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CAPTCHA - PowerPoint PPT Presentation


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CAPTCHA. Presentation by Annette Tsui, Section 2. What is CAPTCHA?. CAPTCHA: Completely Automated Public Turing test to tell Computers and Humans Apart Introduced by Alan Turing in 1950 - “If a computer’s performance was indistinguishable from a human, it could be deemed intelligent.”

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captcha

CAPTCHA

Presentation by

Annette Tsui, Section 2

what is captcha
What is CAPTCHA?
  • CAPTCHA: Completely Automated Public Turing test to tell Computers and Humans Apart
  • Introduced by Alan Turing in 1950 - “If a computer’s performance was indistinguishable from a human, it could be deemed intelligent.”
  • Still not able to do completely, but programs have been developed that are able to pass tests that humans can pass
types of captchas
Types of CAPTCHAs
  • Visual-based and Sound-based
  • Visual-based examples:
    • Gimpy, EZ-Gimpy, Gimpy-r, Pessimal Print, Baffletext
    • Sound based: Sounds CAPTCHA used in Hotmail®, Yahoo! ®, and Altavista® new login accounts
visual based captchas
Visual-based CAPTCHAs

Gimpy CAPTCHA

Source: http://www.captcha.net

Yahoo!® CAPTCHA (EZ-Gimpy)

visual based captchas5
Visual-based CAPTCHAs

Pessimal Print CAPTCHA

Baffletext CAPTCHA

Source: http://www2.parc.com/istl/projects/captcha/captchas.htm

further information
Further Information
  • The CAPTCHA Project: http://www.captcha.net
  • PARC (Palo Alto Research Center) website about CAPTCHAs: http://www.parc.xerox.com/research/istl/projects/captcha/
  • Greg Mori’s web page about his attack on Gimpy: http://www.cs.berkeley.edu/~mori/gimpy/gimpy.html