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What Size Magnet Can ERASE a Credit Card? - YouTube
Channel: Physics Girl
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[Music]
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this is good news
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you don't have the chip
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okay can we keep trying to buy a dollar
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worth of something from you
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yeah yeah
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we're gonna keep trying to erase it with
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like bigger and bigger magnets so we
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want to then try to swipe it but we
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needed to find somebody that only used
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the swipe and not the chip which is like
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nobody except for the farmer's market
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so you're our guy so we're gonna go get
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our magnets and we'll be back my friends
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dan jabril and i went around san diego
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with the goal of testing what size
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magnet will erase the swipey part the
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mag stripe on a credit card by trying to
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pay someone a dollar over and over and
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then touching bigger and bigger magnets
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to the credit card in between tests so
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we'll do we're gonna do the little one
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first i think that's why okay you can't
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even see it it's so small first i'm
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going to go like that yeah does it feel
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like it's pulling at all it sticks to my
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finger more than the car yeah
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interesting okay
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cash
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look at this look at this magnet holy
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jesus that's it
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oh my god just this scratch that's what
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we erased the credit card with
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oh my god that's amazing
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hey i'm diana you're watching physics
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girl just got back from a vacation in
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hawaii visiting my parents can you tell
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but the relevant intro to this video is
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that everything in hawaii is
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like 10 years behind all kinds of things
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like credit card technology every shop
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and vendor says no tip here yet mahalo
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the chip thing got me thinking about mag
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stripes because one they're going away
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well everywhere but hawaii it seems
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which means that soon they're gonna
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become a fascinating relic of the past
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but it also means that there's probably
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a security concern with them so we'll
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get into that two you can hack and mimic
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them which we're gonna talk about with a
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friend of mine who's a hacker and three
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you can erase them i can't believe that
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tiny met like you didn't even like you
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just kind of were like
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the reason i was so shooketh is because
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i keep my credit cards in a case that
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has magnets in it and magnets that are
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much stronger than the tiny little itty
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bitty magnet that erased my credit card
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so why don't these erase my credit cards
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so our next test at the farmer's market
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was to use this giant magnet hold on
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oh no our next test was to use this
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giant magnet at different distances but
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before i show you what happened let's
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find out what we did to the credit card
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with the little magnet and learn a
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little bit about how to hack credit
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cards oh i just drove all live to la to
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meet with my friend sammy kim carr well
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known in the hacker community well
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yeah there was that whole myspace thing
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but sammy made something that's going to
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be really interesting for us to unravel
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this whole
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mag stripe mystery sammy i erased my
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credit cards today you erase them is
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that a good thing or a bad thing
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we should look at the data on it yeah oh
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yeah
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all right so this is black iron oxide
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which is like rust so don't eat it was
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that a question learn i've learned that
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the hard way i wanted to know what was
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actually on a max right and the internet
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said it's magnetic and i thought well
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what if i get smaller really small iron
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particles rather than something big
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and that's what this is all right so
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this is one of my credit cards yeah
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we're doing this this is what you get if
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you actually
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see those tiny the dark and thin lines
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we can convert those straight into the
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credit card number my name is on there
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uh expiration date all of that data is
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in those bits now these are the credit
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cards that you wiped earlier today so i
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don't really see anything on here oh
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yeah no look there's the swirls with the
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lines in between
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do you see that yeah yeah yeah you're
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right there are those tiny lines
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actually here that's actually really
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cool
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so actually those are
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bits of data and he missed a spot
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this whole process inspired us to try
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erasing the credit card while it has
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iron powder on it to see what it looks
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like for a credit card to be erased how
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about this for visualizing some
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invisible physics what we could do now
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is we can grab one of these cards and we
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can actually see what the computer says
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this is a mag stripe reader slash writer
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why do you have these things yeah
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research i can swipe my credit card here
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and then we'll see data here my name is
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my credit card number go wild people but
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we can now use the max proof device and
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grab that yeah what is the mag suit can
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you just what is magic yeah i saw the
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lines i'm like oh that's data and that's
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what i was like i need to want to
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understand how these work can i make one
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like can i make a credit card so i made
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a device where you push a button and
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you're not even touching the reader and
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it sends your credit card number or
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someone else's credit card number
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depending on
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i don't condone that
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no of course not sammy's mag spoof is
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different from like contactless credit
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cards because it's emulating the mag
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stripe technology specifically which is
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important because there's other data
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unencrypted and stored on your mag
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stripe like your credit card number your
