April 2, 2014 • 33 mins
How has the Digital Age improved the centuries-old practice of fingerprinting? We explore the history of fingerprint tech and explain how modern scanners use optics, capacitance, heat and ultrasound to create prints that are harder than ever to hack.
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Speaker 1 (00:04):
Get in touch with technology with text Stuff from how
Stuff Work dot com. Either everyone, and welcome to Text Stuff.
I'm Jonathan Strickland and I'm La. And you know, we
had to actually verify our identities before walking into the podcast,
which is just standard operating procedure here in How Stuff Works.
(00:25):
Oh right, it's a it's a blood sample, retina scan,
and fingerprint before we're allowed to enter any doors. Yeah,
it's really awkward. That's why most of us no longer
wait till the last minute to have to run to
the bathroom because disaster can strike. But it does mean
that we thought, hey, we should talk about biometrics, and
then we started looking into it and getting really excited,
and then we realized, hey, there's a lot to talk about, right. Biometrics,
(00:51):
of course, being the measurable biological or behavioral characteristics used
for for any given individual. Yes, this is what how
the FBI says, this is what the biometrics are. So, uh,
you know, it's one of those things where we knew
it was a huge topic and we decided to narrow
it down. So today we're specifically focusing on your fingerprints,
(01:14):
well not your fingerprints, I mean, I mean everyone's fingerprints. No,
see the person sitting next to you, No, not that one,
the other one, that person's fingerprints. That's that's the one
we're concentrating on. So yeah, because everyone has has different fingerprints,
I mean like everyone, right, And this is something that
has been known for a while but then forgotten and
then rediscovered. So we're going to talk about that because
(01:35):
it's kind of funny. So these days we think of
biometrics as sort of those automated ways to verify your
identity based on some sort of biological characteristic, like you know,
the eye scan or the fingerprints scan or whatever. Vocal
scans as well, you know, like the voice imprint. Lots
of different Hollywood versions of this. But you know, again,
(01:56):
going into that fingerprint approach, we thought that, you know,
we we look at not just how we've defined it
and how stuff works, but look at a whole history
of fingerprinting. U We're not the first podcast to do this,
by the way, certainly not. Josh and Check of Stuff
you Should Know did an episode on April called how
(02:16):
Fingerprinting Works, and they go pretty deeply into the history
and say many pithy things. So if you would like
to check that episode out. You can go to Stuff
you Should Know dot com right and just stick around
because we're gonna say some pithy things too. We are
going to cover some of the history, kind of a
quick overview. But first I thought I would read a
couple of little excerpts from our article on how fingerprint
(02:38):
scanners work, because there are a couple that I thought
were really interesting from how stuff Works dot Com. Neither
of us actually wrote this. Nope, Nope, I didn't write
this one. This one says people have tiny ridges of
skin on their fingers because this particular adaptation was extremely
advantageous to the ancestors of the human species. The pattern
of ridges and valleys on fingers make it easier for
(02:59):
the ends to grip things in the same way a
rubber tread pattern helps to attire grip the road. The
other function of fingerprints is a total coincidence. Like everything
in the human body, these ridges form through a combination
of genetic and environmental factors. The genetic code and DNA
gives general orders in the way skin should form in
the developing fetus, but the specific way it forms is
(03:21):
a result of random events. The exact position of the
fetus in the womb at a particular moment, and the
exact composition and density of surrounding amniotic fluid decides how
every individual ridge will form. This, by the way, is
how identical twins can have different fingerprints. Pretty cool because
you know, genetically they're identical, but their fingerprints are different,
(03:42):
still different. Interesting. So looking at this history, you might think, Okay,
I've heard about fingerprinting, particularly when it applies to law enforcement.
That's probably where a lot of people are familiar with it.
Besides the verification. Sure, sure, and uh and a couple
popular media pieces have talked recently about Um. I mean
(04:02):
you you get things like Ripper Street or Sleepy Hollow
having characters going like this new fingerprinting thing in the amazing,
amazing age of Victoria. Um, not not so much. Actually,
so fingerprints people, Well, first of all, people have been
aware of them for ages because we're curious folks, you know,
human beings. We we were very curious and narcissistic. We
(04:24):
like to learn stuff, and we like to look at ourselves.
And how do I know that this dates back? Are
ages and ages and ages ago because we have prehistoric
depictions found in Nova Scotia uh, and it depicted a
hand with ridge patterns on the skin. Now, that does
not mean that the ancient Nova Scotians were familiar with
(04:46):
the fact that all the fingerprints were unique and therefore
no two individuals had the same ones, but at least
show that, you know, yeah, they noticed them. Yeah, but
the ancient Babylonians may have actually used ping of prints
to differentiate people. Um, we've found fingerprints in clay to
to sign business transactions, and the ancient Chinese used inked
(05:08):
fingerprints for both business purposes and child identification. And in
the thirteen hundreds in Persia, official government documents often included fingerprints,
probably to indicate they were authorized and official. Now, according
to the US Marshall's Office, which has an entire web
page devoted to fingerprinting in the history of it, one
(05:28):
government official in Persia at that time made the observation
that no two fingerprints were alike, which obviously would be
very important if you're making a document official or authorized.
But it wasn't until the eighteen eighties that that amazing
Age of Victoria previously mentioned that we got some kind
of official classification system, right. It wasn't until the modern
(05:50):
era that we started seeing it in UH story. It
wasn't even in wide use at the beginning. It was
just kind of exploratory. Dr. Henry Faulds back in eighteen
eighty posed using fingerprints for identification as well as a
means of classifying them. So he forwarded these ideas to
a certain Charles Darwin, very important historical figure in his
(06:12):
own right. But Darwin at the time was towards the
end of his life and felt that he did not
have the necessary UH time and energy to devote to
this thought. It was really interesting, however, so he forwarded
the information along to a cousin of his named Francis Galton.
So false would write a scientific paper about his methods
and actually identified a fingerprint. Ascertain the identity of the
(06:36):
person who left that fingerprint on bottle of alcohol shouldn't
come as any surprise. I guess who brings it all together?
It does. Then in three Mark Twain would would use
this this new startling scientific information in a story. Yeah,
it was in Life on the Mississippi, and in that
(06:58):
one of the elements of that stories of order is
identified through the use of fingerprints. And he would revisit
the idea in a book called Putting Head Wilson. Putting
Head Wilson. Yea, so it's interesting. Now this was before
anyone was actually using uh, fingerprints in any kind of
criminal investigations on an official basis. It had not been
(07:19):
science fiction, really was it kind of was so so
that was exciting. But but soon in eighteen eighty eight,
Sir Francis Galton, remember the cousin to Charles Darwin, who
had received information about this about ten years previous, um
began his own study of fingerprints. Yep. He wrote a
book in eighteen ninety two and put forth a formal
classification system and identify the tiny characteristics used to differentiate fingerprints,
(07:44):
which now we call Galton's details. He also observed that
fingerprints don't change over the lifetime of a person, so
the ones you have when you're a kid are the
same ones you have when you're old. Originally wanted to
kind of link fingerprints to certain types of traits like
intelligence or heredity, which is so racist. Yeah, kind of essentially,
(08:06):
I think this was almost in an attempt. And I
don't know enough about Galton to say this for sure,
but it seems like an attempt to justify certain society's
beliefs in certain people, that kind of thing. Yeah, it
wasn't necessarily so racist, but um, but it's kind of
it kind of runs in that direction. Yeah, because I mean,
the idea that you could identify a person's intelligence based
(08:28):
on their fingerprints already seems a little sketchy, And in fact,
he did determined that there was no connection. There was
no there were no identifier marks in a person's fingerprints
that would give you any clue as to that person's
intelligence or genetic background. However, he did figure out that
there were a lot of differences and that people didn't
(08:48):
weren't likely to have the same fingerprints. Yeah, unlikely, in
the order of one in sixty four billion, that's pretty unlikely.
