Geo-CAPTCHA - A Novel Personalized CAPTCHA Using

Geographic Concept to Defend Against Third Party Human Attack

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

CONTENTS

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.

Introduction to CAPTCHA

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

Good CAPTCHA properties

CATCHA has been used extensively in online applications:

Online Ticket Reservation, Online Polls, Online Banking, Web-based E-mail Service

CAPTCHA uses

Text based CAPTCHA

Image based CAPTCHA

Types of CAPTCHA

It makes impossible for computers to pass the CAPTCHA challenges.

It prevent Botnet attacks.

It prevents the spam attacks.

Advantages of existing CAPTCHA

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

Disadvantages of existing CAPTCHA

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.

Geo-CAPTCHA

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.

Geo-CAPTCHA Idea & Working

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

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 .

Geo-CAPTCHA Passing HIP test Condition

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 Quy C(A);

5. R G(Qux;Qu

y);

6. S Pick a solution image from R;7. Save the h, p , (Qu

x; Quy ), U and PW to

database;

GeoCAPTCHA Registration

U User’s log-in account; while U is true do Qu

x and Quy M(U);

end while R G(Qu

x; Quy );

C Randomize(R);

Geo-CAPTCHA Login

Challenge Quantity

Challenge can be recorded

Broken by OCR

Typical CAPTCHA

Plenty & Dynamic

No Text-based: YesImage-based: No

Personalized challenge

Fixed & Static Yes Yes

Geo-CAPTCHA Fixed & Dynamic

No No

THE COMPARISONS BETWEEN TYPICAL CAPTCHA, PERSONALIZEDCAPTCHA ANDGEOCAPTCHA

AutomaticAttack

Genuine User(Human)

3rd PartyHuman

Typical CAPTCHA

Fail Pass Pass

Personalized Challenge

Pass Pass Fail

Geo-CAPTCHA Fail Pass Fail

THE GOAL OF THREE CAPTCHA

THANK YOU