall, one of the major problems was that it was nearly impossible to wipe the harddrive’s onboard error correction database because it is fault tolerant so some insanely huge degree.
Naturally, this all depends on the level of security you desire. You’ll need to burn any drive you absolutely want no data pulled off of:)