So in eight we get the first use of fingerprints
in a criminal investigation on an official level. Uh one vs.
Tech And I'm sure I butchered his last name. Who
(09:10):
was a police officer in Argentina used them in a
murder investigation. It was actually a really tragic case, but
the discovery meant that he was able to solve this
mystery and prove that the person that was believed to
have been the murderer was in fact not the killer.
So Uh, not only was it the first use, but
(09:32):
it was a pretty dramatic example of it. Now, between
we're gonna skip to nineteen eighteen, but between the late
nineteenth century and the early twentieth century he started to
see fingerprints get adopted into various legal organizations all around
the world. The United Kingdom and the United States were
leading the way, but it was all over the place.
(09:53):
So by nineteen eighteen you have Edmund Lekard who says
that you only need twelve points of similarity between an
individual's fingerprint and a target fingerprint to serve as a
positive identification. Now you may have heard about those twelve
points of singularity, that this is somehow like a legal thing,
that if you were able to meet those twelve points
(10:14):
of singularity, you have the legal basis to say this
person did this. Uh, not necessarily a legal definition at all.
In fact, UH, countries have very very different ways of
saying whether or not a fingerprint is a valid match
for another one, and some, like the United States, do
(10:34):
not have a minimum number of resemblances that need to
be there in order for you to call it a match. Now,
usually law enforcement agencies rely on experts who give their
expert opinion and therefore putting their own reputation on the
line as to whether or not something matches. And of
course now these days we rely very heavily on digital information,
(10:56):
which with very very complex and intelligent i'll rhythms, that
will that will do some really interesting like work. Yeah,
and so with that, you know, the the level of
a confidence grows quite a bit. So, uh, just so
you know that twelve points of similarity not necessarily a
legal standard. Nineteen four, that's when Congress enabled had an
(11:18):
act that established the new division for the Federal Bureau
of Investigation also known as the f b I. UH
and this division was called the Identification Division. I bet
you can guess what it did. So it became kind
of a centralized fingerprint file for the entire country. So
not it wasn't necessarily uh standard procedure for every law
(11:39):
enforcement agency out there to send a copy to the FBI.
But that's kind of what started to happen, so that, uh,
there could be this sort of cooperation between different departments
which often wouldn't have any communication with each other. Sure sure,
by ninety six, the FBI would have processed more than
a hundred million fingerprint cards. Yeah, not just processed, but
(12:02):
they did that by hand, right, right, and it would
be two million by two million physical cards with fingerprints
on them. I mean, just imagine how many, Like how
how much storage you need just for me? It's two
I can't even I can't even imagine it. But by
the FBI introduced the Integrated Automated Fingerprint Identification System or
(12:27):
if SO. It's the largest fingerprint database in the world,
and its computer automated. It takes about twenty seven minutes
for the system to comb through every single file in
its database to find out if there is a potential match.
During a criminal investigation, it's different. If it's a civil case,
it's actually like more than an hour. But for criminal investigation,
(12:50):
for all the criminal files that are storing this database,
twenty seven minutes from the time you actually input the
suspects fingerprint. I imagine that's a lot faster than whatever
in her and they sent down to the basement, Well yeah,
because I mean you would have to narrow down the
person quite a bit before you could ever start coming right,
(13:10):
this is a man, So cut out all the women
and then go like there are seventy million of them
down there. Uh yeah, that would be that would be
a daunting task. So in the digital age, we can
actually analyze this stuff way better than we ever could,
Like you don't have to use the naked eye anymore
and try and find those little ridges and stuff. You
(13:30):
can actually rely very heavily upon computer systems. And once
we started getting those computer systems in place, they pretty
soon thereafter became um commercially available. Yeah. Yeah, we had
some fingerprint verification systems that have been around for a
few decades now. On the consumer level, they've only been
available fairly recently. And you might be thinking, oh, yeah, yeah,
(13:53):
the iPhone five s because it has that that fingerprint
scanner where you can use that to log into your phone.
That's the first smart ohne to ever use that, right, Nope, no, no,
there's actually a mobile device. The first mobile device that
I found was a one that dated from two thousand three,
the H and Boy. The name of this is phenomenal.
HP names their products in such catchy ways. It's the
(14:15):
HP I pack, I p a Q P PC pocket PC.
Oh yeah, it just rolls off the tongue. Yeah, it
really is. I mean, with a name like that, how
could you resist I phone my phone. So at any rate,
this was the first mobile device to incorporate finger scanning technology.
(14:37):
But it was also sort of the edge of a
boom for the technology. UM it was being extended for
for wide consumer use at the time. I mean, you know,
keyboards and mice had UM, laptops had him. You can
buy a USB scanner for multipurpose use and encrypt everything
with your fingerprint, right, you could end up creating, for example,
with a copier, you could end up telling people, all right,
(14:57):
this group of folks are authorized to make copy. Anyone
who's not on this list cannot make copies. And you
would walk up to make copies. And if you weren't
on that list, then I guess no fun Christmas party
Shenanigans for you. But but but but also opening this up
to the consumer market meant that a lot of people
started finding the flaws in the technology. Oh yes. In
(15:18):
December five, clarks And University researchers announced that they could
fool of the world's fingerprint scanners using an incredibly sophisticated,
expensive substance. Yeah, they could just go out to toy
store and buy some Plato and essentially make a copy
(15:38):
of a fingerprint and put it on any optical scanner,
and we'll talk about the optical scanners in a little bit.
And it worked really well. So that gave people some
pause and thought, maybe we should come up with something
besides optical scanners too, because fingerprint identification is a great idea.
But if it's if it's that easy to fool, we
have to find a different way of measuring it. So
(16:00):
then there was a totally different expose on September twenty one,
two thousand and six, when our beloved MythBusters decided to
do a fingerprint scanner scam of their own. They decided
to see if they could fool one. And this one
was a little different. It wasn't just an optical scanner.
It was supposed to also detect sweat from pores in
the fingertips. Okay, so so you can't just use a
(16:21):
lump of plato or photograph. You have to have something
that sweats has to have to otherwise it's never gonna work.
So what did they do. They made a latext copy
of a fingerprint and then they did a very sophisticated
thing in order to simulate sweat. Yeah, and it worked.
