Download - 3D CAPTCHA 1
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3D CAPTCHAA next generation of the Captcha
-Niriksha shetty
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Contents
1.Origin
2. Introduction
1.1. Characteristics
1.2. Captcha methods
3. Related works
4. Proposed method
5. Results
6. Conclusion
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ORIGIN
F i r s t dev e l oped by A l t a V i s t a i n 1997 . T he
te rm co ined in 2000 by Lu i s von Ahn ,
M a n ue l B l um a n d N i c ho l a s J . H opper o f
Carneg i e Me l lon Un i ve r s i t y and JohnLa n g fo r d o f IB M .
P r i m i t i v e CA PT CH As seem t o ha v e been
dev e l oped i n 1997 by A n dr e i B r ode r , M a r t i n
Abad i , K r i shna Bh ar a t , and Mark L i l l i b r idget o p r ev en t bo t s f r om a dd i n g U R Ls t o t he i r
sea r ch eng ine .
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Introduction
CAPTCHA - Completely Automated Public Turing test to
tell Computers and Humans Apart.
Turing Test is a test for determining whether or not
machine intelligence can converse like a human.
The CAPTCHA is used to keep bots and other automated
programs from signing up for offers, collecting or signing
up for email address, violating privacy, trying to crack
passwords, or sending out spam to unsuspecting email
recipients.
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Introduction
A CAPTCHA is a program that protects websites
against bots by generating and grading tests thathumans can pass but current computer programs
cannot.
It is a type of challenge-response test used in
computing to ensure that the response is notgenerated by a computer.
CAPTCHA requires the user type letters or digits
from a distorted image that appears on the screen.
Any user entering a correct solution is presumed tobe human else user is bot and denied access.
CAPTCHAs rely on difficult problems in artificial
intelligence .
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Characteristics:
A CAPTCHA is a means of automatically generating
new challenges which:
Current software is unable to solve accurately.
Most humans can solve.
Does not rely on the type of CAPTCHA being new
to the attacker.
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Applications
1.)Rediffmail
Overlapping characters.
Noisy background.
Difficult to read.
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Applications
2.) Google
Pure white background.
Single color character.
Different fonts.
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Applications
3.) Hotmail
Sequence of characters.
Easy by human.
Difficult for OCR.
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Applications
4.) Friendster
Many fonts in sequence.
Colorful and easy.
No overlapping.
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Applications
5.) eBay
Only digits.
No background.
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Proposedmethod
To develop a sequence of 3D characters which is easily
recognizable by human but difficult by an OCR.
The basis for a strong OCR-based CAPTCHA is ensuring thatsegmentation is hard.
The CAPTCHA text consists of a total of 6 alphanumeric
characters which are letters and numbers.
Each has its own axis and rotation angle, ranging from -45 to
45 generated using standard randomization function.
CAPTCHA images are generated by using DirectX.
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ProposedmethodFactors affecting the sequence of characters
Rotation.
Overlapping.
Obstacle such as straight line.
Distributed Noise.
Character Colour.
Background Colour.
Scaling.
Font.
Special Character.
Background Texture.
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Proposedmethod - Captcha schemes
Scheme 1:
3D CAPTCHA with rotation.
All characters contain a same
colour.
Each character is rotated in an
individual angle.
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Proposedmethod - Captcha schemes
Scheme 2:
3D CAPTCHA with
overlapping characters.
Characters often cause a
segmentation problem.
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Proposedmethod - Captcha schemes
Scheme 4:
3D CAPTCHA are with
distributed noise of characters.
Reduction of image clarity.
Noise colour is same as the
colour of the character.
Pixel noise is randomly
generated.
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Proposedmethod - Captcha schemes
Scheme 5:
3D CAPTCHA with rotation
and colour background.
Colour of text is generated
randomly, that would contrast
sufficiently with the background
colour, to ensure legibility.
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Proposedmethod - Captcha schemes
Scheme 6:
3D CAPTCHA with rotation
and character colour variation.
Attract user and improve
usability.
Colour is randomly generatedfrom RGB components.
Makes CAPTCHA challenges
interesting.
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Proposedmethod - Captcha schemes
Scheme 7:
3D CAPTCHA with rotation and
character scaling.
Scaling is performed individually
in each axis.
Scale value is randomly selected to
perform a half or double in length.
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Proposedmethod - Captcha schemes
Scheme 8:
3D CAPTCHA with rotation and
font variation.
Font can be broadly divided into
serif and sans-serif fonts.
Some characters of serif font have
unique features for certain
characters that make recognition
easier.
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Proposedmethod - Captcha schemes
Scheme 9:
3D CAPTCHA with special
characters.
Use of special character
increases resistance.
Ex:[!, @, #, $, %, &, *, +, ?]
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Proposedmethod - Captcha schemes
Scheme 10:
3D CAPTCHA with
background texturecomposed of random
primitives .
Cleverly makes use of the
unique capabilities of human
visual systems.
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Results
Screenshot of evaluation website
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Results
The result of this survey was collected from 138people. The survey was comprised of 10 questions. Asurvey of usability, preference, hit ratio was used tomeasure the efficiency of 3D CAPTCHA.
From the result of the hit ratio, usability, and
preference, scheme 6 (3D CAPTCHA with rotationand character colour variation) is the best from ourten proposed schemes.
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Results - Usability
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Results - Preference
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Results Hit Ratio
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Conclusion
We propose a new generation of the CAPTCHA method that
uses 3D character instead of 2D character.
The advantage of using 3D characters in the CAPTCHA is, it
can be recognizable by human users and difficult to read by
bots.
Our new 3D CAPTCHA method uses a same input method
as that of several other websites using 2D.
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Conclusion
3D CAPTCHA is More secure.
Can increase the rate of its difficulty by applying other
effects such as increase the length of the CAPTCHA,
increase the rotation angle, or include more special
characters.
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Reference
Spamfizzle, http://spamfizzle.com/CAPTCHA.aspx.
CNET news, http://news.cnet.com/8301-17938_105-
10204300-1.html.
ABBYY FineReader 10, http://finereader.abbyy.com
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