November 2019
Intermediate to advanced
346 pages
9h 36m
English
A CAPTCHA is a system intended to prevent automated access or scraping. It does so by asking questions that are meant to recognize when the user is a human and when the user is a program. You have probably seen countless variations of the following screenshot:

Sometimes, the request is to insert a code, sometimes it is to select some objects, for example, storefronts or traffic lights in a series of images, and sometimes the CAPTCHA is a math question. In this chapter, we are going to break a simple CAPTCHA system, called Really Simple CAPTCHA:
Despite its simplicity, Really Simple CAPTCHA is still widely used. Most importantly, ...