CAPTCHA: What it is, what it is used for and how it works

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If you've ever tried to register on a website or post a comment on a blog, chances are you've encountered a CAPTCHA. This test is primarily intended to differentiate a human from an automated program and prevent unauthorized access. malicious bots to various online platforms.

Although it may seem annoying, this system is key to ensuring the Internet securityIn this article, we will explore in detail what a CAPTCHA is, how it works, the different types that exist, and their importance in cybersecurity.

What is a CAPTCHA?

The acronym CAPTCHA comes from the English Completely Automated Public Turing test to tell Computers and Humans Apart, which translates as Public and automated Turing test to differentiate computers and humans. It is a system designed to ensure that interaction on the web is carried out by a real person and not by an automated program.

CAPTCHAs were introduced as a solution to prevent automated attacks that could compromise the security of websites. They work by posing a test that is easy to solve for a human but difficult for a bot.

What is a CAPTCHA used for?

CAPTCHA has various applications in the digital environment, its main function being cybersecurity. Its most common uses include:

• Preventing mass creation of fake accounts: Many platforms, such as social networks or emails, use it to prevent bots from generating fraudulent accounts en masse.
• Preventing brute force attacks: Protects account access by making it difficult to test password combinations. Passwords automatically.
• Filter spam: On forums, blogs or contact forms, it helps to block comments and messages generated by bots.
• Ensuring the legitimacy of online voting: Used in polls and other voting to ensure that votes are coming from real people and not bots running multiple answers.

Types of CAPTCHA

As the bots have become more sophisticated, CAPTCHAs have evolved to maintain their effectiveness. There are several types, each with specific characteristics:

1. Text CAPTCHA

One of the most traditional. It consists of an image with alphanumeric characters distorted that the user must identify and type into a text field. It may include variations in upper and lower case, as well as unusual characters to make it difficult for bots to resolve.

2. Image CAPTCHA

Widely used today, it requires the user to select images that meet a certain condition, such as choosing all those that contain traffic lights, vehicles or pedestrian crossings. Its advantage lies in the fact that the pattern recognition remains a challenge for automated algorithms.

3. Audio CAPTCHA

Designed for people with visual disabilities, it offers an alternative in which a series of numbers or letters are reproduced in an audio with background noiseWhile it is an inclusive option, it can sometimes be difficult to understand due to noise interference.

4. Question-based CAPTCHA

This format poses logic questions simple or general knowledge, such as “What color is the sky?” or basic math problems. It is easy for humans to solve, but it can be difficult difficulty to interpret for automated programs.

5. CAPTCHA based on social networks

It consists of requiring the user to log in with an account social media verified instead of filling out a form. This helps confirm identity without the need for additional proof.

6. CAPTCHA with time limit

Measures the time a user takes to complete a form. It is assumed that a real person will take a few seconds, while a bot could complete it quickly. snapshot, which serves as an indicator to deny access.

7. Fun CAPTCHAs

Some recent versions have opted to gamify the verification process. This includes puzzle or interactive challenges, such as placing a piece in the correct position or aligning a picture.

8. Behavioral CAPTCHA

Google's reCAPTCHA is an example of this technology. In its most recent version, it analyzes the way the user interacts with the page, determining whether it is a human without requiring you to take any visible action.

What is reCAPTCHA?

Google developed reCAPTCHA as an evolution of traditional CAPTCHAs. Its main advantage is that reduces friction for users and maintains a high level of security.

reCAPTCHA versions

Currently, there are several versions of reCAPTCHA:

• reCAPTCHA v1: It was based on the transcription of words from scanned books, but was discontinued.
• reCAPTCHA v2: Introduced the “I’m not a robot” checkbox and image tests.
• reCAPTCHA v3: It works in the background analyzing user behavior without the need for visible interaction.

CAPTCHA accessibility issues

Although CAPTCHAs provide security, they can cause access difficulties for certain users, especially people with disabilities visual or auditory. The most common problems include:

• Difficulty interpreting images: Visually impaired users may have trouble distinguishing the characters in a traditional CAPTCHA.
• Challenges with audio CAPTCHAs: Background noise and distortion can make it difficult to interpret, even for people without hearing problems.
• Incompatibility with screen readers: Many CAPTCHAs are not designed to be read by assistive technologies.

To address these problems, solutions are being developed such as Behavior-based CAPTCHAs and options completely invisible to the user.

The CAPTCHA is a fundamental tool in digital security that has evolved over time to deal with cyber threats increasingly sophisticated. Their main objective is to ensure that interactions on the web are carried out by real people, avoiding the action of malicious bots. However, their implementation must be balanced with accessibility so as not to exclude certain users.