So if you can't play dough it, lick it, I
(16:45):
guess is the moral of that story. I think I
think that that's really what we all should learn from
this today. Probably, So anyway, they're still seeing this kind
of technology being rolled out, but it's not just an
optical scanners, and even optical skins have gotten a lot
better than they were back in two thousand and five.
So we're gonna we're gonna cover exactly how they work.
(17:05):
But before we do that, let's take a quick break
to thank our sponsor. Alright, I had just talked about
optical scanners, and those are one of the ones that
are the easiest to explain and uh and fairly common
even today. In fact, not my work computer, but my
home computer has in my home laptop has a little
optical scanner. So if I want to log in, I
(17:27):
can just swipe my finger across it. So optical scanners
use something that is found in digital cameras and camcorders
called a charge coupled device or c c D. Now,
essentially that's a light sensor. It's got an array of
things called photo sites. Now that's light sensitive diodes, and
it's works pretty much the way you would imagine. So photons,
(17:49):
those little particles of light when they make a collision
with these photo sites, it generates a little electrical signal
and those can then be compiled and converted into a
digital image. And it's essentially the same process that digital
cameras used to take pictures. And here's the thing though,
So if I put my finger on an optical scanner,
(18:09):
I'm actually blocking light. And unless you happen to be
et the extraterrestrial, your finger probably isn't emitting light. So
how the heck is it getting this picture? Well, it
uses a flash, yeah, except in this case of flash
is probably like a single LED or for some scanners
maybe an array of LEDs light emitting diodes in other words,
(18:31):
and so that provides the light that is necessary to
take this image. And uh, then the c c D
creates an image of your fingertip. However, it's a little funky.
It's inverted, right. The dark areas are going to represent
the ridges that the raised portions of your fingertip, and
the light areas are going to represent the values. Yeah,
so it's kind of like looking at a negative, a
(18:52):
photo negative. Uh. And it makes sense because stuff that's
reflecting more light is going to create a lot a
bigger electra called signal bus creating that. You know, the
charge couple device is going to make that into a
darker portion the valleys. The light is not as much
of it's going to reflect back, so you get a
weaker electrical signal. That's why it gets lighter. Uh So,
(19:15):
if you were to scan your finger and UM and
it tells you that it's a good scan, because most
of these devices also have some sort of fail safe
in them that will alert you if there wasn't enough
enough differentiation between the dark and light parts, right, that
the same way that you're that your camera UM sometimes
will take a picture that's that's overdeveloped or underdeveloped, the
(19:38):
same thing can happen here. Yeah, So if you wanted to,
like if you most of the software has let error
function built into it, so it can tell and it
will ask you to scan again, right, So then you
would scan again. So if it's the first time you're
using it, then you would also end up creating a
profile in some way. It might not be you, it
might be an administrator, but something that links the fingerprint
(19:58):
to who you are and what says you are supposed
to have will happen then on subsequent uses, what will
happen is that when you scan your finger it will
go through its database of of identities that have fingerprints
attached to them look for you. If you're there, then
it will authorize you for whatever use you're allowed. So,
(20:18):
for instance, on my home computer, I've given myself very
strict restrictions because I am not to be trusted. Uh,
And so all I'm able to do is play a
pirated copy of Flappy Bird. That's not true, I don't
have Flappy Bird. But at any rate, you know that's
the basic You know, that's the basic procedure, right, and
(20:40):
and so if your finger print is not found in
that database, you get an error. So either you have
to swipe it again or or scan it again if
it's not swipe all depends on what kind of scanner
you're at, or you end up saying the jig is up,
you got me, I don't really belong here, and then
you run away. Um. So that that's the basic thing,
(21:02):
and what they're looking for. It's not the entire pattern
of your fingertip. It's looking for for a specific minutia
about it. Uh. Certain types of patterns and it and
it depends on the software that the scanner is using.
Um it might be the places where the ridges converge
um or or split apart at the end, or um
(21:22):
any any other kind of detail. It's going to be
unique to you. Right. So in other words, all has
to do is say, hey, there are these three points
on this fingertip, uh that are unique that that's all
I'm concerned about. And if the fingerprint that scan has
those three points, I know it's this person and they
can be let through by constraining on the minutia, then
you really cut down on all the rest of the
(21:43):
data that's necessary to have a verification. Right, you can
kind of throw everything else out and concentrate on that
and right. Uh And and they're pretty good, like we said,
though they can sometimes be fooled by a really high
quality picture of a fingerprint. Right. So what if you
instead of looking at a picture, you were to measure
the fingerprint in some other way, such as capacitance right,
(22:08):
because capacitense touch screens are totally a thing. Yeah, so
it's very similar to what a regular capacityans touch screen is.
So you know, there are different ways of doing touch
screens as well. There's somewhere you have to use pressure.
With the benefit of that is you could be wearing
gloves and still work a pressure version. The downside is
that when people are expected to apply pressure to delicate material,
(22:30):
they sometimes destroy it completely, right, or it'll at least
decrease the lifespan of that object by quite a bit. Capacitance, however,
uses weak electric fields, So when you make contact with
a screen, a touch screen, that's using capacitance. Uh see,
you're a conductor. I don't mean that you conduct trains,
(22:53):
Nor do I mean that you Maybe you do. Maybe
you do, Maybe you do. Maybe you conduct orchestras. Maybe
you conduct orchestras on a train. I don't know, but
I know what I'm talking about. If you do, call us,
because that sounds fascint, would be kind of cool. Actually,
But now I'm talking about electrical conductivity. So we can
conduct electricity. It's not great for us to have a
lot of it, but tiny amounts don't hurt us. Sure,
(23:14):
And as it turns out, the ridges and valleys on
your fingers conducts slightly different amounts of electricity. This blows
my mind. I mean to think that the raised parts
of your fingerprint, and the valleys of your fingerprint are
distinct enough to create a measurable difference in capacitance. You know,
It's something I never would have imagined. And it's really
(23:35):
a sensor issue here. I mean the fact that we
can create these these cells, these capacitor plate cells that
are sensitive enough to tell that yeah technology. So what's
happening is when you put your finger down on one
of these capacity scanners, you are actually you're acting as
a capacitance plate, right, your fingertip is acting is one,
and you already have other ones inside the scanner itself,
(23:58):
and it will end up creating voltages and there will
be difference differences in those voltages. The differences between the
ridges and the valleys based on how far away they
are from the from the cells. Yeah, so if it's
a valley, it's going to be lower capacitance because the
distance is greater. Capacitance is very dependent upon distance. So
if you move to capacitance plates far enough apart, they
(24:20):
will not be they will not work together. So it's
amazing that the valleys, just by being that much further
away will create a different voltage than the ridges. And
then having a whole whole set of these cells set
up next to one another. UM it allows the scanner
to to sort of make a digital picture of your fingerprint,
but just using electricity rather than light. The data from
(24:43):
each one is again compiled and then converted into an
image of sorts. Yeah. Yeah, you can think of it
as like an image made with electricity. And this is
the sort of scanner that the iPhone five S uses,
so it's not an optical scanner. One of the big
benefits of this technolog g is that it's easier to
make it really compact and manaturized, which is why you
(25:04):
could find it in things like handheld electronics, right sure. Um. However,
this technology can also be fooled UM sometimes by by
mold of a finger UM or if someone has gone
and calibrated the scanner to look for things like like
heat or a pulse. UM. You can you can use
one of those movie tricks, like a gelatine or silicone
(25:25):
mold of a finger UM pasted onto a different different finger. Yeah.
