Transcript Captcha
CAPTCHA What humans can do, But computers can not. 27.03.2016 Matthias Neubauer Introduction What does CAPTCHA mean? “Completely Automated Public Turing Test to Tell Computers and Humans Apart“ Founded by Luis von Ahn, Manuel Bluhm, Nick Hopper and John Langford from Carnegie Mellon School of Computer Science What is a Turing Test? 27.03.2016 Matthias Neubauer Turing Test (1) Turing: „One day, computers will be as intelligent as humans“ Created a Test to prove it: 27.03.2016 A Tester (für Turing a person) 2 Contestians (1 Computer, 1 Human) in another room than the tester Tester asks questions in text-form Answers are returned in text-form Matthias Neubauer Turing Test (2) If the Tester isn`t able to tell who`s the Human and who`s the Computer => Then the computer must be as (or even more) intelligent as the human being. CAPTCHA: The Tester doesn`t need to be human if it knows the correct answers 27.03.2016 Matthias Neubauer What is CAPTCHA for? Helps blocking automated creations of email-accounts Blocks Computers to vote automatically in online-polls Blocks Search-Engine-Bots and anything where humans don`t want computers to do something 27.03.2016 Matthias Neubauer Can we know that no computer can pass this test? It`s wrong to believe, no computer will ever pass this tests BUT: 27.03.2016 It`s hard do develop a computer program for modern machines that can pass this tests „Any program that can be used to break a CAPTCHA, can be used to solve an unsolved problem of the Artificial Intelligence“ Matthias Neubauer Hard Problem of the AI? What is a „hard“ problem of the AI? 27.03.2016 A problem, the AI-Community is aware of, but wasn`t able to solve So it is very hard to develop a program for it => If a CAPTCHA-breaking program can be used to solve a hard problem of the AI, it is very hard to break a CAPTCHA Matthias Neubauer Why public? The developers WANT the hackers to break their CAPTCHAs „This is how lazy cryptographers to AI“ The results are good, and some textbased CAPTCHAs are already broken 27.03.2016 Matthias Neubauer What kinds of CAPTCHAS exist? (1) Gimpy – a text-based CAPTCHA 27.03.2016 Matthias Neubauer What kinds of CAPTCHAS exist? (2) Bongo – a shapebased CAPTCHA 27.03.2016 Matthias Neubauer What kinds of CAPTCHAS exist? (3) Pix – a picture-based CAPTCHA Eco – a sound-based CAPTCHA 27.03.2016 Matthias Neubauer „Bad“ Computers use humans! Relink CAPTCHAs to human-users Let humans do the work, and tell them it`s a game! 27.03.2016 Matthias Neubauer Resumee Good to secure from „bad“ programs Although wanted to be broken => Use new / unbroken Captchas Captcha – A wanted race with AISpecialists covered as Hackers 27.03.2016 Matthias Neubauer Last Sentence Who knows, maybe one day WE aren`t allowed anymore to create an E-Mail-Account, because we are not intelligent enough... Thank You for your Interest! 27.03.2016 Matthias Neubauer List of Sources [1] Luis von Ahn, Manuel Bluhm und John Langford. The Captcha Project Homepage: http://www.captcha.net [2] Luis von Ahn, Manuel Bluhm und John Langford. Telling Humans and Computers Apart (Automatically): http://www.cs.cmu.edu/~biglou/captcha.pdf [3] Andrew Hodges. The Alan Turing Internet Scrapbook: http://www.turing.org.uk/turing/scrapbook/test.html [4] Luis von Ahn. The ESP Game: http://www.espgame.org 27.03.2016 Matthias Neubauer