Does It Ever Get Deleted?
The Google Ngram Viewer allows you to search words and phrases in 5.2 million books published between 1500 and 2008. It’s a great way to see how the words we use have changed over time,1979 was a significant year.
According to the Ngram Viewer, it was the first year we begin to use the word “delete” more often than the word erase. “Forget” is by far more pervasive in our communication, but how does a computer forget?
When Stalin decided that Trotsky was an enemy of the state, he had Trotsky removed from photos he appeared in with Lenin. Plenty of software tools and professional services allow you to do the same. Don’t just forget the actual attendees of a moment in time, delete them.
But where do things go when they’re deleted?
Moving a file to the trash is just the beginning. To protect against accidental deletion, when thrown in the trash a file remains on your computer in a recycle bin, a directory, where it awaits a more ultimate deletion but can be restored if you wish. When you empty the trash you are warned that you are deleting the files permanently and won't be able to restore them. But when you empty the trash, the physical space inhabited by the file isn’t actually emptied. It’s marked as empty. Available if and when new data needs to be stored somewhere. The file’s home has become available real estate but the file itself hasn’t moved out. Only the pointers have gone away.
Pointers are another type of data on your drive that points to places in memory where the actual file they are referencing can be found. They’re a bit like the table of contents, which means that on most operating systems deleting a file and emptying the trash is like deleting a chapter from a book by turning to the table of contents and marking the chapter as empty. There’s nothing here, do what you want with the pages.
To a computer reading the table of contents it looks like the space is empty but of course, that doesn’t change the fact that the contents of the chapter are still there.
Special data recovery tools look through memory marked empty available to see what’s actually there. If you’re lucky, they can even find a file and save it, bring it back, mark it not available, undeleted. But if some of the files have already been overwritten, there can be problems. The file can be corrupted, melded together with other data like some kind of digital Frankenstein’s monster.
A couple of years ago a laptop that belonged to photographer Melanie Willhide was stolen. It contained many of her recent digital photos. Luckily, the police were able to return the laptop to her. They found it in a car they pulled over, but the thief had wiped the laptop's hard drive clean and had been using it for his own purposes. Data recovery experts were able to find some of her files, still there, on the now-empty space, but the files had been slightly overwritten by things the thief had done. They’d been corrupted. Willhide decided to exhibit the work. She titled the show after the thief who made it possible, “To Adrian Rodriguez, with love.”
If you want to delete the file so completely it can’t even be recovered in a cool, weird way, like Willhide’s photos, you will need to overwrite the unwanted file completely. Deny the file a proper burial and rearrange its corpse with new data. One overwrite should be fine but some people do as many as 35. Even 35 overwrites might not be enough. Sure, the overridden data is hidden, but what about bad sectors? These are parts of a drive that devices can’t access because of failed transistors or physical damage.
An overwrite won’t be able to reach them, meaning any data that was ever put there stays there.
So, if you are the United States Department of Defense and you don’t want to take any risks, you will also shred, physically polarize unwanted drives. The US, Europe, Japan often send such electronics waste to dumps in Ghana. Ghana is known as Earth’s digital dumping ground. Why Ghana? Well, it is cheaper to send unsalvageable electronics to Africa, marked as a donation, than it is to properly recycle them. But there, in these electronic dumps, the files can still be brought back to life. Organized criminals operating in Ghana have managed to successfully recover data from unregulated e-dumps. They’ve been able to find confidential multi-million-dollar agreements, involving the Defense Intelligence Agency, Homeland Security, and the TSA.
If you really want to delete something, destroy it, erase it, time is on your side.