My favorite version of getting past a UM capacitance or
an optical scanner is to use the finger that's been
removed from the person who had the authorization. Yeah, yeah, sniping,
that's that's that's your favorite. That's my favorite out in
(25:46):
the field. That's what you like. We had this discussion
about the born identity before we came into the podcast.
This is totally true. Uh, I don't like to discuss
my actual field operative kind of mentality and strategies, but yes,
I do love doing that. So thermal scanners, well, this
one's a little different because it's a it's a heat scanner,
and again it's one of those ideas where it measures
(26:08):
the differences in heat between ridges and valleys. Once again,
you're going to get a slightly higher temperature from the
ridges than you do with the valleys. The valleys that
are essentially pockets of air. There's some downside with this one.
One of the problems with thermal scanners is that if
you if it takes too long to do the scan,
the temperature differences are going to equalize across the and
(26:32):
wind up you just get a blank fingerprint, like a
big blank fingerprint. Not useful. This next one is super cool.
It's ultrasonic ultrasonic sensors, so right, Yeah, we did a
whole episode about ultrasound called How Ultrasound Works. Crazily enough
that published on January if you would like to hear
(26:53):
all about how this technology works. But um, but it's
essentially echolocation. Yeah, you're sending out sound signals and then
you're waiting for them to bounce back, and by measuring
the amount of time it took to go out and
come back, you get an idea of how far away
something is. Well, that works, you know, in lots of
different ways, including being able to tell a fingerprint, being
able to read a fingerprint. It can go even deeper
(27:16):
than that, exactly, it can go into tissues. So if
you wanted, you could create an ultrasonic fingerprint scanner that
scan not just the fingerprint itself, but the underlying veins
that are in your finger which also are going to
be unique to you. So that's a lot harder to
fake than a fingerprint. Like you're not going to get
a really high resolution image of veins and then create
(27:38):
a fake finger easily. It would be really difficult. I mean,
but you could use, um your favorite application, which is
removing someone's finger and that right unless you had also
built into the software to detect living tissue, because to
see if blood is moving through the veins the vessel.
If it's not detecting blood, it's good to say, y'all,
(27:59):
this is messed up. You need to send someone down
right now. The fingerprint scanner. Things that are bad are happening.
That's exactly what the voice it uses too. I I
assumed I run into it in the field all the time.
So yeah, I mean this is uh, you know, that's
we're making light of it because to be serious about
it is so squeaky. But at any rate, it does
(28:20):
mean that you can build those sort of parameters in
so it's not just looking at the fingerprint and the
veins underneath, but also to make sure it is truly
a valid uh entry, so that they don't you know,
you don't end up compromising security. Um and there there's
also I wanted to mention very briefly the difference between
those static uh fingerprint scanners, especially the optical ones where
(28:42):
you just hold your finger down and you wait for it.
It's kind of like a copier, right right, and the
swipe style that you were talking about having on your
home laptop exactly. So if you've ever had a laptop
or any other device that has like a narrow window
and you're supposed to swipe your finger across that window.
The reason for that is that it's actually taking in
a series of quote unquote images of your finger. However,
(29:04):
the implementation is actually being used. It's it's doing then
a quick series. Machines are really fast, so they can
do this without any real problem. They're looking for those
minutia that we talked about before, and they're able to,
uh to use software to compile them. But you know,
it's it's it's nifty having the smaller form factor because
like we said, uh, then you can miniaturize, you can
(29:26):
put them in something like a cell phone and also
make them cheaper. Exactly. Yeah, you've got this little window
and your finger moves past the window instead of the
window having to be big enough to So it's it's
really uh an interesting development and uh pretty cool. Also,
we can mention that biometric systems, many of them, not
necessarily all of them, but many of them end up
(29:48):
translating your fingerprint into an algorithm that or an algorithm
rather does the translating that turns it into a bunch
of ones and zeros, all right, right. A digitization um
sometimes called a hash. It's like a personal code like
a really long pen. Yeah. So in this case, what
you would say is that it's not storing an image
of your fingerprint. It's not like if you were to
somehow hack into the computer you would suddenly see a
(30:10):
on your screen representation of your fingerprint. It would just
mean that it would take the the pattern of ridges
and valleys and all the night nutia convert that into
this this hash, this this long string of ones and zeros,
and the next time you scan it, if the if
the same hash comes up, then it as a match
and it says, all right, identification has been verified. But
(30:32):
it's not actually like an actual, real image of your fingerprint.
And the reason why a lot of these companies try
to talk about you know this as as a big
selling point is that it doesn't allow you to recreate
a person's fingerprint if you were to get hold of
those hashes. So it's not like you would say, oh,
if I just put this through an image program, I
(30:55):
suddenly get a picture of that fingerprint. You would just yeah,
that's that's the way I think that the iPhone five
S and the Galaxy something something that the latest Samsung
incorporates it, and um PayPal, these Days even has um
fingerprint signatures on their app, and any any device that
(31:15):
allows you to in to scan in your fingerprint will
let you pay for stuff on PayPal with that signature.
I'm sure we're going to see a lot of that
kind of stuff incorporate with things like the NFC technology
or even the low Bluetooth energy low energy Bluetooth. Rather,
I should say, uh, implementations where your fingerprint instead of
having to put in a pen, you just swipe your
(31:36):
finger Yeah, you know, I don't know. I kind of
hope that it's an additional safety feature, not a standalone
safety feature, because you know, unlike a password or a pin,
you can't just change your fingerprint if it gets stolen,
and this hash issue adds security to to the whole thing.
It's harder to but I'm sure that someone if they
really wanted to, could decode a hash and figure out
(31:58):
what that scan looks like. Yuh maybe, I mean, they
would have to have a lot of information, but it
is It is important to say that there is no
security feature out there that's going to be perfect, right right,
There's nothing out there, so having it as an additional tool,
I agree, Lauren, that's that's the best way of looking
at it. I think anytime we decide that we're going
(32:20):
to rely on a specific implementation and that's it and
we're done, we're good, then we're pretty much dooming ourselves
to getting hacked in some way down the line because
people are smart and they figure out ways around rules
they do, and I really don't want to have to
change my fingerprints, not again. All right, So that wraps
up this episode of tex Stuff. Folks, if you have
(32:41):
suggestions for future topics, you should let us know because
otherwise we're just gonna keep doing what we're doing. Let
us know by sending us an email. Our address it's
text Stuff at Discovery dot com, or drop us a
line on Facebook, Twitter or Tumbler. Our handle is tech
Stuff hs W, and we will talk to you again
really soon for more on this and thousands of other
(33:06):
topics because it how stuff works dot Com
Get in touch with technology with text Stuff from how
Stuff Work dot com. Either everyone, and welcome to Text Stuff.
