Introduction to CAPTCHA and how to use in java web applications

1. Slide 1
Let’s Have Quiz

2. Slide 2
What Computers
Cannot Do
Which Humans
Can Do?

3. Slide 3
Can’t
Sing
Can’t
Calculate Can’t
Teach
A
B
C

4. Slide 4
Can’t
Read
Distorted Text
Secret Answer D

5. Slide 5
This
INABILITY
of Computers
was seen as an
OPPORTUNITY
to solve
Big Problems

6. Slide 6
Big Problems
In
Practical Security
Of
Web Applications

7. Slide 7
Comment Spam in Blogs.
Free Registration Sites Attacks.
Email Addresses From Scrapers.
Dictionary Attacks.
 Search Engine Bots.
 Worms and Spam.
 Online Polls.
Source: http://www.captcha.net/

8. Slide 8
How to Solve This?
by
GENERATING and GRADING
TESTS
that HUMANS can PASS
but
CURRENT COMPUTER PROGRAMS
CANNOT.

9. Slide 9
Can’t
Read
Distorted Text
Secret Answer D

10. Slide 10
CA PTC HA
Completely
Automated
Public
Turing test to tell
Computers and
Humans
Apart

11. 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/

12. Slide 12
Demo
Source: http://www.captcha.net/

13. Slide 13
Demo
Source: http://www.captcha.net/

14. Slide 14
How CAPTCHA
Can Solve
Above Problems?

15. Slide 15
 Preventing Comment Spam in
Blogs.
Only humans can enter comments
on a blog
 Protecting Website Registration.
To ensure that only humans
obtain free accounts.
Source: http://www.captcha.net/

16. Slide 16
Protecting Email Addresses
From Scrapers.
To require users to solve a
CAPTCHA before showing your
email address.
 Worms and Spam.
"I will only accept an email if I know
there is a human behind the other
computer."
Source: http://www.captcha.net/

17. Slide 17
 Preventing Dictionary Attacks.
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.
Source: http://www.captcha.net/

18. Slide 18
 Search Engine Bots.
In order to truly guarantee that
bots won't enter a web site
 Online Polls.
The poll ensures that only
humans can vote.
Source: http://www.captcha.net/

19. Slide 19
Want To Try Yourself?

20. Slide 20
You Need
1) JAR
2) Mappings in web.xml
3) JSP with HTML form
4) Validation code in ACTION
Source: http://simplecaptcha.sourceforge.net/installing.html

21. Slide 21
Resources
http://www.captcha.net/
http://simplecaptcha.sourceforge.net/

22. Slide 22
Questions

23. Slide 23
Food For Thoughts
CAPTCHA
and
Artificial Intelligence
Re CAPTCHA