 Introduction to CAPTCHA
 Good CAPTCHA properties
 CAPTCHA uses
 Types of CAPTCHA
 Advantages of existing CAPTCHA
 D...
 CAPTCHA -Completely Automated Public
Turing test to tell Computers and
Humans Apart.
 CAPTCHA program generates the cha...
 Security:The security dimension determines
its strength for preventing the variant attacks.
 Usability: usability dimen...
CATCHA has been used extensively in online
applications:
 Online Ticket Reservation,
 Online Polls,
 Online Banking,
 ...
 Text based CAPTCHA
 Image based CAPTCHA
 It makes impossible for computers to pass
the CAPTCHA challenges.
 It prevent Botnet attacks.
 It prevents the spam at...
Existing CAPTCHA is vulnerable to :
 The third Party Human Attack
 Binarization
 Vertical Segmentation
 Phishing, Sess...
 Its personalized image base CAPTCHA.
 It identifies Legitimate and Illegitimate users.
 It generates lot of personaliz...
 Idea :To use a geographic scene image.
 Image is privately known to each user.
 Working : Generates a set of candidate...
 The challenges are vertically and horizontally
rotated images of the registered private
image.
Fig(1)The random challeng...
 Condition :Security threshold condition
if | GH(x)- GH(y) <= T | then pass HIP test.
 GH(x)- denotes the function to ca...
1. U User’s log-in account;
2. PW User’s log-in password;
3. A Pick a personalized Geo-location
image which only known to ...
 U User’s log-in account;
 while U is true do
 Qu
x and Qu
y M(U);
 end while
 R G(Qu
x; Qu
y );
 C Randomize(R);
Challenge
Quantity
Challenge can
be recorded
Broken by OCR
Typical
CAPTCHA
Plenty &
Dynamic
No Text-based: Yes
Image-based...
Automatic
Attack
Genuine User
(Human)
3rd Party
Human
Typical
CAPTCHA
Fail Pass Pass
Personalized
Challenge
Pass Pass Fail...
Geo captcha - a novel personalized captcha using geographic
Geo captcha - a novel personalized captcha using geographic
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Geo captcha - a novel personalized captcha using geographic

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Geo captcha - a novel personalized captcha using geographic

  1. 1.  Introduction to CAPTCHA  Good CAPTCHA properties  CAPTCHA uses  Types of CAPTCHA  Advantages of existing CAPTCHA  Disadvantages of existing CAPTCHA  Geo-CAPTCHA  Geo-CAPTCHA Passing HIP test Condition
  2. 2.  CAPTCHA -Completely Automated Public Turing test to tell Computers and Humans Apart.  CAPTCHA program generates the challenges.  It recognize the humans’ behaviours.  It tells humans and computers apart.
  3. 3.  Security:The security dimension determines its strength for preventing the variant attacks.  Usability: usability dimension determines the necessity of ”user friendly” when CAPTCHA is deployed
  4. 4. CATCHA has been used extensively in online applications:  Online Ticket Reservation,  Online Polls,  Online Banking,  Web-based E-mail Service
  5. 5.  Text based CAPTCHA  Image based CAPTCHA
  6. 6.  It makes impossible for computers to pass the CAPTCHA challenges.  It prevent Botnet attacks.  It prevents the spam attacks.
  7. 7. Existing CAPTCHA is vulnerable to :  The third Party Human Attack  Binarization  Vertical Segmentation  Phishing, Session Hijacking, Relay Attacks and Man in the Middle Attacks  Key-logger and Hidden Camera
  8. 8.  Its personalized image base CAPTCHA.  It identifies Legitimate and Illegitimate users.  It generates lot of personalized challenges which makes it suitable for cloud computing applications.  It non-recordable & OCR can’t defeat it.  Its specifically designed to deal with third party attacks.  It also prevents Automatic programming attacks.
  9. 9.  Idea :To use a geographic scene image.  Image is privately known to each user.  Working : Generates a set of candidate images for a location selected by each user.  User selects a geo-location image from the set .  This is registered private image to be used as the correct answer to the challenges.
  10. 10.  The challenges are vertically and horizontally rotated images of the registered private image. Fig(1)The random challenge of any angle Fig(2)The rotated solution of correct angle street view
  11. 11.  Condition :Security threshold condition if | GH(x)- GH(y) <= T | then pass HIP test.  GH(x)- denotes the function to calculate the hash value of image x.  GH(y)- denotes the function to calculate the hash value of image y.  T- we define a error threshold .
  12. 12. 1. U User’s log-in account; 2. PW User’s log-in password; 3. A Pick a personalized Geo-location image which only known to the user; 4. Qu x and Qu y C(A); 5. R G(Qu x;Qu y); 6. S Pick a solution image from R; 7. Save the h, p , (Qu x; Qu y ), U and PW to database;
  13. 13.  U User’s log-in account;  while U is true do  Qu x and Qu y M(U);  end while  R G(Qu x; Qu y );  C Randomize(R);
  14. 14. Challenge Quantity Challenge can be recorded Broken by OCR Typical CAPTCHA Plenty & Dynamic No Text-based: Yes Image-based: No Personalized challenge Fixed & Static Yes Yes Geo-CAPTCHA Fixed & Dynamic No No
  15. 15. Automatic Attack Genuine User (Human) 3rd Party Human Typical CAPTCHA Fail Pass Pass Personalized Challenge Pass Pass Fail Geo-CAPTCHA Fail Pass Fail

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