I'm Jonathan Strickland and I'm La. And you know, we
had to actually verify our identities before walking into the podcast,
which is just standard operating procedure here in How Stuff Works.
(00:25):
Oh right, it's a it's a blood sample, retina scan,
and fingerprint before we're allowed to enter any doors. Yeah,
it's really awkward. That's why most of us no longer
wait till the last minute to have to run to
the bathroom because disaster can strike. But it does mean
that we thought, hey, we should talk about biometrics, and
then we started looking into it and getting really excited,
and then we realized, hey, there's a lot to talk about, right. Biometrics,
(00:51):
of course, being the measurable biological or behavioral characteristics used
for for any given individual. Yes, this is what how
the FBI says, this is what the biometrics are. So, uh,
you know, it's one of those things where we knew
it was a huge topic and we decided to narrow
it down. So today we're specifically focusing on your fingerprints,
(01:14):
well not your fingerprints, I mean, I mean everyone's fingerprints. No,
see the person sitting next to you, No, not that one,
the other one, that person's fingerprints. That's that's the one
we're concentrating on. So yeah, because everyone has has different fingerprints,
I mean like everyone, right, And this is something that
has been known for a while but then forgotten and
then rediscovered. So we're going to talk about that because
(01:35):
it's kind of funny. So these days we think of
biometrics as sort of those automated ways to verify your
identity based on some sort of biological characteristic, like you know,
the eye scan or the fingerprints scan or whatever. Vocal
scans as well, you know, like the voice imprint. Lots
of different Hollywood versions of this. But you know, again,
(01:56):
going into that fingerprint approach, we thought that, you know,
we we look at not just how we've defined it
and how stuff works, but look at a whole history
of fingerprinting. U We're not the first podcast to do this,
by the way, certainly not. Josh and Check of Stuff
you Should Know did an episode on April called how
(02:16):
Fingerprinting Works, and they go pretty deeply into the history
and say many pithy things. So if you would like
to check that episode out. You can go to Stuff
you Should Know dot com right and just stick around
because we're gonna say some pithy things too. We are
going to cover some of the history, kind of a
quick overview. But first I thought I would read a
couple of little excerpts from our article on how fingerprint
(02:38):
scanners work, because there are a couple that I thought
were really interesting from how stuff Works dot Com. Neither
of us actually wrote this. Nope, Nope, I didn't write
this one. This one says people have tiny ridges of
skin on their fingers because this particular adaptation was extremely
advantageous to the ancestors of the human species. The pattern
of ridges and valleys on fingers make it easier for
(02:59):
the ends to grip things in the same way a
rubber tread pattern helps to attire grip the road. The
other function of fingerprints is a total coincidence. Like everything
in the human body, these ridges form through a combination
of genetic and environmental factors. The genetic code and DNA
gives general orders in the way skin should form in
the developing fetus, but the specific way it forms is
(03:21):
a result of random events. The exact position of the
fetus in the womb at a particular moment, and the
exact composition and density of surrounding amniotic fluid decides how
every individual ridge will form. This, by the way, is
how identical twins can have different fingerprints. Pretty cool because
you know, genetically they're identical, but their fingerprints are different,
(03:42):
still different. Interesting. So looking at this history, you might think, Okay,
I've heard about fingerprinting, particularly when it applies to law enforcement.
That's probably where a lot of people are familiar with it.
Besides the verification. Sure, sure, and uh and a couple
popular media pieces have talked recently about Um. I mean
(04:02):
you you get things like Ripper Street or Sleepy Hollow
having characters going like this new fingerprinting thing in the amazing,
amazing age of Victoria. Um, not not so much. Actually,
so fingerprints people, Well, first of all, people have been
aware of them for ages because we're curious folks, you know,
human beings. We we were very curious and narcissistic. We
(04:24):
like to learn stuff, and we like to look at ourselves.
And how do I know that this dates back? Are
ages and ages and ages ago because we have prehistoric
depictions found in Nova Scotia uh, and it depicted a
hand with ridge patterns on the skin. Now, that does
not mean that the ancient Nova Scotians were familiar with
(04:46):
the fact that all the fingerprints were unique and therefore
no two individuals had the same ones, but at least
show that, you know, yeah, they noticed them. Yeah, but
the ancient Babylonians may have actually used ping of prints
to differentiate people. Um, we've found fingerprints in clay to
to sign business transactions, and the ancient Chinese used inked
(05:08):
fingerprints for both business purposes and child identification. And in
the thirteen hundreds in Persia, official government documents often included fingerprints,
probably to indicate they were authorized and official. Now, according
to the US Marshall's Office, which has an entire web
page devoted to fingerprinting in the history of it, one
(05:28):
government official in Persia at that time made the observation
that no two fingerprints were alike, which obviously would be
very important if you're making a document official or authorized.
But it wasn't until the eighteen eighties that that amazing
Age of Victoria previously mentioned that we got some kind
of official classification system, right. It wasn't until the modern
(05:50):
era that we started seeing it in UH story. It
wasn't even in wide use at the beginning. It was
just kind of exploratory. Dr. Henry Faulds back in eighteen
eighty posed using fingerprints for identification as well as a
means of classifying them. So he forwarded these ideas to
a certain Charles Darwin, very important historical figure in his
(06:12):
own right. But Darwin at the time was towards the
end of his life and felt that he did not
have the necessary UH time and energy to devote to
this thought. It was really interesting, however, so he forwarded
the information along to a cousin of his named Francis Galton.
So false would write a scientific paper about his methods
and actually identified a fingerprint. Ascertain the identity of the
(06:36):
person who left that fingerprint on bottle of alcohol shouldn't
come as any surprise. I guess who brings it all together?
It does. Then in three Mark Twain would would use
this this new startling scientific information in a story. Yeah,
it was in Life on the Mississippi, and in that
(06:58):
one of the elements of that stories of order is
identified through the use of fingerprints. And he would revisit
the idea in a book called Putting Head Wilson. Putting
Head Wilson. Yea, so it's interesting. Now this was before
anyone was actually using uh, fingerprints in any kind of
criminal investigations on an official basis. It had not been
(07:19):
science fiction, really was it kind of was so so
that was exciting. But but soon in eighteen eighty eight,
Sir Francis Galton, remember the cousin to Charles Darwin, who
had received information about this about ten years previous, um
began his own study of fingerprints. Yep. He wrote a
book in eighteen ninety two and put forth a formal
classification system and identify the tiny characteristics used to differentiate fingerprints,
(07:44):
which now we call Galton's details. He also observed that
fingerprints don't change over the lifetime of a person, so
the ones you have when you're a kid are the
same ones you have when you're old. Originally wanted to
kind of link fingerprints to certain types of traits like
intelligence or heredity, which is so racist. Yeah, kind of essentially,
(08:06):
I think this was almost in an attempt. And I
don't know enough about Galton to say this for sure,
but it seems like an attempt to justify certain society's
beliefs in certain people, that kind of thing. Yeah, it
wasn't necessarily so racist, but um, but it's kind of
it kind of runs in that direction. Yeah, because I mean,
the idea that you could identify a person's intelligence based
(08:28):
on their fingerprints already seems a little sketchy, And in fact,
he did determined that there was no connection. There was
no there were no identifier marks in a person's fingerprints
that would give you any clue as to that person's
intelligence or genetic background. However, he did figure out that
there were a lot of differences and that people didn't
(08:48):
weren't likely to have the same fingerprints. Yeah, unlikely, in
the order of one in sixty four billion, that's pretty unlikely.
