A SEMINAR ON   CAPTCHA                    By-                    ABHIMANYU SOOD                     0902810002 (C.S.E.)   ...
CAPTCHA: Outline       Meaning of CAPTCHA       Origin of CAPTCHA       Different types of CAPTCHA       Application o...
CAPTCHA: Acronym      Completely      Automated      Public      Turing Test to Tell      Computers and      Humans ...
CAPTCHA: Meaning      Completely - Whole      Automated - Made by machine      Public - Universally known      Turing ...
CAPTCHA: Example
CAPTCHA: Origin       1997: Andrei Broder at AltaVista wanted to        prevent bots from automatically submitting       ...
CAPTCHA: Deciding Human or                Bot?       A puzzle or problem that is easy for        humans to solve and very...
CAPTCHA: Basic types    Printed CAPTCHA    Handwritten CAPTCHA
PRINTED CAPTCHA    Printed CAPTCHA is difficult to break    Lots of algorithms are available to     generate these    C...
PRINTED CAPTCHA: Baffle       Developed by Monica Chew and Henry Baird       Uses pronounceable English characters(with ...
PRINTED CAPTCHA: Pessimal       Developed by Allison Coates and Henry Baird        and Richard Fateman       Uses the de...
HANDWRITTEN CAPTCHA      Less frequently used because computers can       easily identify the handwriting rather than tex...
HANDWRITTEN CAPTCHA: Example
CAPTCHA: Advanced Types       Text based           Ez-gimpy           R-gimpy (Google)           Simard’s HIP (MSN)   ...
CAPTCHA: Advanced Types     Audio   based     Face   Recognition     Logic   Puzzles     KittenAuth
CAPTCHA: Text Based       Gimpy, ez-gimpy           Pick a word or words from a dictionary           Distort them and, ...
CAPTCHA: Text Based(Gimpy)                      EZ-GYMPY                       R-GIMPY
CAPTCHA: Text Based       Simard’s HIP         Pick   random letters and numbers         Distort   them and add arcs
CAPTCHA: Graphics Based         (Bongo)       A visual recognition problem       Two sets of shapes with a distinguishin...
CAPTCHA: Graphics Based (Pix)       A database of labeled images of recognizable objects       Randomly chooses an objec...
CAPTCHA: Audio      Pick a word or a sequence of numbers at       random      Render them into an audio clip using a Tex...
CAPTCHA: Face Recognition
CAPTCHA: Logic Puzzles       Easy trivia questions       Example: Which of the following is a bird?                   El...
CAPTCHA: KittenAuth       “The Cutest Human Test”       A 3x3 matrix of cute animals       Choose the 3 kittens       ...
CAPTCHA:- Application       Online polls       Free e-mail services       Search engines       Prevention to Worms and...
CAPTCHA:- Application (E-Mail)     Hotmail Registration     Yahoo! Registration
CAPTCHA: Properties       CAPTCHA should be automatically generated and        graded for good performance       Test ca...
CAPTCHA: Circumvention         (Breaking)       Introducing bugs in the system, so that it        allows the attacker to ...
CAPTCHA: Circumvention         (Breaking)       Pre-Processing: Removal of background clutter        and noise.       Cl...
CAPTCHA: Conclusion       They are crucial to preventing bot attacks       Hopefully, they will become more user-friendl...
CAPTCHA: Reference     WIKIPEDIA     GOOGLE     http://captchas.net     Numerous sites that provide various      stude...
CAPTCHA:
CAPTCHA:      Any     Queries.        ?
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Captcha ppt

  1. 1. A SEMINAR ON CAPTCHA By- ABHIMANYU SOOD 0902810002 (C.S.E.) DEPARTMENT OF COMPUTER SCEINCE AND ENGINEERING IDEAL INSTITUTE OF TECHNOLOGY, GHAZIABAD [U.P.] (Approved by AICTE and affiliated to GBTU, Lucknow U.P.) 2011-2012
  2. 2. CAPTCHA: Outline  Meaning of CAPTCHA  Origin of CAPTCHA  Different types of CAPTCHA  Application of CAPTCHA  Properties of CAPTCHA  Circumvention/Breaking of CAPTCHA  Reference  Conclusion
  3. 3. CAPTCHA: Acronym  Completely  Automated  Public  Turing Test to Tell  Computers and  Humans  Apart
  4. 4. CAPTCHA: Meaning  Completely - Whole  Automated - Made by machine  Public - Universally known  Turing Test to Tell - Test presented by Alan Turing  Computers and  Humans  Apart
  5. 5. CAPTCHA: Example
  6. 6. CAPTCHA: Origin  1997: Andrei Broder at AltaVista wanted to prevent bots from automatically submitting sites for indexing  He decided to add a test to the submission page  He performed a reverse scan through Optical Character Recognition(OCR) scanner  2000: Luis von Ahn, Manuel Blum & John Langford at CMU coined term CAPTCHA
  7. 7. CAPTCHA: Deciding Human or Bot?  A puzzle or problem that is easy for humans to solve and very difficult for computers is given  If the puzzle is solved correctly, you are considered human and can continue  Also known as reverse Turing Test- Human Interaction Proof.