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name whether you need to use the chip
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rather than the mag strip whether this
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is a credit card versus a debit card and
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with max poop you can change this info
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so you could use a credit card where
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you're not supposed to like at an atm so
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this is the second version so i'll turn
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this on dongle life
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take max poof this reader is only made
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to be used as a swipe uh authorizing
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processing yeah please sign here
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did you just think approved transaction
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complete i think i keep like 97 of that
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when you're swiping there's just a read
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head in like a reader that's saying oh
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zero one zero zero zero one one it
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really is like north south north south
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north north south south so i was just
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producing that same physical phenomena
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but through an electromagnet rather than
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permanent magnets this was the original
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yeah so that was the original original
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so when the current goes through the
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coil it produces the electromagnetic
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force and then if you reverse the
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current the reverse field is produced
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and then i went to target and i bought
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something with a mag spoof and i was
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like oh my god that's amazing
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sammy has an excellent video on his
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channel that goes into detail about the
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mag spoof and how he made it if you want
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to check that out i'll put a link in the
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description so
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the fact that sami is able to create max
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booth and you could program anybody's
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credit card number on this and change
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the data so that you could use the
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credit card in a way you're not supposed
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to makes me wonder how other credit card
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technologies are different how are they
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more secure so we're going to talk to a
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scientist from the company square about
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that but first we're going to go back to
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the farmer's market with this dance this
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is brilliant so we're just going gonna
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put a stack of these rub the magnet over
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it and then i don't know what keep
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having it or something yeah that seems
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fair we decided to use small sheets of
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paper like a ruler to keep track of how
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close the magnet was to the credit card
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and then we measured the thickness of
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the papers later
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i wonder if my credit card company is
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going to be like 10 times by the same
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vendor
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red
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peppers oh man that's crazy look how
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close that is that's not that big six
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cards there you go
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nothing not even a charger oh man
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it must be
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that's awesome
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after this experiment we measured the
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thickness of the cards and found that
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the difference between six and eight
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cards is the difference between 1.3 and
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1.9 millimeters away from the credit
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card super small difference and then we
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figured out how strong the magnetic
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field was of this magnet at those
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distances thanks to a neat little tool
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on the k j magnetics website where i got
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this magnet and figured out that the
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field was between 5400 and 6000 gauss to
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put that in perspective that's around 10
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000 times stronger than earth's magnetic
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field but other types of mag stripes on
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hotel key cards are much weaker so they
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can be reprogrammed and reused in fact i
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have erased those with my wallet but
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what's important to note here is that
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the thickness of even a piece of leather
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that's say three millimeters thick can
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make the difference of 3 000 gauss so
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you can prevent your credit card from
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being erased by keeping the magnet just
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a little bit further away because the
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magnetic field decays as we say very
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quickly with distance luckily most
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people nowadays are using chips which is
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the last thing that i want to talk about
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why did chips become a thing is it
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because of the security or the
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erasability of mag stripes my name is
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casey wessel i work as a hardware
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engineer at square so for magstripe the
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concern is that someone could insert a
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skimmer into the payment terminal itself
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so skimmers are really easy to make
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they're also very inexpensive and you've
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probably heard stories of people
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inserting them into like gas stations
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and things like that that data is never
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changing so if an attacker is able to
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extract that data they can easily clone
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it onto a new card the chip has a
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microprocessor on the card and it's
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sending different data every time it
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does a transaction the chip is
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constantly changing the information it's
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sending between the chip and the point
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of sale so this makes it really hard for
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an attacker to isolate that information
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so if an attacker were to insert
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something into the terminal itself and
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they did intercept that information it's
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not useful for them to replicate onto a
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new card or to try to do another
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transaction they'd actually have to do
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surgery on the chip itself that can
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require a lot of expertise and also
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costs a lot of money it costs about more
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than a million dollars for that sort of
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equipment we're constantly trying to
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encourage sellers to move over to chip
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payments and contactless payments
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because they are more secure so there
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you have it even tiny little magnets can
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erase credit cards but it all has to do
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with how close the magnet is but there's
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a lot of security concerns with mag
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stripes anyways so yeah subscribe if you
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want more explorations of everyday
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physics things and thank you to sammy
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and dan and casey and jabril and thank
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you for checking out this video and
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happy physicsing
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[Music]
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you
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