CAPTCHA is a family of Turing tests to automatically differentiate a human user from a computer. This challenge-response test is thus used in computing to verify that the user is not a robot; this verification generally uses the image or sound analysis capacity of the human being. However, the CAPTCHA
acronym simply stands for Completely Automated Public Turing test to tell Computers and Humans Apart The purpose of the tool, as its name suggests, is to detect the presence of robots by differentiating them from humans. To do this, CAPTCHA offers Internet users small questionnaires in different forms.
What is Captcha for?
A captcha is very often used to detect the presence of a robot or to confirm access to an interactive website. However, it is also very present to secure contact forms or online registration. This therefore ensures that the information comes from humans and not from a computer. To sum up, a captcha serves to differentiate a human from a computer program or robot.
What is special about Captcha?
CAPTCHA designates first of all a dialog box, but also and above all the whole of the image generation and network routing protocol associated with the resolution of the Turing test. CAPTCHAs are thus fully automated, they only require a few seconds of the user's time. As we have seen previously, a Captcha generally makes it possible to block the access of malicious machines to websites or registration forms.
The advantages of Captcha
As we have seen before, a Captcha basically blocks the access of malicious machines to websites or registration forms. However, Captchas have several benefits among which we can cite the fact that Captchas prevent hackers from using robots to send phishing emails. They also make it possible to restrict the creation of several fake accounts for malicious purposes. Thus, preservation against fraud is ensured, as for polls for example, this because they make it possible to ensure that each vote is indeed carried out by a human. From the provider's point of view, this obviously allows a significant reduction in the workload of website administrators. Automating requests therefore also makes it possible to reduce the resources of a server necessary for their processing. However, CAPTCHAs are able to take a holistic look at a user's behavior and even history of interactions with content on the Internet.
Disadvantages of Captcha
Nevertheless, Captchas do not only have advantages, there are also disadvantages. Even if the installation of a Captcha is of course necessary, it still requires some specific attention. Another disadvantage that should not be overlooked is the fact that the action of a Captcha can affect the user experience. An action is thus necessary in order to prove that you are indeed a natural person, however this action can slow down or even hinder access to the website or to a form. The "riddle" action can therefore be repeated many times, and your desire to continue will have been well shaken.
Other alternatives today
If they are more and more present, Captchas
are not the only tool to secure a website or a form. Other methods are also used, for example:
- Black Lists (or blacklists) which list unwanted addresses.
- Honeypots that trap "spamming" machines with powerful bait systems.
- Content filters through keyword analysis, which identify suspicious entries
- Web server filters that through complex analysis identify suspicious interactions based on visible characteristics and even known patterns.
However, these different methods are much more complex to implement. This is what Google understood when it bought the ReCaptcha Company in 2009. It has thus developed several versions of its tool. Another cause of this is the fact that the product is free for quantities of less than 1 million calls per month, which gives you a margin. However, there is a counterpart, the tests of texts or images will allow Google to feed the AI (Artificial Intelligence). You are going to identify a word, this word will be used to digitize books and old press archives. Similarly, the recognition of a pedestrian crossing or a bus recognized by you on an image, will thus enrich the base for future autonomous vehicles.