How is a captcha used
How Does CAPTCHA Work?
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organic or robotic here at Tech quickie
but back on topic odds are you've
probably seen little tests like that
scattered around the internet when
you're trying to post a comment create
an account or buy something there called
CAPTCHAs which stands for completely
automated public Turing tests to tell
computers and humans apart proving once
again that the computer science
community continues to struggle with the
concept of acronyms anyway the irony of
using computing techniques to trick
other computers isn't really new leet
speak which goes all the way back to the
early 1980s originated as a method of
preventing content from being easily
searchable and to work around obstacles
like profanity filters a use that is
still common to this day but modern
CAPTCHA didn't come around until the
late 1990s when the then popular search
engine Alta Vista panelled was trying to
find a way to prevent BOTS or automated
computer programs from adding tons of
spam and malicious URLs to their linked
database they wanted to put some kind of
barrier in place and approach the
problem by thinking about something that
both humans and computers were good at
namely optical character recognition
which you can learn more about here then
introducing elements that made the task
much more difficult for computers while
keeping it fairly easy for humans and
since computers of the day could only
recognize clear easy to read text Alta
vistas engineers forced the user or the
bot as it were to read a puzzle with
distorted misaligned text with stray
marks in order to submit a URL to the
data
bass cool right this form of CAPTCHA
continues to be quite popular along with
audio CAPTCHA for the visually impaired
that in a similar vein typically
includes spoken letters that are
somewhat garbled to defeat automated
sound analysis guy2 w you'll see it
employed in situations ranging from
preventing BOTS from signing up for
social media accounts to cut down on
spam to verification on ticket buying
websites to ensure that BOTS working for
ticket scalpers can't snatch up all the
tickets to popular events you might even
see CAPTCHAs more frequently if you're
using a VPN service as many website
administrators are aware that VPNs are a
popular tool that scammers can use to
conceal their identities so a request
from a known VPN IP address is more
likely to trigger a CAPTCHA prompt but
there's a bit more to it than simply
presenting the scheming bot with a
confusing image capture scripts also
need to be written securely so that the
correct answer isn't available to the
bot through a backdoor for example some
CAPTCHA scripts especially many freely
available ones render the text on the
user's computer instead of on the server
and handle the answer in plain text
meaning that a bot can be written to
steal the answer without ever solving
the puzzle but even if proper security
is implemented bots are also getting a
lot more sophisticated than they used to
be and greater processing power has
enabled them to use machine learning to
get better at solving these kinds of
CAPTCHAs so everything from image
recognition puzzles to trivia questions
have been employed to stay one step
ahead of the spam bot arms race but
Linus what about those prompts that I've
been seeing these days that just say I'm
not a robot and then I just check a box
so I mean couldn't a robot do that how
does that work
well this is a pretty cool mechanism
from Google called no CAPTCHA it
actually tracks your mouse movements
right before you check the box humans
tend to move their mice in Wiggly
imperfect ways when they want to point
it something whereas this behavior is
usually absent with a bot no CAPTCHA
also looks at your IP address and cookie
activity to see if it's probably
consistent with a human instead of a bot
and this automation has made it much
faster and less frustrating for the user
increasing its popularity it's generally
regarded as reliable which is cool but
back to that face I made before it has
privacy advocates concerned about how
much information it's sending to Google
and how exactly is it being used oh that
Google but considering how many people
see an opportunity to make a quick buck
by deploying spam bots as the Internet's
influence continues to grow it isn't
likely we'll see the human verification
arms race cool down anytime soon I just
hope that it doesn't reach the point
where we have to submit like a DNA
sample and like a stool sample just to
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