CAPTCHA, reCAPTCHA and Related Things

In today’s digital age, when filling out online forms, you may have come across a challenge to prove you're human. This challenge often comes in the form of distorted characters or image puzzles. This is known as CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart). CAPTCHA plays a crucial role in ensuring the authenticity of users on the web by preventing automated bots from carrying out malicious activities.

How many of you've had to fill out some kind of web form where you have been asked to read a distorted sequence of characters as shown below.

How many of you found it annoying? But how did CAPTCHA evolve? What is reCAPTCHA, and how does it help in digitizing books? Let’s dive into these concepts and more.

What is CAPTCHA?

Luis von Ahn invented the term CAPTCHA. It is a security measure designed to verify that the entity filling out a form is a human, not an automated bot. It typically presents a distorted sequence of characters that a person must read and type in a text box. This technology was created by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford at Carnegie Mellon University to stop bots from abusing websites, such as ticket scalpers using automated programs to buy large numbers of tickets.

While CAPTCHA protects websites from various online threats, it also comes with its downsides. Many users find typing these distorted characters annoying and time-consuming. To know how to generate a CAPTCHA, please refer Program to generate CAPTCHA and verify the user.

Problem with CAPTCHA and the Evolution of reCAPTCHA

This project started with the subsequent realization that it seems that approximately 200 million captchas are typed a day by people around the world. So, here's the thing that whenever you type a captcha, essentially, you waste 10 seconds of some time and if you multiply that by 200 million you get that humanity as an entire is wasting about 500,000 hours a day typing these annoying captchas. Even, we can't get rid of captchas, as the security of the web sort depends on them.

However, the creators of CAPTCHA recognized a potential silver lining: the time spent solving CAPTCHAs could be used for something beneficial. This led to the creation of reCAPTCHA, an improved version of CAPTCHA that not only serves as a security measure but also helps with digital tasks that computers struggle with, like book digitization.

reCAPTCHA(reversed CAPTCHA)

reCAPTCHA is a system that evolved from CAPTCHA with the goal of turning users’ CAPTCHA, solving efforts into a productive task. Instead of just verifying that you are human, reCAPTCHA uses the time you spend solving puzzles to help digitize books.

How does this work? Well, many books, especially older ones, have pages that cannot be properly recognized by OCR (Optical Character Recognition) software due to faded ink, yellowed pages, or poor-quality scans. The computer fails to recognize around 30% of the text. The reCAPTCHA system helps solve this problem by asking users to type out those words that OCR couldn’t decipher.

So, every time you fill out a CAPTCHA, you’re not just verifying your identity, you’re also helping digitize a book!

How reCAPTCHA Helps in Book Digitization

Google, along with other organizations, has been working to digitize books. To do this, they scan books and then apply OCR to extract text. However, OCR struggles with poorly scanned pages. For example, older books or handwritten texts can be difficult to process.

Whenever reCAPTCHA asks you to type a word, it could be one of those hard-to-read words from a book that the OCR couldn’t interpret. With this system in place, hundreds of millions of users are helping digitize books every day, making a huge impact in the process of digitizing around 100 million words per day, which is roughly equivalent to 2.5 million books per year. And this is often all being done one word at a time by just people typing captchas on the web.

Types of CAPTCHA and reCAPTCHA

1. No CAPTCHA reCAPTCHA:

Google rolling out a replacement API that radically simplifies the reCAPTCHA experience. They're calling it the "No CAPTCHA reCAPTCHA". On websites using this new API, a big number of users are going to be ready to securely and simply verify they're human without actually having to unravel a CAPTCHA. Instead, with just one click, they'll confirm they're not a robot. And this is how it looks:

2. SQUIGL-PIX:

To solve this CAPTCHA, a user has got to read and understand an instruction written in natural language. A user has to understand what to trace, then find an object on one of the given pictures and trace it. If he/she traces the right object, we may say that the instructions had been understood properly. And this is how it looks:

3. ESP-PIX:

Instead of typing letters, you can authenticate yourself as a person by recognizing what object is common during a set of images. This was the primary example of a CAPTCHA supported image recognition. And this is how it looks:

Applications of CAPTCHA

CAPTCHA is widely used across the internet for various purposes:

• Preventing Comment Spam in Blogs: CAPTCHA prevents bots from flooding blog posts with spam comments.
• Protecting Email Addresses from Scrapers: CAPTCHA protects email addresses from being harvested by bots.
• Protecting Website Registration: CAPTCHA prevents bots from creating fake accounts on websites.
• Preventing Dictionary Attacks: CAPTCHA is used to prevent dictionary attacks, where bots guess passwords.
• Preventing Worms and Spam: CAPTCHA helps prevent automatic spread of worms or spam on the web.
• Search Engine Bots: CAPTCHA prevents bots from flooding search engines with requests.
• Online Polls: CAPTCHA ensures that polls or surveys are only filled out by humans and not automated bots.

Must Read:

• How does reCAPTCHA works?
• What is CAPTCHA code?
• How to fix reCAPTCHA not working?

Conclusion

In this article, we explored the evolution of CAPTCHA and how its advanced form, reCAPTCHA, is not only a security measure but also helps in the vital task of digitizing books. While CAPTCHA may sometimes feel like an annoyance, it's interesting to know that each time you solve one, you're contributing to a larger cause. Whether it's protecting websites from bots or helping preserve historical texts, CAPTCHA and reCAPTCHA serve an important role on the web.