  8. 8. CAPTCHA: Basic types Printed CAPTCHA Handwritten CAPTCHA
  9. 9. PRINTED CAPTCHA  Printed CAPTCHA is difficult to break  Lots of algorithms are available to generate these  Computers cannot identify these easily  Two major types are there viz. Baffle text, Pessimal print.
  10. 10. PRINTED CAPTCHA: Baffle  Developed by Monica Chew and Henry Baird  Uses pronounceable English characters(with various masking techniques)that are not present in English dictionary
  11. 11. PRINTED CAPTCHA: Pessimal  Developed by Allison Coates and Henry Baird and Richard Fateman  Uses the degradation model simulating physical defects caused by printing and scanning of printed text
  12. 12. HANDWRITTEN CAPTCHA  Less frequently used because computers can easily identify the handwriting rather than text images (OCR Scanners)  Use of transformations by adding lines, arcs, circles etc.
  13. 13. HANDWRITTEN CAPTCHA: Example
  14. 14. CAPTCHA: Advanced Types  Text based  Ez-gimpy  R-gimpy (Google)  Simard’s HIP (MSN)  Graphic based  Bongo  Pix
  15. 15. CAPTCHA: Advanced Types  Audio based  Face Recognition  Logic Puzzles  KittenAuth
  16. 16. CAPTCHA: Text Based  Gimpy, ez-gimpy  Pick a word or words from a dictionary  Distort them and, add noise and background  Gimpy-r, Google’s CAPTCHA  Pick random letters  Distort them and, add noise and background
  17. 17. CAPTCHA: Text Based(Gimpy) EZ-GYMPY R-GIMPY
  18. 18. CAPTCHA: Text Based  Simard’s HIP  Pick random letters and numbers  Distort them and add arcs
  19. 19. CAPTCHA: Graphics Based (Bongo)  A visual recognition problem  Two sets of shapes with a distinguishing characteristic  Must choose which set the shape belongs to
  20. 20. CAPTCHA: Graphics Based (Pix)  A database of labeled images of recognizable objects  Randomly chooses an object and displays N pictures of it  Must correctly identify the object  Pictures can or cannot be distorted
  21. 21. CAPTCHA: Audio  Pick a word or a sequence of numbers at random  Render them into an audio clip using a Text To Speech (TTS) software  Distort the audio clip  Ask the user to identify and type the word or numbers
  22. 22. CAPTCHA: Face Recognition
  23. 23. CAPTCHA: Logic Puzzles  Easy trivia questions  Example: Which of the following is a bird? Elephant, Tiger, Robin  Simple mathematical expressions: What is the solution? (2+2)  It’s very accommodating to create a big enough database of these simple logic based puzzles
  24. 24. CAPTCHA: KittenAuth  “The Cutest Human Test”  A 3x3 matrix of cute animals  Choose the 3 kittens  Strategy is to use animals that look similar to kittens
  25. 25. CAPTCHA:- Application  Online polls  Free e-mail services  Search engines  Prevention to Worms and spams  Preventing dictionary attack  Newsgroups, Blogs, etc…
  26. 26. CAPTCHA:- Application (E-Mail) Hotmail Registration Yahoo! Registration
  27. 27. CAPTCHA: Properties  CAPTCHA should be automatically generated and graded for good performance  Test can be taken quickly and easily by human users  Test will accept virtually all human users and reject software agents  Test has been able to resist attacks for many years, despite the technological advances and knowledge of algorithms, but are they full-proof ??
  28. 28. CAPTCHA: Circumvention (Breaking)  Introducing bugs in the system, so that it allows the attacker to completely bypass the CAPTCHA.  Improving character recognition software.  Using cheap Human labour to process the tests(impractical in real world), & as done by Humans so the purpose of CAPTCHA still holds.
  29. 29. CAPTCHA: Circumvention (Breaking)  Pre-Processing: Removal of background clutter and noise.  Classification: Identifying the character in each region.  Segmentation: Splitting the image into regions which each contain a single character.
  30. 30. CAPTCHA: Conclusion  They are crucial to preventing bot attacks  Hopefully, they will become more user-friendly to people with disabilities (visual/mental)  CAPTCHA’s are mainly produced from Asynchronous Java-script And XML (AJAX) & using a bit of Hypertext Preprocessor (PHP) technology  Various algorithms are present
  31. 31. CAPTCHA: Reference  WIKIPEDIA  GOOGLE  http://captchas.net  Numerous sites that provide various students like us to gather, discuss & help each other– http://www.scribd.com/ http://www.slideshare.net/
  32. 32. CAPTCHA:
  33. 33. CAPTCHA: Any Queries. ?
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