When you put a file in your "recycle bin" or "trash can" on your computer, it is not really gone - not even after you empty the recycle bin. The information can be recovered with freely available software. Granted, over time the file becomes harder and harder to recover, but it can be recovered.

You can permanently erase a file though. Free programs such as Eraser allow you do erase single files, folders, or even nuke the whole drive. As a matter of fact, wiping the whole drive is the only way to insure that the files can't be recovered.

In the past, people have touted the fact that erasing over a file once was not  secure enough. As a matter of fact, most of these programs will do up to a 35-pass wipe of the file or drive. It looks like you don't need to be that paranoid though. In reality a single pass will do the trick.

even firms specialising in data recovery, openly admit that if a hard disk is overwritten with zeros just once, all of its data is irretrievably lost.

http://www.h-online.com/news/Secure-deletion-a-single-overwrite-will-do-it--/112432

You should also remember that encrypting your whole drive is a much better solution for data protection. You only need to wipe the drive if you think your encryption password has been compromised - or just change the password.

Labels: encryption, erasing data

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From Email:

going to be donating a couple of old computers to Goodwill. What is the best way
to wipe the hard drives? Is reformatting safe enough?
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Simply deleting files in Windows (and most OS'es) doesn't actually delete the data. It is fairly trivial to recover it. The only way to insure security is to "wipe" or "nuke" the data and drive.

Here is a link to Darik's Boot and Nuke (aka DBaN):

http://www.dban.org/download

You can download a floppy image or CD image depending on whether the machines have a floppy drive.

Another option to use is Eraser which runs under Windows. This would be useful if the hard drives are extras or USB type that can be plugged into a Windows computer. Eraser is also useful on any computer - after sending something to the Recycle Bin - you can choose to "erase" the recycle bin rather than just emptying it.

http://www.heidi.ie/node/6

*It has a "create nuke disk" option - but creates a floppy not a CD - for erasing an entire drive.

*With any of these programs, you can typically choose one of several erase methods such as "1 pass" or "35 pass". Typically a 1 or 3 pass is plenty unless there is top-secret data you are worried about. The more passes - the longer it takes.

Labels: erasing data, security