I got the basics. Deleting a file simply tells the system that the sectors it occupied are now available for new data to be written on.
But if you want a more secure deleting why cannot you just overwrite everything with zeroes? If the computer system is only working at its core by manipulating zeroes and ones, why is it said that physically destroying the drive the information is stored on, is the only secure way to make sure nothing is left on it?
In: Technology
There’s a lot of pieces to this this response. None of them are really wrong, but a more modern response is that computers take a lot of short cuts to improve speed and prevent errors. So knowing even basic questions of every possible location some data might be stored is complex.
As a very simple example, when a file is deleted, it doesn’t actually delete the data, it just marks the space as available for use, since actually setting the data to zero takes time and doesn’t add any value. Your computer’s hard drive contains scraps of long-ago deleted files, ready to be be given new values.
Also, the hardware does tricks to improve performance as well. SSD drives try to spread the usage load out across all the parts of the chips (it’ll help them stay good longer). If it sees part being written to really regularly, it’ll secretly swap out where it’s writing to so that area doesn’t become too warn out, without the OS realizing it. Special tools could recover the values stored in that area.
These are just two out of dozens or hundreds of cases where knowing “all places that it’s ever been written to” is hard. That’s when people go dramatic… It’s very difficult to read a melted blob of metal.
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