How Does Fingerprint Scanning Work?
Techquickie
·Techquickie
·2018-05-06
·
829 words · ~4 min read
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so it wasn't that long ago that any mention of fingerprint scanning would
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conjure up images of james bond breaking into a super villain's evil lair these
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days it seems like everyone from secret agents to travel agents is carrying
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around fingerprint scanners built into the smartphones that they're paying 30
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bucks a month for but how exactly do they work and how they found their way
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onto so many consumer devices well as it turns out typical fingerprint readers
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use the same principle of capacitance as track pads and touch screens
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so if you checked out our other episode on touch screens you'll know that they
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typically function by detecting the difference in charge between the lower
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layer of your skin which is conductive and the phone screen itself fingerprint
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readers adapt this concept for personal identification by cramming loss of tiny
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conductive plates into the space just below the scanner surface they're
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narrower than the ridges that make up your fingerprints when you place your fingertip against the reader the sensors
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can tell which portions of your finger their ridges are touching the sensor and
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which are not because the small valleys are further away from the sensor which
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decreases the capacitance the tiny plates will pick up the reader can use
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these differences in capacitance to form a virtual image of the ridges of your
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fingerprint now these scanners have actually been on phones since 2007 but
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only really took off when apple released touch id with the iphone 5s in 2013.
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however there are other types of fingerprint readers too optical scanners
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use visible light to capture a more traditional image of your fingertips but
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these are uncommon at least in portable devices due to their bulk and ultrasonic
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fingerprint readers have the potential to be the next big thing these work
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somewhat similarly to a bat's echo location the way they work out the
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shapes of objects in the dark ultrasonic pulses emanate from the reader and hit
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the ridges of your fingerprints then variations in the return signal are used
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to construct a scan ultrasonic sensors not only have the advantage of a cool
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marketing friendly name but they can also work through other materials
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allowing them to be seamlessly embedded underneath the phone's surface for a
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slicker look or to peer through the crud and moisture on your hands for better
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reliability than their capacitive counterparts sounds great right but while many people
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originally thought the fingerprint sensors as a highly secure technology
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perhaps because of their association with spy films they certainly aren't
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foolproof no matter exactly which variety you're using think of how the
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scanner on your phone will work even though you don't place your finger on it
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in exactly the same position every time this is because they only require a good
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enough partial match to decide that it's your finger now this allows it to
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recognize you from many different angles but it also means there's a small chance
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of a false positive and even though master fingerprints are typically
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secured in some way like how apple encrypts the touch id fingerprint and
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stores it locally it's still possible to defeat fingerprint readers using
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artificial molds that can be created if say some miscreant gets a hold of
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fingerprints that you left on the wine glass so while the technology is super
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convenient there are holes that have led most smartphone operating systems to
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also require a password or pin which is especially important if you're
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one of the few dozen or so people in the world that were born without fingerprints
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quickie in the how did you hear about this section okay guys thanks for
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