PiCAPTion: Picture CAPTCHAs for Internet Authentication

Abstract

CAPTCHAs are tests that distinguish humans from software robots in an online environment. The most commonly encountered CAPTCHAs today take the form of a garbled string of words or characters. Unfortunately, existing text based CAPTCHAs suffer from several automated attacks. Thus, with the demonstration that character recognition CAPTCHAs are vulnerable to computer vision based attacks, this paper proposes alternatives to the traditional "Text based CAPTCHAs", in the form of "Image based CAPTCHAS", which require users to identify simple objects in the images presented, the argument is that object recognition is typically considered a more challenging problem than character recognition, due to the limited domain of characters and digits in the English alphabet.