all right let's be honest at some point you've had data stored somewhere that
you wanted to get rid of without a trace whether it's embarrassing browser
history photos of an ex or that really
questionable piece of fanfic you wrote one lonely night
i still think it's good of course there are methods that are fairly foolproof
such as subjecting your drive to a fireplace chainsaw or sledgehammer but
let's say you don't want to go to such extremes and you just want to wipe your
drive without there being any realistic chance of that data being recovered
later how would you go about doing this the answer depends on whether you have a
traditional mechanical hard drive or one of those newfangled ssds we'll start out
talking about hard drives and why simply hitting delete or emptying the recycle
bin doesn't securely erase your data
as we discussed in this episode deleting a file in Windows forces the operating
system to see the part of the drive it took up as free space that's available
for something else now but the contents of the file are still there and can be
easily recovered so the conventional wisdom to solve this dilemma is to
overwrite the file with random ones and zeros
this can easily be done on a per file basis or by wiping the entire drive with
a number of freely available software tools but if you look closer these
programs often give you lots of options for overriding your drive many times you
can choose between 1 3 7 or even 35
passes of zeros ones or a random mix of data that may or may not follow a
certain pattern at all but if you're erasing lots of data this could take a
very long time on a slow mechanical hard drive so is it really necessary to scrub
your platters over and over again well the answer is
probably not you see the notion that you have to override a drive tons of times
comes partially from the idea that read write heads on older drives wouldn't
perfectly flip bits from one to zero when they needed to be changed
so a bit read as a one by the computer might be something more like
1.03 so in theory you could use these
imperfectly flipped bits combined with the magnetic signature left by the read
write head on the platter to determine what data used to be on it
hmm that sounds complicated well turns
out that it is and we don't know that anyone's ever actually recovered data
from a disk this way in fact the author of a famous paper that promoted the 35
pass method later noted that overriding that many times on a modern hard drive
was complete overkill and even used the word voodoo to describe people's belief
that his own method was the only way to securely wipe data so the bottom line is
that one good complete passive your drive with an overriding program or
maybe two if you're feeling paranoid should be enough to thwart any snoops
but what if you have an SSD well ssds work quite differently in that
when you delete a file a feature called trim built into most modern drives will
wipe the unwanted data in an effort to prevent it from being copied
unnecessarily and if you're curious about why that would happen we discuss
it in this episode but the point is that a modern SSD should delete a file for
good on its own although you can always run the trim command manually like this
if you're using Windows so if you're following these simple steps there
really isn't much a snoop or even some spy agency can do to see what was once
on your drive but of course do keep in mind that you have to know where the
data is if you want to spot delete it many programs like web browsers write
sensitive data to places on your drive you may not expect so if i were you i'd
just wipe the entire drive and do a fresh os install before selling or
giving away your pc you never know whose hands it might end up in even i did i
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