So in eight we get the first use of fingerprints
in a criminal investigation on an official level. Uh one vs.
Tech And I'm sure I butchered his last name. Who
(09:10):
was a police officer in Argentina used them in a
murder investigation. It was actually a really tragic case, but
the discovery meant that he was able to solve this
mystery and prove that the person that was believed to
have been the murderer was in fact not the killer.
So Uh, not only was it the first use, but
(09:32):
it was a pretty dramatic example of it. Now, between
we're gonna skip to nineteen eighteen, but between the late
nineteenth century and the early twentieth century he started to
see fingerprints get adopted into various legal organizations all around
the world. The United Kingdom and the United States were
leading the way, but it was all over the place.
(09:53):
So by nineteen eighteen you have Edmund Lekard who says
that you only need twelve points of similarity between an
individual's fingerprint and a target fingerprint to serve as a
positive identification. Now you may have heard about those twelve
points of singularity, that this is somehow like a legal thing,
that if you were able to meet those twelve points
(10:14):
of singularity, you have the legal basis to say this
person did this. Uh, not necessarily a legal definition at all.
In fact, UH, countries have very very different ways of
saying whether or not a fingerprint is a valid match
for another one, and some, like the United States, do
(10:34):
not have a minimum number of resemblances that need to
be there in order for you to call it a match. Now,
usually law enforcement agencies rely on experts who give their
expert opinion and therefore putting their own reputation on the
line as to whether or not something matches. And of
course now these days we rely very heavily on digital information,
(10:56):
which with very very complex and intelligent i'll rhythms, that
will that will do some really interesting like work. Yeah,
and so with that, you know, the the level of
a confidence grows quite a bit. So, uh, just so
you know that twelve points of similarity not necessarily a
legal standard. Nineteen four, that's when Congress enabled had an
(11:18):
act that established the new division for the Federal Bureau
of Investigation also known as the f b I. UH
and this division was called the Identification Division. I bet
you can guess what it did. So it became kind
of a centralized fingerprint file for the entire country. So
not it wasn't necessarily uh standard procedure for every law
(11:39):
enforcement agency out there to send a copy to the FBI.
But that's kind of what started to happen, so that, uh,
there could be this sort of cooperation between different departments
which often wouldn't have any communication with each other. Sure sure,
by ninety six, the FBI would have processed more than
a hundred million fingerprint cards. Yeah, not just processed, but
(12:02):
they did that by hand, right, right, and it would
be two million by two million physical cards with fingerprints
on them. I mean, just imagine how many, Like how
how much storage you need just for me? It's two
I can't even I can't even imagine it. But by
the FBI introduced the Integrated Automated Fingerprint Identification System or
(12:27):
if SO. It's the largest fingerprint database in the world,
and its computer automated. It takes about twenty seven minutes
for the system to comb through every single file in
its database to find out if there is a potential match.
During a criminal investigation, it's different. If it's a civil case,
it's actually like more than an hour. But for criminal investigation,
(12:50):
for all the criminal files that are storing this database,
twenty seven minutes from the time you actually input the
suspects fingerprint. I imagine that's a lot faster than whatever
in her and they sent down to the basement, Well yeah,
because I mean you would have to narrow down the
person quite a bit before you could ever start coming right,
(13:10):
this is a man, So cut out all the women
and then go like there are seventy million of them
down there. Uh yeah, that would be that would be
a daunting task. So in the digital age, we can
actually analyze this stuff way better than we ever could,
Like you don't have to use the naked eye anymore
and try and find those little ridges and stuff. You
(13:30):
can actually rely very heavily upon computer systems. And once
we started getting those computer systems in place, they pretty
soon thereafter became um commercially available. Yeah. Yeah, we had
some fingerprint verification systems that have been around for a
few decades now. On the consumer level, they've only been
available fairly recently. And you might be thinking, oh, yeah, yeah,
(13:53):
the iPhone five s because it has that that fingerprint
scanner where you can use that to log into your phone.
That's the first smart ohne to ever use that, right, Nope, no, no,
there's actually a mobile device. The first mobile device that
I found was a one that dated from two thousand three,
the H and Boy. The name of this is phenomenal.
HP names their products in such catchy ways. It's the
(14:15):
HP I pack, I p a Q P PC pocket PC.
Oh yeah, it just rolls off the tongue. Yeah, it
really is. I mean, with a name like that, how
could you resist I phone my phone. So at any rate,
this was the first mobile device to incorporate finger scanning technology.
(14:37):
But it was also sort of the edge of a
boom for the technology. UM it was being extended for
for wide consumer use at the time. I mean, you know,
keyboards and mice had UM, laptops had him. You can
buy a USB scanner for multipurpose use and encrypt everything
with your fingerprint, right, you could end up creating, for example,
with a copier, you could end up telling people, all right,
(14:57):
this group of folks are authorized to make copy. Anyone
who's not on this list cannot make copies. And you
would walk up to make copies. And if you weren't
on that list, then I guess no fun Christmas party
Shenanigans for you. But but but but also opening this up
to the consumer market meant that a lot of people
started finding the flaws in the technology. Oh yes. In
(15:18):
December five, clarks And University researchers announced that they could
fool of the world's fingerprint scanners using an incredibly sophisticated,
expensive substance. Yeah, they could just go out to toy
store and buy some Plato and essentially make a copy
(15:38):
of a fingerprint and put it on any optical scanner,
and we'll talk about the optical scanners in a little bit.
And it worked really well. So that gave people some
pause and thought, maybe we should come up with something
besides optical scanners too, because fingerprint identification is a great idea.
But if it's if it's that easy to fool, we
have to find a different way of measuring it. So
(16:00):
then there was a totally different expose on September twenty one,
two thousand and six, when our beloved MythBusters decided to
do a fingerprint scanner scam of their own. They decided
to see if they could fool one. And this one
was a little different. It wasn't just an optical scanner.
It was supposed to also detect sweat from pores in
the fingertips. Okay, so so you can't just use a
(16:21):
lump of plato or photograph. You have to have something
that sweats has to have to otherwise it's never gonna work.
So what did they do. They made a latext copy
of a fingerprint and then they did a very sophisticated
thing in order to simulate sweat. Yeah, and it worked.
So if you can't play dough it, lick it, I
(16:45):
guess is the moral of that story. I think I
think that that's really what we all should learn from
this today. Probably, So anyway, they're still seeing this kind
of technology being rolled out, but it's not just an
optical scanners, and even optical skins have gotten a lot
better than they were back in two thousand and five.
