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Captcha

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chinmaymadhav

The document discusses CAPTCHAs, which are programs that generate tests to tell humans and computers apart. It describes the origins of CAPTCHAs in preventing bots from adding URLs to search engines. The main types of CAPTCHAs are described as text, image, audio, video, puzzle, and 3D-based. reCAPTCHA is highlighted as a free captcha service that helps digitize books while determining if users are human. Some issues are that most text CAPTCHAs have been broken by advances in OCR and other techniques.

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Tough on bots Easy on humans Presentated By:- Chinmay Madhav B.I.T. - 3rd Year
• What is Captcha ? • Origin • Why do we need Captcha ? • Types of Captcha • ReCaptcha • Issuses With Captcha
Completely Automated Public Turing test to tell Computers and Humans Apart A CAPTCHA is aprogramthat can generate andgradetests that: • Most humanscan pass,but • Currentcomputer programscan't pass
TURING TEST • Human judge asks questions to two participants, one is a machine & the human. • The judge doesn’t know which is which. • After listening to the answer, ifthe judge fails to recognize which one is the machine, then the machine passes the test. REVERSE TURING TEST • CAPTCHAemploys a Reverse Turing Test • Judge = CAPTCHA program, participant = user • If the user passes CAPTCHA, he is human otherwise it is a machine.
• In 1997, it was first developed at AltaVista to prevent bots from adding URLs to their web search engine by Mark D. Lillibridge , Martin Abadi , Krishna Bharat and Andrei Broder . • In 2000,Yahoo coined the term CAPTCHA when they used it.
• Preventing Comment In Blog • Protecting Website Registration • Protecting Email Addresses • Online Polls
• Text Based Captcha • Image Based Captcha • Audio Based Captcha • Video Based Captcha • Puzzle Based Captcha • 3D Captcha
TEXT BASED CAPTCHA In this CAPTCHA we are Combining numbers , alphabets and also special character in which we use various various fonts. Using combination of all these we generate a CAPTCHA which is difficult for machine to identify IMAGE BASED CAPTCHA In these CAPTCHA ,user has to choose image based on the question ask by system captcha
VIDEO BASED CAPTCHA In these we provide video in which there are some hidden word or number is present . User has to enter this words. AUDIO BASED CAPTCHA In these we provide audio to user by which user has enter the text according to voice.
In these CAPTCHA puzzle is divided into chunks . User is suppose to combine this chunks so as to they fit into a given appropriate chunks of the puzzle. This one may be one of the more difficult ones to solve, but it is sure to keep out robotic predators. There are several types of three dimensional CAPTCHAs including both images and words. They call it the “SUPER- CAPTCHA.” PUZZLE BASED CAPTCHA 3D CAPTCHA
• Free captcha service that helps to digitize books, newspaper . • Two words are shown, one word is known as control word and another one is known as a questionable word. • System assumes that if human types the control word correctly, then the questionable word is also correct.
Captcha
• Most text based CAPTCHAs have been broken by software • OCR(Optical Character Recognization) • Segmentation • Other CAPTCHAs were broken by streaming the tests for unsuspecting users to solve.
Captcha

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Captcha

  • 1. Tough on bots Easy on humans Presentated By:- Chinmay Madhav B.I.T. - 3rd Year
  • 2. • What is Captcha ? • Origin • Why do we need Captcha ? • Types of Captcha • ReCaptcha • Issuses With Captcha
  • 3. Completely Automated Public Turing test to tell Computers and Humans Apart A CAPTCHA is aprogramthat can generate andgradetests that: • Most humanscan pass,but • Currentcomputer programscan't pass
  • 4. TURING TEST • Human judge asks questions to two participants, one is a machine & the human. • The judge doesn’t know which is which. • After listening to the answer, ifthe judge fails to recognize which one is the machine, then the machine passes the test. REVERSE TURING TEST • CAPTCHAemploys a Reverse Turing Test • Judge = CAPTCHA program, participant = user • If the user passes CAPTCHA, he is human otherwise it is a machine.
  • 5. • In 1997, it was first developed at AltaVista to prevent bots from adding URLs to their web search engine by Mark D. Lillibridge , Martin Abadi , Krishna Bharat and Andrei Broder . • In 2000,Yahoo coined the term CAPTCHA when they used it.
  • 6. • Preventing Comment In Blog • Protecting Website Registration • Protecting Email Addresses • Online Polls
  • 7. • Text Based Captcha • Image Based Captcha • Audio Based Captcha • Video Based Captcha • Puzzle Based Captcha • 3D Captcha
  • 8. TEXT BASED CAPTCHA In this CAPTCHA we are Combining numbers , alphabets and also special character in which we use various various fonts. Using combination of all these we generate a CAPTCHA which is difficult for machine to identify IMAGE BASED CAPTCHA In these CAPTCHA ,user has to choose image based on the question ask by system captcha
  • 9. VIDEO BASED CAPTCHA In these we provide video in which there are some hidden word or number is present . User has to enter this words. AUDIO BASED CAPTCHA In these we provide audio to user by which user has enter the text according to voice.
  • 10. In these CAPTCHA puzzle is divided into chunks . User is suppose to combine this chunks so as to they fit into a given appropriate chunks of the puzzle. This one may be one of the more difficult ones to solve, but it is sure to keep out robotic predators. There are several types of three dimensional CAPTCHAs including both images and words. They call it the “SUPER- CAPTCHA.” PUZZLE BASED CAPTCHA 3D CAPTCHA
  • 11. • Free captcha service that helps to digitize books, newspaper . • Two words are shown, one word is known as control word and another one is known as a questionable word. • System assumes that if human types the control word correctly, then the questionable word is also correct.
  • 13. • Most text based CAPTCHAs have been broken by software • OCR(Optical Character Recognization) • Segmentation • Other CAPTCHAs were broken by streaming the tests for unsuspecting users to solve.