Slide 1

Let’s Have Quiz

Slide 2

What Computers Cannot Do

Which Humans Can Do?

Slide 3

Can’t Sing

A

Can’t Calculate

B

Can’t Teach

C

Slide 4

Can’t Read

Distorted Text

Secret Answer

D

Slide 5

This INABILITY

of Computerswas seen as

an OPPORTUNITY to solve

Big Problems

Slide 6

Web Applications

Big ProblemsIn

Practical Security

Of

Slide 7

Comment Spam in Blogs.

Dictionary Attacks.

Search Engine Bots.

Worms and Spam.

Free Registration Sites Attacks.

Email Addresses From Scrapers.

Online Polls.Source: http://www.captcha.net/

Slide 8

How to Solve This? by

GENERATING and GRADINGTESTS

that HUMANS can PASS but

CURRENT COMPUTER PROGRAMS CANNOT.

Slide 9

Can’t Read

Distorted Text

Secret Answer

D

Slide 10

CCompletely Automated Public

Turing test to tellComputers andHumansApart

A PT C HA

Slide 11

The term CAPTCHA was coined in 2000

by Luis von Ahn, Manuel Blum, Nicholas Hopper and

John Langford of Carnegie Mellon

University.Source: http://www.captcha.net/

Slide 12

Demo

Source: http://www.captcha.net/

Slide 13

Demo

Source: http://www.captcha.net/

Slide 14

How CAPTCHA Can Solve

Above Problems?

Slide 15

Preventing Comment Spam in Blogs.

Protecting Website Registration.

Only humans can enter comments on a blog

To ensure that only humans obtain free accounts.

Source: http://www.captcha.net/

Slide 16

Worms and Spam.

Protecting Email Addresses From Scrapers.

To require users to solve a CAPTCHA before showing your

email address.

"I will only accept an email if I know there is a human behind

the other computer."Source: http://www.captcha.net/

Slide 17

Prevent a computer from being able to iterate through the entire space of passwords

by requiring it to solve a CAPTCHA after a certain

number of unsuccessful logins.

Preventing Dictionary Attacks.

Source: http://www.captcha.net/

Slide 18

Search Engine Bots.

Online Polls.

In order to truly guarantee that bots won't enter a web

site

The poll ensures that only humans can vote.

Source: http://www.captcha.net/

Slide 19

Want To Try Yourself?

Slide 20

You Need

2) Mappings in web.xml

3) JSP with HTML form

4) Validation code in ACTION

1) JAR

Source: http://simplecaptcha.sourceforge.net/installing.html

Slide 21

Resources

http://www.captcha.net/

http://simplecaptcha.sourceforge.net/

Slide 22

Questions

Slide 23

Food For Thoughts

CAPTCHA and

Artificial Intelligence

Re CAPTCHA