So we're gonna we're gonna cover exactly how they work.
(17:05):
But before we do that, let's take a quick break
to thank our sponsor. Alright, I had just talked about
optical scanners, and those are one of the ones that
are the easiest to explain and uh and fairly common
even today. In fact, not my work computer, but my
home computer has in my home laptop has a little
optical scanner. So if I want to log in, I
(17:27):
can just swipe my finger across it. So optical scanners
use something that is found in digital cameras and camcorders
called a charge coupled device or c c D. Now,
essentially that's a light sensor. It's got an array of
things called photo sites. Now that's light sensitive diodes, and
it's works pretty much the way you would imagine. So photons,
(17:49):
those little particles of light when they make a collision
with these photo sites, it generates a little electrical signal
and those can then be compiled and converted into a
digital image. And it's essentially the same process that digital
cameras used to take pictures. And here's the thing though,
So if I put my finger on an optical scanner,
(18:09):
I'm actually blocking light. And unless you happen to be
et the extraterrestrial, your finger probably isn't emitting light. So
how the heck is it getting this picture? Well, it
uses a flash, yeah, except in this case of flash
is probably like a single LED or for some scanners
maybe an array of LEDs light emitting diodes in other words,
(18:31):
and so that provides the light that is necessary to
take this image. And uh, then the c c D
creates an image of your fingertip. However, it's a little funky.
It's inverted, right. The dark areas are going to represent
the ridges that the raised portions of your fingertip, and
the light areas are going to represent the values. Yeah,
so it's kind of like looking at a negative, a
(18:52):
photo negative. Uh. And it makes sense because stuff that's
reflecting more light is going to create a lot a
bigger electra called signal bus creating that. You know, the
charge couple device is going to make that into a
darker portion the valleys. The light is not as much
of it's going to reflect back, so you get a
weaker electrical signal. That's why it gets lighter. Uh So,
(19:15):
if you were to scan your finger and UM and
it tells you that it's a good scan, because most
of these devices also have some sort of fail safe
in them that will alert you if there wasn't enough
enough differentiation between the dark and light parts, right, that
the same way that you're that your camera UM sometimes
will take a picture that's that's overdeveloped or underdeveloped, the
(19:38):
same thing can happen here. Yeah, So if you wanted to,
like if you most of the software has let error
function built into it, so it can tell and it
will ask you to scan again, right, So then you
would scan again. So if it's the first time you're
using it, then you would also end up creating a
profile in some way. It might not be you, it
might be an administrator, but something that links the fingerprint
(19:58):
to who you are and what says you are supposed
to have will happen then on subsequent uses, what will
happen is that when you scan your finger it will
go through its database of of identities that have fingerprints
attached to them look for you. If you're there, then
it will authorize you for whatever use you're allowed. So,
(20:18):
for instance, on my home computer, I've given myself very
strict restrictions because I am not to be trusted. Uh,
And so all I'm able to do is play a
pirated copy of Flappy Bird. That's not true, I don't
have Flappy Bird. But at any rate, you know that's
the basic You know, that's the basic procedure, right, and
(20:40):
and so if your finger print is not found in
that database, you get an error. So either you have
to swipe it again or or scan it again if
it's not swipe all depends on what kind of scanner
you're at, or you end up saying the jig is up,
you got me, I don't really belong here, and then
you run away. Um. So that that's the basic thing,
(21:02):
and what they're looking for. It's not the entire pattern
of your fingertip. It's looking for for a specific minutia
about it. Uh. Certain types of patterns and it and
it depends on the software that the scanner is using.
Um it might be the places where the ridges converge
um or or split apart at the end, or um
(21:22):
any any other kind of detail. It's going to be
unique to you. Right. So in other words, all has
to do is say, hey, there are these three points
on this fingertip, uh that are unique that that's all
I'm concerned about. And if the fingerprint that scan has
those three points, I know it's this person and they
can be let through by constraining on the minutia, then
you really cut down on all the rest of the
(21:43):
data that's necessary to have a verification. Right, you can
kind of throw everything else out and concentrate on that
and right. Uh And and they're pretty good, like we said,
though they can sometimes be fooled by a really high
quality picture of a fingerprint. Right. So what if you
instead of looking at a picture, you were to measure
the fingerprint in some other way, such as capacitance right,
(22:08):
because capacitense touch screens are totally a thing. Yeah, so
it's very similar to what a regular capacityans touch screen is.
So you know, there are different ways of doing touch
screens as well. There's somewhere you have to use pressure.
With the benefit of that is you could be wearing
gloves and still work a pressure version. The downside is
that when people are expected to apply pressure to delicate material,
(22:30):
they sometimes destroy it completely, right, or it'll at least
decrease the lifespan of that object by quite a bit. Capacitance, however,
uses weak electric fields, So when you make contact with
a screen, a touch screen, that's using capacitance. Uh see,
you're a conductor. I don't mean that you conduct trains,
(22:53):
Nor do I mean that you Maybe you do. Maybe
you do, Maybe you do. Maybe you conduct orchestras. Maybe
you conduct orchestras on a train. I don't know, but
I know what I'm talking about. If you do, call us,
because that sounds fascint, would be kind of cool. Actually,
But now I'm talking about electrical conductivity. So we can
conduct electricity. It's not great for us to have a
lot of it, but tiny amounts don't hurt us. Sure,
(23:14):
And as it turns out, the ridges and valleys on
your fingers conducts slightly different amounts of electricity. This blows
my mind. I mean to think that the raised parts
of your fingerprint, and the valleys of your fingerprint are
distinct enough to create a measurable difference in capacitance. You know,
It's something I never would have imagined. And it's really
(23:35):
a sensor issue here. I mean the fact that we
can create these these cells, these capacitor plate cells that
are sensitive enough to tell that yeah technology. So what's
happening is when you put your finger down on one
of these capacity scanners, you are actually you're acting as
a capacitance plate, right, your fingertip is acting is one,
and you already have other ones inside the scanner itself,
(23:58):
and it will end up creating voltages and there will
be difference differences in those voltages. The differences between the
ridges and the valleys based on how far away they
are from the from the cells. Yeah, so if it's
a valley, it's going to be lower capacitance because the
distance is greater. Capacitance is very dependent upon distance. So
if you move to capacitance plates far enough apart, they
(24:20):
will not be they will not work together. So it's
amazing that the valleys, just by being that much further
away will create a different voltage than the ridges. And
then having a whole whole set of these cells set
up next to one another. UM it allows the scanner
to to sort of make a digital picture of your fingerprint,
but just using electricity rather than light. The data from
(24:43):
each one is again compiled and then converted into an
image of sorts. Yeah. Yeah, you can think of it
as like an image made with electricity. And this is
the sort of scanner that the iPhone five S uses,
so it's not an optical scanner. One of the big
benefits of this technolog g is that it's easier to
make it really compact and manaturized, which is why you
(25:04):
could find it in things like handheld electronics, right sure. Um. However,
this technology can also be fooled UM sometimes by by
mold of a finger UM or if someone has gone
and calibrated the scanner to look for things like like
heat or a pulse. UM. You can you can use
one of those movie tricks, like a gelatine or silicone
(25:25):
mold of a finger UM pasted onto a different different finger. Yeah.
