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CAPTCHA : ARE U A HUMAN SORRY I HAD TO ASK

CAPTCHA : ARE U A HUMAN SORRY I HAD TO ASK. Pranaya Priyankar Mishra B.Tech (CSE) Roll:06165 GITA. AGENDA. What is CAPTCHA? Types of CAPTCHA Where to use CAPTCHAs? Guidelines when making a CAPTCHA Ways to break CAPTCHAs reCAPTCHA Human Computation Games. AGENDA.

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CAPTCHA : ARE U A HUMAN SORRY I HAD TO ASK

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  1. CAPTCHA: ARE U A HUMANSORRY I HAD TO ASK PranayaPriyankarMishra B.Tech(CSE) Roll:06165 GITA

  2. AGENDA • What is CAPTCHA? • Types of CAPTCHA • Where to use CAPTCHAs? • Guidelines when making a CAPTCHA • Ways to break CAPTCHAs • reCAPTCHA • Human Computation Games

  3. AGENDA • What is CAPTCHA? • Types of CAPTCHA • Where to use CAPTCHAs? • Guidelines when making a CAPTCHA • Ways to break CAPTCHAs • reCAPTCHA • Human Computation Games

  4. CAPTCHA Completely Automated Public Turing test to tell Computers and Humans Apart

  5. BEGININGS. . . . . Created in 2000 for Yahoo to prevent automated e-mail account registration, by Luis von Ahn, Manuel Blum, Nicholas Hopper and John Langford in Carnegie Mellon University.

  6. LUIS VON AHN (1978 - )

  7. What is CAPTCHA? A program that can tell whether its user is a human or a computer. It uses a type of challenge-response test to determine that the response is not generated by a computer.

  8. TURING TEST „Standard Interpretation" player C, the interrogator, is tasked with trying to determine which player - A or B - is a computer and which is a human.

  9. REVERSE TURING TEST A CAPTCHA is sometimes described as a reverse Turing test, because it is administered by a machine and targeted to a human.

  10. So, CAPTCHA is… A programthat can generate and grade tests that: • Most humanscan pass; • Current computer programs cannot pass.

  11. AGENDA • What is CAPTCHA? • Types of CAPTCHA • Where to use CAPTCHAs? • Guidelines when making a CAPTCHA • Ways to break CAPTCHAs • reCAPTCHA • Human Computation Games

  12. TYPE:EARLY CAPTCHA • Generated by the EZ-Gimpy and Gimpy program • Used previously on Yahoo!

  13. Type: Improved CAPTCHA • high contrast for human readability; • medium, per-character perturbation; • random fonts per character; • low background noise;

  14. Type: A modern CAPTCHA • rather than attempting to create a distorted background and high levels of warping on the text; • focus on making segmentation difficult by adding an angled line;

  15. Type: A modern CAPTCHA • another way to make segmentation difficult is to crowd symbols together; • this can be read by humans but cannot be segmented by bots;

  16. Other Types of CAPTCHA • Animated CAPTCHAs • 3D CAPTCHA • ASCII art • Reverse CAPTCHA "Leave this field blank"

  17. OTHER……… • Distinguish pictures of dogs from cats • Visual Puzzle(BONGO) • Choose a word that relates to all the images(PIX) • Trivia questions • Math and word problems • 3D Object CAPTCHA • Solve failed OCR inputs(reCAPTCHA) • Audio CAPTCHA • Video CAPTCHA

  18. Other: Distinguish pictures • Microsoft Asirra (Animal Species Image Recognition for Restricting Access); • KittenAuth Project .

  19. Other: Mathematical CAPTCHA

  20. Other: 3D Object CAPTCHA You must enter them in the exact sequence listed: • The Head of the Walking Man, • The Vase, • The Back of the Chair.

  21. AGENDA • What is CAPTCHA? • Types of CAPTCHA • Where to use captchas? • Guidelines when making a CAPTCHA • Ways to break CAPTCHAs • reCAPTCHA • Human Computation Games

  22. WHERE TO USE CAPTCHAs • Worms and Spam • Preventing Comment Spam in Blogs • Protecting Email Addresses From Scrapers • Online Polls • Protecting Website Registration • Preventing Dictionary Attacks • Search Engine Bots • Book Digitization

  23. AGENDA • What is CAPTCHA? • Types of CAPTCHA • Where to use CAPTCHAs? • Guidelines when making a CAPTCHA • Ways to break CAPTCHAs • reCAPTCHA • Human Computation Games

  24. GUIDELINES…… • Image Security • Script Level Security. • Security Even After Wide-Spread Adoption • Accessibility.(Implement Audio Captcha)

  25. GUIDELINES: ACCESIBILITY Worst CAPTCHAs:

  26. AGENDA • What is CAPTCHA? • Types of CAPTCHA • Where to use CAPTCHAs? • Guidelines when making a CAPTCHA • Ways to break CAPTCHAs • reCAPTCHA • Human Computation Games

  27. Ways to break CAPTCHAs • Exploiting bugs in the implementation that allow the attacker to completely bypass the CAPTCHA; • Improving Character Recognition software (OCR – Optical Character Recognition ); • Using cheap human labor to process the tests (sweatshops).

  28. Break: Character Recognition • Programs that have the following functions: • Extraction of the image from the web page • Removal of background clutter, for example with color filters and detection of thin lines; • Segmentation, i.e. splitting the image into regions each containing a single letter; • Identifying the letter for each region.

  29. Attacks – EZ-Gimpy 2000 • Yahoo's early CAPTCHA called "EZ-Gimpy“; • The program picks a word from a dictionary, and produces a distorted and noisy image of the word; • Algorithm for breaking EZ-Gimpy (92%): • Locate possible letters at various locations; • Construct graphof consistent letters; • Look for plausible words in the graph.

  30. Attacks – EZ-Gimpy 2000 EZ-Gimpy Possible Letters Graph of Letters Plausible Words

  31. Attacks – SimpleOCR Engine 2002

  32. AGENDA • What is CAPTCHA? • Types of CAPTCHA • Where to use CAPTCHAs? • Guidelines when making a CAPTCHA • Ways to break CAPTCHAs • reCAPTCHA • Human Computation Games

  33. reCAPTCHA(2007) • New form of CAPTCHA that also helps digitize books; • The words displayed to the user come directly from old books that are being digitized; • Words that OCR could not identify;

  34. reCAPTCHA • Pairs an unknown word with a known one; • Distorts them both and puts a line through them and then sent them to be proofread; • Respondent answers both elements: • half of effort validates the challenge; • the other half is captured as work.

  35. reCAPTCHA

  36. AGENDA • What is CAPTCHA? • Types of CAPTCHA • Where to use CAPTCHAs? • Guidelines when making a CAPTCHA • Ways to break CAPTCHAs • reCAPTCHA • Human Computation Games

  37. HUMAN COMPUTATION GAMES • ESP Game • Tag A Tune Game • Matchin Game • Squigl Game • Verbosity Game

  38. Player 1 Player 2 Guessing: CAR Guessing : HAT Guessing: KID Success! You agree on CAR Guessing : BOY Guessing : CAR Success! You agree on CAR ESP GAME

  39. TAG A TUNE GAME

  40. MATCHIN GAME

  41. SQUIGL GAME

  42. VERBOSITY GAME

  43. REFERANCES • www.captcha.net • www.recaptcha.net • www.howstuffworks.com • www.youtube.com

  44. PREDICTIONS…… The CAPTCHA spam arms race will lead to the creation of ARTIFICIAL INTELLIGENCE……

  45. THANK YOU

  46. THANK YOU

  47. QUERIES ?

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