CAPTCHA & THE ESP GAME SHAH JAYESH CS575SPRING 2008

OVERVIEW OVERVIEW What is CAPTCHA? Examples. Applications. How to Beat CAPTCHA? 3-D CAPTCHA. The ESP Game. Why it is So popular???? Fact about the ESP Game. Questionnaires ??????????

CAPTCHA CAPTCHA A program that can tell whether its user is a human or a computer.

CAPTCHA CAPTCHA "Completely Automated Public ( ALL CODE AND DATA USED BY A CAPTCHA SHOULD BE PUBLICLY AVAILABLE) Turing Test to tell Computers and Humans Apart", trademarked by Carnegie Mellon University.Carnegie Mellon University

CAPTCHA CAPTCHA A PROGRAM THAT CAN GENERATE AND GRADE TESTS THAT: Most Human can pass. Current Computer Programs cannot Pass.

CAPTCHA CAPTCHA Also Described as a reverse Turing test,reverse Turing test It is administered by a machine and targeted to a human. Contrast to the standard Turing test that is typically administered by a human and targeted to a machineTuring test The Turing test is a proposal for a test of a machine's capability to demonstrate intelligence. machine

HISTORY The potential difficulty of differentiating humans from computers pretending to be humans was addressed at least as early as 1950, when Alan Turing described his now- famous Turing test. Automated tests which distinguish humans from computers for the purpose of controlling access to web services were first discussed in 1996.Alan TuringTuring test Primitive CAPTCHAs seem to have been developed in 1997 at AltaVista by Andrei Broder and his colleagues to prevent bots from adding URLs to their search engine. In order to make the images resistant to OCR (Optical Character Recognition), the team simulated situations that scanner manuals claimed resulted in bad OCR. In 2000, Luis von Ahn and Manuel Blum developed and publicized the notion of a CAPTCHA, which included any program that can distinguish humans from computers. They invented multiple examples of CAPTCHAs, including the first CAPTCHAs to be widely used, which were those adopted by Yahoo!.AltaVistaAndrei BroderbotsURLssearch engine OCRLuis von AhnManuel BlumYahoo! The term "CAPTCHA" was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper (all of Carnegie Mellon University), and John Langford (then of IBM).Luis von AhnManuel BlumCarnegie Mellon UniversityJohn LangfordIBM

EXAMPLE Picks RandomRenders it into a String of Letters.Distorted Image. following finding

……and Generates a TEST Type the Characters that Appear in the Image.

To Stop Spammers. Stopping automated posting to blogs, forums and wikis. blogsforumswikis To Protect systems vulnerable to spam, such as webmail services of Gmail, Hotmail, and Yahoo! Mail. Gmail HotmailYahoo! Mail APPLICATIONS

EXAMPLES OF CAPTCHA

EXAMPLES OF CAPTCHA What are this Images of ????????

EXAMPLES OF CAPTCHA The Images need to be randomly distorted …………..

EXAMPLES OF CAPTCHA What are these Pictures of ????????

SOUND BASED CAPTCHA Humans are better than Computers at understanding of spoken Languages.

Extraction of the image from the web page. Removal of background clutter. Segmentation. Identifying the letter for each region. How to beat CAPTCHA?

Steps 1, 2, and 4 are easy tasks for computers. The only part where humans still outperform computers is segmentation. The segmentation becomes nearly impossible with current software. Hence, an effective CAPTCHA should focus on the segmentation.

THE 3-D CAPTCHA The 3-D CAPTCHA and modern video games use the same basic mechanism to generate unique images.video games A single 3-D CAPTCHA image might contain 26 identifiable features and asking for the identification of 3 of those features will result in (26)*(25)*(24) = 15,600 possible combinations while the requirement to identify 5 features will result in 7,893,600 combinations making a brute force attack impractical.brute force attack

THE 3-D CAPTCHA Designing a computer vision program that can recognize the objects within the 3-D CAPTCHA images is intrinsically difficult.computer vision The instructions that accompany the 3-D CAPTCHA image are bound by language dependency. Any entity deploying the 3-D CAPTCHA will need to select the language to be used for the instructions that will accompany the image.

EXAMPLE OF 3-D CAPTCHA We now have the code: CKT

DIRTY HACKS CAPTCHA sweat shops: SPAM COMPANIES HIRE HUMANS TO SOLVE CAPTCHAS ALL DAY LONG $2.50 PER HOUR FOR EACH HUMAN 720 CAPTCHAS PER HOUR PER HUMAN 1/3 CENT PER ACCOUNT.

The ESP Game

Labeling Images with Words………… Man Horse Ground Belly Still an open problem……

ACCESSIBLITY Less than 10% of the web is accessible to the visually impaired. Reason: Most images don’t have proper Captions.

The ESP Game Two Player online Game. Partners don’t know each other and can’t communicate. Objective of Game: Type the Same Word. The only thing in common is an Image.

PLAYER 1 PLAYER 2 Guessing : Car : Hat : Kid SUCCESS! You Agree on CAR !!!! THE ESP GAME Guessing : Boy : Car

The ESP Game

FACT THE ESP Game is Fun !!!!!!! 4.1 million labels with 23,000 players. There are many people that play over 20 hours a week people playing simultaneously can label all images on Google in 30 days! Individual games in yahoo! And msn average over 5,000 players at a time. Individual games in yahoo! And msn average over 5,000 players at a time.

WHY DO PEOPLE LIKE THE ESP GAME?

The ESP Game gives its players a weird and Beautiful sense of anonymous intimacy. On the other hand, the two of you are bringing your minds together in a way that lovers would envy.

Strangely Addictive. It’s so much fun trying to guess what others think. You have to step outside of yourself to match. It’s fast-paced. Helps me learn English.

THE POWER OF HUMAN CYCLES OPEN PROBLEM CAPTCHA GAME

HAS APPEARED IN OVER 50 NEWSPAPERS AROUND THE WORLD. THE ESP GAME

Name That Image Computers excel at sifting information, but they have trouble distinguishing a picture of a tree from one of a turtle. So researchers at Carnegie Mellon University knew they needed human volunteers to successfully label millions of unmarked images on the Web. Luis von Han, a graduate student in computer science, had the inspired idea of turning the laborious process into a two-player contest called the ESP Game Each time you play, you are randomly paired with another anonymous player. You can't communicate with your partner, although you both see the same image. The goal is to guess the descriptive word your partner is typing for the image. Once you both type the same word, you see a new image. Since October the game has attracted 15,000 registered players, and they have created more than 1.5 million labels (a label is a single descriptive word; most photos require multiple labels). The site draws from a database of 200,000 Web images; another 200,000 are to be added soon. Mr. von Han said that properly labeling Web images would allow for more efficient image searching, improve the screen readers used by the visually impaired and help users block inappropriate images.

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