My favorite version of getting past a UM capacitance or
an optical scanner is to use the finger that's been
removed from the person who had the authorization. Yeah, yeah, sniping,
that's that's that's your favorite. That's my favorite out in
(25:46):
the field. That's what you like. We had this discussion
about the born identity before we came into the podcast.
This is totally true. Uh, I don't like to discuss
my actual field operative kind of mentality and strategies, but yes,
I do love doing that. So thermal scanners, well, this
one's a little different because it's a it's a heat scanner,
and again it's one of those ideas where it measures
(26:08):
the differences in heat between ridges and valleys. Once again,
you're going to get a slightly higher temperature from the
ridges than you do with the valleys. The valleys that
are essentially pockets of air. There's some downside with this one.
One of the problems with thermal scanners is that if
you if it takes too long to do the scan,
the temperature differences are going to equalize across the and
(26:32):
wind up you just get a blank fingerprint, like a
big blank fingerprint. Not useful. This next one is super cool.
It's ultrasonic ultrasonic sensors, so right, Yeah, we did a
whole episode about ultrasound called How Ultrasound Works. Crazily enough
that published on January if you would like to hear
(26:53):
all about how this technology works. But um, but it's
essentially echolocation. Yeah, you're sending out sound signals and then
you're waiting for them to bounce back, and by measuring
the amount of time it took to go out and
come back, you get an idea of how far away
something is. Well, that works, you know, in lots of
different ways, including being able to tell a fingerprint, being
able to read a fingerprint. It can go even deeper
(27:16):
than that, exactly, it can go into tissues. So if
you wanted, you could create an ultrasonic fingerprint scanner that
scan not just the fingerprint itself, but the underlying veins
that are in your finger which also are going to
be unique to you. So that's a lot harder to
fake than a fingerprint. Like you're not going to get
a really high resolution image of veins and then create
(27:38):
a fake finger easily. It would be really difficult. I mean,
but you could use, um your favorite application, which is
removing someone's finger and that right unless you had also
built into the software to detect living tissue, because to
see if blood is moving through the veins the vessel.
If it's not detecting blood, it's good to say, y'all,
(27:59):
this is messed up. You need to send someone down
right now. The fingerprint scanner. Things that are bad are happening.
That's exactly what the voice it uses too. I I
assumed I run into it in the field all the time.
So yeah, I mean this is uh, you know, that's
we're making light of it because to be serious about
it is so squeaky. But at any rate, it does
(28:20):
mean that you can build those sort of parameters in
so it's not just looking at the fingerprint and the
veins underneath, but also to make sure it is truly
a valid uh entry, so that they don't you know,
you don't end up compromising security. Um and there there's
also I wanted to mention very briefly the difference between
those static uh fingerprint scanners, especially the optical ones where
(28:42):
you just hold your finger down and you wait for it.
It's kind of like a copier, right right, and the
swipe style that you were talking about having on your
home laptop exactly. So if you've ever had a laptop
or any other device that has like a narrow window
and you're supposed to swipe your finger across that window.
The reason for that is that it's actually taking in
a series of quote unquote images of your finger. However,
(29:04):
the implementation is actually being used. It's it's doing then
a quick series. Machines are really fast, so they can
do this without any real problem. They're looking for those
minutia that we talked about before, and they're able to,
uh to use software to compile them. But you know,
it's it's it's nifty having the smaller form factor because
like we said, uh, then you can miniaturize, you can
(29:26):
put them in something like a cell phone and also
make them cheaper. Exactly. Yeah, you've got this little window
and your finger moves past the window instead of the
window having to be big enough to So it's it's
really uh an interesting development and uh pretty cool. Also,
we can mention that biometric systems, many of them, not
necessarily all of them, but many of them end up
(29:48):
translating your fingerprint into an algorithm that or an algorithm
rather does the translating that turns it into a bunch
of ones and zeros, all right, right. A digitization um
sometimes called a hash. It's like a personal code like
a really long pen. Yeah. So in this case, what
you would say is that it's not storing an image
of your fingerprint. It's not like if you were to
somehow hack into the computer you would suddenly see a
(30:10):
on your screen representation of your fingerprint. It would just
mean that it would take the the pattern of ridges
and valleys and all the night nutia convert that into
this this hash, this this long string of ones and zeros,
and the next time you scan it, if the if
the same hash comes up, then it as a match
and it says, all right, identification has been verified. But
(30:32):
it's not actually like an actual, real image of your fingerprint.
And the reason why a lot of these companies try
to talk about you know this as as a big
selling point is that it doesn't allow you to recreate
a person's fingerprint if you were to get hold of
those hashes. So it's not like you would say, oh,
if I just put this through an image program, I
(30:55):
suddenly get a picture of that fingerprint. You would just yeah,
that's that's the way I think that the iPhone five
S and the Galaxy something something that the latest Samsung
incorporates it, and um PayPal, these Days even has um
fingerprint signatures on their app, and any any device that
(31:15):
allows you to in to scan in your fingerprint will
let you pay for stuff on PayPal with that signature.
I'm sure we're going to see a lot of that
kind of stuff incorporate with things like the NFC technology
or even the low Bluetooth energy low energy Bluetooth. Rather,
I should say, uh, implementations where your fingerprint instead of
having to put in a pen, you just swipe your
(31:36):
finger Yeah, you know, I don't know. I kind of
hope that it's an additional safety feature, not a standalone
safety feature, because you know, unlike a password or a pin,
you can't just change your fingerprint if it gets stolen,
and this hash issue adds security to to the whole thing.
It's harder to but I'm sure that someone if they
really wanted to, could decode a hash and figure out
(31:58):
what that scan looks like. Yuh maybe, I mean, they
would have to have a lot of information, but it
is It is important to say that there is no
security feature out there that's going to be perfect, right right,
There's nothing out there, so having it as an additional tool,
I agree, Lauren, that's that's the best way of looking
at it. I think anytime we decide that we're going
(32:20):
to rely on a specific implementation and that's it and
we're done, we're good, then we're pretty much dooming ourselves
to getting hacked in some way down the line because
people are smart and they figure out ways around rules
they do, and I really don't want to have to
change my fingerprints, not again. All right, So that wraps
up this episode of tex Stuff. Folks, if you have
(32:41):
suggestions for future topics, you should let us know because
otherwise we're just gonna keep doing what we're doing. Let
us know by sending us an email. Our address it's
text Stuff at Discovery dot com, or drop us a
line on Facebook, Twitter or Tumbler. Our handle is tech
Stuff hs W, and we will talk to you again
really soon for more on this and thousands of other
(33:06):
topics because it how stuff works dot Com
TechStuff News
Hosts And Creators
Oz Woloshyn
Karah Preiss
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