CAPTCHA is a program that protects websites from bot attacks by generating tests that humans can pass but computers cannot. There are several types of CAPTCHAs including text, visual, graphics, and audio. reCAPTCHA is an updated version that also helps digitize books while blocking automated software from accessing websites. It remains one of the most reliable and easiest to use CAPTCHAs.

2. CAPTCHA
INVENTED BY
LUIS VON
AHN

3.  Definition
 Types Of Captcha
 Captcha Logic
 Do’s & Don’ts
 Applications
 3D Captcha
 Recaptcha
 Conclusion
OUTLINE:

4. CAPTCHA Means:Completely Automated Public Turing Test to
Tell Computers and Humans Apart.
It Is a Combination of Letters Which Human Can Understand
Computer Not.
It Is a Program That Protects Websites Against Bots by
Generating and Grading Tests That Humans Can Pass
Computer Can not.
Definition

5. IT LOOKS LIKE

6. -CAPTCHA is used to prevents hackers from using
automated software for spamming.
-CAPTCHA is used to check whether a human is
inputting the data or a automated computer script.
Why Do We Need Captcha ?

7. *Visual
-Text
-Gimpy
*Graphics
-Bongo
-Pix
*Audio
Types Of Captcha

8. TEXT
-These are Simple to Implement.
-Novel approach is to present the user with some
questions which only a human user can solve.
Example:
-What is the colour of the milk ?
Visual

9. Gimpy
-In Gimpy It Picks Up 10 Random Words From
Dictionary and Distorts Fills With Noise.
-User Has To Recognize Atleast 3 Words.
-If The User Is Correct, then He is Admitted.
Visual

10. BONGO
-It Displays a Series Of Blocks.
-Find The Common Characteristics In Given Set.
Graphics

11. PIX
-It Uses A Large Database Of Labeled Images.
-It Shows a Set Of Images, User has To Recognize the
Particular Image Among Those.
Graphics

12. -It Requires User To Solve A Speech Recognisation
Test.
-In This Version Of Captcha, Letters Are Read Aloud
Instead Of Being Displayed In An Image.
Audio

13. -Generate The Question.
-Present The Question To The User.
-If Correct, Allow User To Access.
-Persist The Correct Answer.
-Evaluate Answer If Incorrect, Start Again Generate
Different Captchas.
Captcha ‘Logic’

14. -Don’t Share Captcha Solution In Webpage's Meta Data.
-Avoid Repetition Of Questions.
-A Captcha Is Not Good If It Doesn’t Distort.
Do’s & Don’ts

15. -Web Registers.
-Smart Cards.
-Protecting Confidential Webpages.
-Online Polls.
-Prevent Dictionary Attacks.
-Preventing Spam In VOIP.
Applications

16. -It Is The Captcha “Nice To Humans,Bad To Machines”.
-It Is Also Called As “Super Captcha”.
-It Is Written In PHP.
3D Captcha

17. -It Is Updated Version Of Captcha.
-RECAPTCHA Acts Like a CAPTCHA and Also It Improves the
Process “Digitization Of Books”.
-By Adding reCAPTCHA To a Site, you Can Block Automated
Software.
-As Far As CAPTCHAs Go, reCAPTCHA Seems To Be Easiest To Use
and the Most Reliable.
RECAPTCHA

18. Images Of RECAPTCHA

19. “ As Internet is rapid the thing we need is Security,
by introducing CAPTCHAS we can achieve high
security for our Websites ”
Conclusion

20. ~THANK YOU!!
-Priyanka.G
-Madhuri.S
(Aditya Degree College for Women Rjy...)