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all right let's be honest at some point you've had data stored somewhere that

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you wanted to get rid of without a trace whether it's embarrassing browser

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history photos of an ex or that really

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questionable piece of fanfic you wrote one lonely night

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i still think it's good of course there are methods that are fairly foolproof

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such as subjecting your drive to a fireplace chainsaw or sledgehammer but

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let's say you don't want to go to such extremes and you just want to wipe your

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drive without there being any realistic chance of that data being recovered

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later how would you go about doing this the answer depends on whether you have a

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traditional mechanical hard drive or one of those newfangled ssds we'll start out

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talking about hard drives and why simply hitting delete or emptying the recycle

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bin doesn't securely erase your data

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as we discussed in this episode deleting a file in Windows forces the operating

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system to see the part of the drive it took up as free space that's available

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for something else now but the contents of the file are still there and can be

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easily recovered so the conventional wisdom to solve this dilemma is to

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overwrite the file with random ones and zeros

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this can easily be done on a per file basis or by wiping the entire drive with

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a number of freely available software tools but if you look closer these

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programs often give you lots of options for overriding your drive many times you

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can choose between 1 3 7 or even 35

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passes of zeros ones or a random mix of data that may or may not follow a

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certain pattern at all but if you're erasing lots of data this could take a

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very long time on a slow mechanical hard drive so is it really necessary to scrub

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your platters over and over again well the answer is

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probably not you see the notion that you have to override a drive tons of times

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comes partially from the idea that read write heads on older drives wouldn't

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perfectly flip bits from one to zero when they needed to be changed

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so a bit read as a one by the computer might be something more like

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1.03 so in theory you could use these

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imperfectly flipped bits combined with the magnetic signature left by the read

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write head on the platter to determine what data used to be on it

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hmm that sounds complicated well turns

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out that it is and we don't know that anyone's ever actually recovered data

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from a disk this way in fact the author of a famous paper that promoted the 35

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pass method later noted that overriding that many times on a modern hard drive

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was complete overkill and even used the word voodoo to describe people's belief

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that his own method was the only way to securely wipe data so the bottom line is

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that one good complete passive your drive with an overriding program or

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maybe two if you're feeling paranoid should be enough to thwart any snoops

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but what if you have an SSD well ssds work quite differently in that

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when you delete a file a feature called trim built into most modern drives will

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wipe the unwanted data in an effort to prevent it from being copied

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unnecessarily and if you're curious about why that would happen we discuss

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it in this episode but the point is that a modern SSD should delete a file for

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good on its own although you can always run the trim command manually like this

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if you're using Windows so if you're following these simple steps there

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really isn't much a snoop or even some spy agency can do to see what was once

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on your drive but of course do keep in mind that you have to know where the

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data is if you want to spot delete it many programs like web browsers write

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sensitive data to places on your drive you may not expect so if i were you i'd

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just wipe the entire drive and do a fresh os install before selling or

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giving away your pc you never know whose hands it might end up in even i did i

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wouldn't get caught do you have an extra five minutes per day then use brilliance

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