There’s one wrinkle: Magnetic HDDs don’t reliably erase and overwrite completely in a single pass; just like rubbing out pencil writing, it can leave faint impressions under the new content, and it is actually possible (with serious effort by forensic recovery people) to glean some of the previous content.
No, it’s not. At least it has never been done on more than single bits, with an accuracy higher than 50% (which means even when trying to restore a single byte, your chances of it being correct are 1/256).
No, it’s not. At least it has never been done on more than single bits, with an accuracy higher than 50% (which means even when trying to restore a single byte, your chances of it being correct are 1/256).