CAPTCHA Presented By : Ashish Madhok MCA-2 SEM 13097019
Topics To be Covered  : 1).  What is a CAPTCHA ? 2). Why it is useful? 3). About CAPTCHA   4). Origin 5). Applications 6)....
8).  Circumvention 9).  Help against spam 10).  Need of a CAPTCHA 11).  CAPTCHA-Pros and Cons 12). Guidelines
WHAT IS A CAPTCHA ? <ul><li>C ompletely  A utomated  P ublic  T uring test to tell  C omputers and  H umans  A part   </li...
<ul><li>Simple Verification made up of:- </li></ul><ul><li>The CAPTCHA image and the CAPTCHA code that generates it. </li>...
WHY IS IT USEFUL ? <ul><li>Designed to prevent BOTS from abusing internet services…BOTS </li></ul><ul><li>Defend e-commerc...
ABOUT CAPTCHA  !   <ul><li>Pessimal Print </li></ul><ul><li>Create a  distorted background. </li></ul><ul><li>High levels ...
ORIGIN <ul><li>Controlled access to web services in a 1996 manuscript of Moni Naor. </li></ul><ul><li>A simple CAPTCHA-dev...
APPLICATIONS <ul><li>1).  Preventing Comment Spam in  Blogs. </li></ul><ul><li>2).  Protecting Website Registration. </li>...
CHARACTERISTICS <ul><li>Current computers are unable to accurately solve. </li></ul><ul><li>Most humans can solve. </li></...
CIRCUMVENTION <ul><li>Few approaches to defeat CAPTCHA :- </li></ul><ul><li>HUMAN SOLVERS   </li></ul><ul><li>INSECURE IMP...
HOW CAN CAPTCHA HELP AGAINST SPAM? <ul><li>Great help in downsizing or diminishing  FORM   SPAMMING </li></ul><ul><li>Bots...
IMAGE-RECOGNITION CAPTCHAs <ul><li>Alternative for text based CAPTCHAs </li></ul><ul><li>POTENTIAL PROBLEMS  :- </li></ul>...
PROS AND CONS <ul><li>PROS </li></ul><ul><li>Help to fight automatic bots from spamming web site forms. </li></ul><ul><li>...
GUIDELINES <ul><li>Accessibility </li></ul><ul><li>Image Security </li></ul><ul><li>Script Security </li></ul>
THANK  YOU !!!
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Captcha1

  1. 1. CAPTCHA Presented By : Ashish Madhok MCA-2 SEM 13097019
  2. 2. Topics To be Covered : 1). What is a CAPTCHA ? 2). Why it is useful? 3). About CAPTCHA 4). Origin 5). Applications 6). Characteristics 7). Accessibility
  3. 3. 8). Circumvention 9). Help against spam 10). Need of a CAPTCHA 11). CAPTCHA-Pros and Cons 12). Guidelines
  4. 4. WHAT IS A CAPTCHA ? <ul><li>C ompletely A utomated P ublic T uring test to tell C omputers and H umans A part </li></ul><ul><li>An automated test that can distinguish between machines and humans online. </li></ul><ul><li>A type of challenge-response test. </li></ul><ul><li>Involves one computer (a server). </li></ul>
  5. 5. <ul><li>Simple Verification made up of:- </li></ul><ul><li>The CAPTCHA image and the CAPTCHA code that generates it. </li></ul><ul><li>A form field into which the code one sees in the CAPTCHA image must be inserted – and an enter button. </li></ul><ul><li>A separate code which checks that the code inserted manually into the field was correct. </li></ul>
  6. 6. WHY IS IT USEFUL ? <ul><li>Designed to prevent BOTS from abusing internet services…BOTS </li></ul><ul><li>Defend e-commerce systems from bots. Eg-Yahoo. </li></ul><ul><li>Requirement of a common type of CAPTCHA. </li></ul><ul><li>Described as Reverse Turing Test. </li></ul>
  7. 7. ABOUT CAPTCHA ! <ul><li>Pessimal Print </li></ul><ul><li>Create a distorted background. </li></ul><ul><li>High levels of warping on the text. </li></ul><ul><li>Baffle Text </li></ul><ul><li>Focuses on making segmentation difficult by adding an angled line. </li></ul>
  8. 8. ORIGIN <ul><li>Controlled access to web services in a 1996 manuscript of Moni Naor. </li></ul><ul><li>A simple CAPTCHA-developed in 1995 by Anton Lam. </li></ul><ul><li>Other primitive CAPTCHA-developed in 1997 at Alta Vista by Andrei Broder. </li></ul><ul><li>Developed in 2000 by Vin Ahn and Blum </li></ul>
  9. 9. APPLICATIONS <ul><li>1). Preventing Comment Spam in Blogs. </li></ul><ul><li>2). Protecting Website Registration. </li></ul><ul><li>3). Online Polls. </li></ul><ul><li>4). Preventing Dictionary Attacks. </li></ul><ul><li>5). Search Engine Bots. </li></ul><ul><li>6). Worms and Spam. </li></ul>
  10. 10. CHARACTERISTICS <ul><li>Current computers are unable to accurately solve. </li></ul><ul><li>Most humans can solve. </li></ul><ul><li>Does not rely on attacker never having seen the CAPTCHA before. </li></ul><ul><li>Is able to automatically generate new challenges that require artificial intelligence techniques to solve. </li></ul>
  11. 11. CIRCUMVENTION <ul><li>Few approaches to defeat CAPTCHA :- </li></ul><ul><li>HUMAN SOLVERS </li></ul><ul><li>INSECURE IMPLEMANTATION </li></ul><ul><li>COMPUTER CHARACTER RECOGNITION </li></ul>
  12. 12. HOW CAN CAPTCHA HELP AGAINST SPAM? <ul><li>Great help in downsizing or diminishing FORM SPAMMING </li></ul><ul><li>Bots go around the web </li></ul><ul><li>Find forms </li></ul><ul><li>Send thousands of e-mails through that </li></ul><ul><li>Fill in the form – sign up for 100 free email accounts, services or products. </li></ul>
  13. 13. IMAGE-RECOGNITION CAPTCHAs <ul><li>Alternative for text based CAPTCHAs </li></ul><ul><li>POTENTIAL PROBLEMS :- </li></ul><ul><li>Difficult for a small site to acquire a large dictionary of images. </li></ul><ul><li>Ask the user to make a binary choice. </li></ul>
  14. 14. PROS AND CONS <ul><li>PROS </li></ul><ul><li>Help to fight automatic bots from spamming web site forms. </li></ul><ul><li>CONS </li></ul><ul><li>Not a 100 % spammer proof system </li></ul><ul><li>Not safe for bank account details or credit card pins </li></ul><ul><li>Sometimes humans can’t recognize it. </li></ul>
  15. 15. GUIDELINES <ul><li>Accessibility </li></ul><ul><li>Image Security </li></ul><ul><li>Script Security </li></ul>
  16. 16. THANK YOU !!!
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