What is "CAPTCHA"?

Courtesy: Google Security 

Have you ever been to a website that asks you to enter some jumbled up letters only to subscribe it. Been there, done that! It's very frustrating to differentiate that '1' from a the letter 'I'. These codes are called CAPTCHA. The word is actually an acronym for: "Completely Automated Public Turing test to tell Computers and Humans Apart." When the Internet is supposed to make our life easier and simpler, why introduce some crazy letters every here and there?

CAPTCHA, as the name suggests, is a security filter to differentiate between computers and humans. It is a challenge-response system to prevent spammers from using forms to insert malicious codes into websites. It is the website equivalent of a junk mail, or as we call them spam.

CAPTCHA is a kind of Turing Test. It is supposed to provide a task that a human can perform but a bot cannot. These range from tests involving images to mp3 recognition to filling alphanumeric information to prove that you are indeed, a human. These are based on the fact that computers or spam bots can read the image or the sound file but they cannot describe the information present there, Similarly, Optical Character Recognition (OCR) gives them the ability to read straight characters but not the squiggly ones. It is done to create a thin line between what we can do and bots cannot.

The bots have become smarter. It is already shown that the bots can pass many of the CAPTCHA tests. CAPTCHA, too has come a long way to being just alphanumeric to now being no CAPTCHA reCAPTCHA or you may have seen "I'm not a robot." CAPTCHA or performing tasks that require describing a certain piece of information which is complex for the bots. The only problem is it has become difficult for us too.



Is it the end of road?

Not exactly. There are a lot of other methods for spam detection like The Honey Pot and Akismet but none have come close to being as ubiquitous as the CAPTCHA and most CAPTCHA solutions don't offer accessibility, which is just awful. Those that do typically do a poor job of it. CAPTCHA needs a serious upgrade. With the advent of machine learning, the spam bots race is not going to cool down anytime soon, so we either need a total revamp or a complete shift.

Next time, you are asked to enter some silly codes on websites, blame it on the spammers. Till then, be smart, be safe.