If I write all zeroes or ones to a hard disk, does that effectively and securely wipe it?

Question

If I wanted to completely and securely wipe a hard drive, could I simply write all ones or zeroes (or even just random zeroes and ones) over the entire disk to clean it? It'd probably take forever, but is my theory correct?

Answer 1

That should suffice. There is a theory that you need to do this multiple times because of variations in tracking, however the threat countered by this seems largely theoretical.

You may find it easier to use a drill or a very large hammer.

Answer 2

Once upon a time there was a man named Peter Gutmann who suggested that with the use of an electron microscope you might be able to figure out what was once written to a part of a hard drive that had been overwritten. That lead people to come up with policies like “you have to overwrite 7 times before it is safe to dispose of.” However, despite all the assurances I’ve heard that it can be done, nobody knows anyone that has actually done it. A couple years back I took a forensic class with Mike Murr from the SANS institute and he was talking about this very thing.Everyone knows someone that has done it, but nobody has done it themself.

As a general guide line, wiping the drive 3 times is the maximum wipe count that I will use. Beyond that is overkill, unless your are dealing with extremely sensitive data.

Any data recovered after 2 wipes, is probably impossible. 3 or 5, would make it virtually impossible.