2 More note on CAPTCHAS
A bypass around CAPTCHAs
A simple way around CAPTCHAs has been discovered by the noble denizens of the internet. The essence of the method is to reshow the CAPTCHA to an unwitting human. In our example there are three participants in this shell game of a hack, the security minded email server, the spammer, and an average internet user. The spammer wants to register an account at nobots.com but Oh No! they have a CAPTCHA, whatever will we do? In a feat of unusual intelligence the spammer comes with this clever idea. banner ads is purchased promising free pornography, electronics, or some other too good to be true offer. Our innocent average Joe clicks on the link and is prompted with a CAPTCHA to claim the offer. Little does he know that he is processing the very same CAPTCHA provided by the email site! He fills out the form, no free TV ever arrives and the spambot registers one more email at nobots.com. Because the whole process can be automated now, and nothing is as reliable as an internet user seeking pornography, it is now possible to break any CAPTCHA that couldbe evaluated by a human.
reCAPTCHA is a program recently created to employ the drudgery of filling out a CAPTCHA towards a useful purpose. Created by Luis von Ahn at Carnegie Mellon University the reCaptcha program utilizes CAPTCHAS to facilitate digital conversion of aging books. Due to limitations in OCR software, scanning equipment, and the nature of older printing, it is quite difficult to reliably convert a physical book to digital text. The reCAPTCHA program shows 2 words to the users. The first word is one the software is already confident of, for the purpose of verifying the humanity of the user. The second word is a new unknown word, and here is where the utility of reCAPTCHA comes into play. After a few uses this new word is reliably known and can be added to the pool of known words. reCAPTCHA is currently helping scan books from the Internet Archive and old editions of the New York Times.